FAITH

Extruder plans

2009-10-17T03:30:00.000-07:00

MakerBot are sending me fresh capacitors (labelled, this time, I hope) and those parts that were missing from my PCB kits. These should be coming in the next week.

Meanwhile I've been reading up on the various designs and options for constructing an extruder. Looking at the heater details, I was faced with use of copper or stainless steel for the heater barrel and/or nozzle, separate or combined barrel and nozzle, PTFE to insulate or a heatsink block of metal to dissipate heat, uninsulated or insulated nichrome wire or resistors to provide the heating,....
The drive for the plastic rod was originally intended to be a screw-thread, but has been superceded in most cases by a pinch-wheel. There is also a move away from DC motors to a stepper motor.

I already have my DC motor and its RF noise-suppressor board and its controller board. I am planning to make a pinch-wheel extruder, but I am unsure of the rest of the design features to use.
As ever, I posted on the forum and Chris (Nophead) quickly replied explaining the main reasons for different choices.

Since I don't have machining capability for chunks of aluminium into which to push resistors, my heating element will be Nichrome wire. I shall order the insulated Nichrome from Makerbot, perhaps 2 feet, for $1 + P&P. I shall wrap this in Kapton (polyimide) tape, which I shall order from DealExtreme $2.92 (free shipping worldwide, apparently), following BodgeIt's tip. This one claims to work up to 300 oC, whereas the UK supplies state 260 oC. However, I did find reference to one rated up to 260 which stated it would withstand 300 oC briefly. The difference in price works out at about 50 p, so I'll try the one from the States' site, and see what the packaging says when it arrives. I wonder if the cheapest supplier for the UK hapens to be the same company anyway.... their sites are uncannily similar in many respects.

I shall try using my B&Q welding tip to make a combined nozzle/barrel. According to Nophead's work, the nozzle narrow should be around 2 mm or more in length to prevent the nozzle dribbling much. I would like to have a go at Frank's method (August 29 2009 entry on builders' blog) of using a brass nut to conduct heat away from the upper end to an aluminium heatsink. However, I may struggle to get the top (entry end) of the copper welding tip to be cool enough. The rule of thumb is that the heatsink should be not too hot to touch after a time in operation. From what I have read, with a long warm path for the plastic filament to travel before the zone where it melts, the plastic expands too much, which produces a lot of friction, ultimately making it difficult to drive the filament through the extruder.

I do not have a heatsink. However, I may have some aluminium I could use as a heatsink: the flat of the furniture leg I bought in order to attach a horizontal timber arm onto the MDF "vertical base". This would require the purchase of a second one just for heatsink purposes, but is probably the cheapest way of doing this, as it only cost around £6.
The flat has mass 164 g, and is 8x8x1 cm, ie 64 cm cubed. Density of aluminium is approx 2.5 to 2.9 g/cm cubed, therefore this piece of aluminium should weigh (say) 2.7x64 = 172 g. So at 164 g, it IS probably aluminium.
The surface area of the flat is 16000 mm square, so it should act as a good heatsink.

Further information from Nophead concerned the amount of gearing that would be needed to make my little GM3 motor rotate a pinchwheel slowly enough to provide a sensibly slow feedrate for the plastic filament. I don't think it is insurmountable. But I have been hunting a small gear, a large gear, and a tiny pinchwheel.
I have been doing a lot of maths with the various gear ratios, considering what is available and what I need to achieve.
Although this may not be adjustable in use, I have settled on a worm gear, matching large gear onto which to mount a small gear meshing onto another large gear, which will have the pinchwheel mounted on it. I know it'sa lot of gearing.
I shall have to come up with some way of mounting all of these, and I haven't yet decided on what to use as my pinchwheel.

Until I started looking into this, I had no idea there were different sorts of gears, and so many, all for different purposes: worm, bevel, ratchet, rack, spur, helical, pinion, contrate..... and a sprocket is something different!

My design will be a cobble-together, as is typical of repstraps and it may not work....
but I'll have learnt some more along the way, and I can always change components or features as necessary. If I don't try it, I'll never know....

Three step(per)s forward

2009-09-29T00:57:00.000-07:00

I "fried" the last stepper motor driver board last night, and touched it up in a couple of places and removed solder balls before hand-soldering the rest. I cleaned it and checked it this morning, plugged it in and it all works. Now I have a triplet of boards at last. Yay!

Although I can understand the routing of the circuit on the boards themselves, I still haven't learnt much about the circuit diagrams. I know that the white dots on the board denote the negative ends of the LEDs, because I worked out the negative end of the circuit diagram, and I now know that VC+ is the 12 V supply to the board and that VCC, the voltage common collector, is the adjusted voltage, which is 5 V on this board. I came to realise that the arrow heads on the diagram don't have anything to do with direction of electron flow or what is thought of as current; they just mean this part of the circuit carries on somewhere else! Oh, and I now know the symbols for LEDs, resistors, variable resistors, electrolytic and ordinary capacitors. And that's about it.

But I don't know how to count the pin numbers on the chip, for example. And I am confused by the power LED on this circuit - on my boards it is connected straight from the 5 V leg of the voltage regulator, and yet the diagram places a capacitor before it, either an electrolytic or ceramic, depending on which route you take.

Hmm, that really doesn't look like what's actually in front of me.

........................................unless this (below).......................really means this (below)?
And if so, why wasn't it drawn like that for clarity?

Finally, as promised, a costings update:

Farnell sub-total from separate orders = £54.88

A3982 driver chip, part number 1521717, £4.60 and
chip-leg cutter, part number 7256449, £39.90, combined VAT of £6.68
IDC header, straight, 10-way, £1.61 each (x 2), VAT of £0.48

No P&P.

Running total (excluding set of washers and screws from B&Q) = £487.51

Boarding school, term 3. Muddling through the end of year tests....

2009-09-28T05:23:00.000-07:00

Hoorah! Hooray! Yippee! Wonderful! Marvellous! Brilliant! Fantastic! (Can you tell I'm happy?)

After a whole week of head-scratching, web browsing, and advice from my brother, my partner and Nophead, I have finally FIXED my bad stepper motor driver board. Unfortunately, this was the board with near-perfect soldering, of which I was very proud. Now it looks a mess! Anyway, here is the proof it works:

OK, it's not pretty.

The voltage regulator had been tested whilst still fixed to the board (but only by its ground pad). The regulator was definitely faulty. Unfortunately, once I'd removed that, everything else in the 5V path gave readings of zero ohm when tested on a 20 k ohm setting on the multimeter with the +ve probe on the path and the -ve probe on the ground pin of the Molex-style connector. This meant there was a short to ground somewhere, still.

The first thing I checked was the power-indicating LED, as this was what I had replaced twice, once because the first one was dead (although it turned out that that was incidental to the board not working), and once because I checked it for correct orientation when the board still didn't work. The result was that this part of the circuit certainly didn't look tidy, and was a cause for suspicion. I cleaned it very carefully and checked the gap between it and its protective resistor, but it looked separated. I wondered if I had damaged the pad on the board, but without disconnecting it from the circuit there was no way to check.

Next candidate was the damaged track alongside the regulator's space. I decided to cut the track close by the 5V pin' pad,so I scraped off the protective Araldite I had applied, and scraped back to the copper track. Then I very carefully cut the track, and made sure there was no continuity across the cut. Now, using the diode setting on the multimeter, I could light the power LED, so that side of the circuit was sound.
I cut the track in a similar way towards the rear of the regulator's space. Checking on resistance setting 20 k ohm again, the part of the track alongside the regulator gave reading of 1 against ground, meaning no connection to ground, ie no short there.
O.K., they were my top candidates! And they were fine. And I now had 2 unnecessary cuts in my track!

Oh well, nothing ventured, nothing gained.....
Following the track, it goes from the regulator to the electrolytic capacitor from where it splits, with part then heading to the 100 nF ceramic capacitor and to the second RJ45 socket, and the rest going down a "via" under the electrolytic capacitor and off to various other parts of the board.
In order to test this, I cut the track in a clear section underneath the board. Testing the chip end of the circuit to ground, the meter gave 1.
Ah-ha, now the problem is narrowed down to 2 capacitors, the "via" or the RJ45 socket.

The RJ45 socket seemed unlikely to have a problem, and ditto the large capacitor. Having plenty of spare 100 nF ceramic capacitors, thanks to supplies from Nophead after I cracked (a different) one on this board right at the start, I decided to simply swap it.
Some little desoldering and resoldering later, and voila! we have readings of 1 from everywhere on the 5V path to ground. So the problem WAS the capacitor.

Now my problem was the breaks I'd deliberately put in the track....
First I used the conductive pen to fill in the gap in the track on the underside of the board. It takes 10 minutes to get conductivity through the "ink", and testing afterwards showed I had good conductivity between the copper ends.
Unfortunately, when I tried this on the top of the board, I found that I also had re-shorting to ground! Obviously the cuts on the upper side of the board reached the ground connection in the board. So, using a trusty cocktail stick (which should also be added to the parts requirements!) I could paste Araldite (ditto) into the cuts in the copper track, but while that dried, I used the conductive pen to rejoin the breaks going around the cut section. If the conductive pen only works temporarily, I shall solder wires between the track breaks.

Then I soldered a new voltage regulator in place, with the help of Blu-Tack, again. Unfortunately, I knocked the electrolytic capacitor loose, causing more burning plastic due to access issues with my soldering iron as I fixed it back on. I tested it, and the voltage regulator, and then resoldered the first (removed) RJ45 socket. I tested everything exhaustively.

And now we have Blackpool at Christmas! (For those non-UKers, that means all the lights came on.)

My partner thought the board was a gonner. I thought if it didn't work anyway, there was nothing to lose by trying to resuscitate it, and it was going to take another 3 weeks to order a fresh board from the States anyway. And it works.

(PHEW!)

Switching the lights on

2009-09-26T08:16:00.000-07:00

I swapped back to "playing" with my believed-to-be working stepper motor driver board. Looking back, I found Nophead's comment about connecting the enable pin to 0V in order to get the indicating LEDs working. I established from the instructions that the enable pin was pin 5 on the IDC socket, but I didn't know which was pin 5.

After some internet hunting, I eventually managed to confirm the identification of the pins relative to the ribbon cable wires. I thought. I tried that, and got nothing. Hmmm. After some more hunting, I found that my reference website had been wrong - but they're in good company, as Asus apparently got it wrong in their manuals and on their own website! Luckily, this being a communication type connection rather than power, nothing drastic happened when I'd connected the wrong pin.

Using this website, I got the right diagram.
Wire 1 on the ribbon cable goes to pin 1 on the IDC, which is at the end of the row adjacent to the tab on the male connector, shown here as on the top left of the connector, and pin 5 is marked with a wire.

In order to test the stepper motor driver board's indicating LEDs, the pin on the board's connector corresponding to pin 5 on the ribbon cable is connected to ground.
Here is a photo' showing the connector pins 5 (enable) and 9 (ground) linked with a wire.

After arranging this, I plugged in and switched on power to the working board - sure enough the LEDs lit, but one green on one side and one red on the other. Is this correct? Anyone know which ones are supposed to light up?

Second term at boarding school!

2009-09-25T14:51:00.000-07:00

Just when you think you've got everything settled..........

.....My brother pointed out that just because I wasn't measuring 5V out of the voltage regulator whilst it was connected in circuit on the stepper motor driver board didn't mean it wasn't working; with a short-circuit anywhere in the 5V section of the circuit, the current would flow straight to ground, meaning no voltage to measure. However, there were no obvious shorts, no solder bridging two components and I had previously checked that all the resistors apart from the 0.25 ohm ones were sound. After Nophead's advive on checking low value resistors, I noted that my multimeter read 0.5 ohm when the probes were touched together on the lowest resistance range setting, 200 ohm. The resistors gave a reading of 0.8, meaning they are rated at ~0.3 ohm, which is about right allowing for slight inaccuracy of the meter at such low levels compared with range setting.
In circuit, there was no reliable way of measuring the capacitance of any of the small capacitors, so I was going on guesswork that the problem still lay, in fact, with the regulator.

I desoldered one pin on the regulator, and then the other.
I am getting on fine now using the solder braid with flux drawn onto it from a pen. This helps the solder to reflow. I placed the braid onto the top of the pin, acrosswise if possible, and applied the soldering iron tip on top of the braid for a few seconds. I found it easiest to position the braid and hold it in exactly the right orientation, with no twisting etc, with my hand, but once held in place by the soldering iron, I swapped to holding the braid with tweezers so that I didn't burn my hand when it got hot. Access was awkward, and I decided to desolder one of the RJ45 connectors to reduce the amount of melting and burning plastic where the large screws on the soldering iron shaft would catch! I still caught the edge of the Molex connector from time to time. I cut off the used end of desoldering braid holding the absorbed solder and repeated with clean and freshly-fluxed braid until the regulator's pins looked to be clear of solder. The pins still seemed tacked to the board, possibly with sticky burnt flux, so I cleaned around them and prised them up off the board. The pads below are fine.
Desoldering the through-hole pins of the connector was easier, still, after cutting the end of the braid into a point and using the fine iron tip, pressing the braid slightly down and into the hole as the solder wicked up.

Next I tried to desolder the regulator's large ground pad - that was just too tough! I managed to remove most of the solder, but there was some visible under the centre of the pad, but the gap between the part and the board was too thin (top to bottom) to be able to slide the desoldering braid in, and although I could melt some of it, because of the proximity of other components I couldn't use the big flat soldering iron tip, which would have been ideal to melt the lot all at once and allow the regulator to be released.
Eventually my partner went for the brute force option! and created more damage than was intended! Some of the board's contact pad lifted clean away, but the remainder still has contact to ground, and there is damage to the green coating over the track that leads from the 5V pin adjacent to the side of the regulator. There still seems to be continuity everywhere (there should be), though, so I have Araldited a thin protective layer over the shiny copper that is visible.
We tested the removed regulator - it is most definitely dead! Luckily, the minimum order for these had been 5, when I (thought I) needed 3, so there are a couple of spares after all (which is a relief because this was the part that came from RS, who were absolutely useless, and from whom I have no wish to order again)!

My brother rang just as all this was done, and said that I could test this board before putting another regulator on (just in case there is still a short on the board as well) by connecting the working board to power, and connecting a 5V contact on that board to a 5V contact on this board, and a ground contact on that board to a ground contact on this one. The regulator on the first board should easily be able to handle the current for both boards together. At least the power LED should come on for both boards. And if I do Nophead's thing of getting the other LEDs to work, too, I should get proper indication on both boards as well if this board is working. I need to look that up again, but meanwhile I'm letting the Araldite cure.

Boarding School

2009-09-24T13:19:00.000-07:00

I had advice (again) from Nophead (again) to forego the desoldering braid for removal of the dead chip on the first stepper motor driver board, and to cut the legs off as high, i.e. as close to the chip body, as possible. This I did - with the end legs, anyway, but I couldn't find anything fine enough to fit between and cut the other legs. After considering what was available that would definitely do the job with limited manoeuvre room, I decided to buy a chip-leg-cutter. You never know, I may need it in future.
This did the job well. When I lifted the broken chip off the board, a portion of the green board coating came away with it, exposing the copper underneath. The patch didn't extend to any of the pads. Carefully, I coated this with a thin protective layer of Araldite.
This was ancient - I got it in 1991, when I worked for the company! The lids were pretty stuck on, so that trying to unscrew them from the tubes resulted in highly twisted tubes, but putting some grip onto the lids worked. It is good to have some glue you know is still going to work years after first being opened.

Nophead's advice to brush the cut chip legs away with the soldering iron tip worked a treat. Each leg came away easily, and I wiped it from the iron. I used the flat tip to flatten the remaining solder on each pad, and put a thin line of paste along the row of pads on each side before soldering the new chip in place. The right way round!

I checked for bridges, and there were only bridges across legs that are connected with the trace anyway, so I didn't remove those bridges. I checked that there was continuity where there should be, and a lack of continuity where there should be, comparing with the working board. I checked the resistors, and they were all fine, too.

So I plugged in. Oops, no power LED and a very slight smoky smell. I switched straight off.
I took the power LED off, and checked it. Using my new flux pen to wet the component side of the desoldering braid, I was able to remove the solder quite easily. The LED had been fitted the right way around, and it still worked, so I soldered it back on. Hmm.

Since then, I have spent 2 days checking, rechecking and generally scratching my head. I checked all the vias going from top to bottom and did notice a couple without shiny metal rings like the working board has. At the stage I noticed, I didn't know what "vias" in electronics were!
I inserted the probe from my multimeter into the tops of the holes, and turned it around a few times. A thin green film came off, revealing shiny metal once more. I checked there was continuity between the top and bottom, and made sure there was for all such vias.

I checked the resistance for all the resistors, and they were all as rated. The only ones I couldn't check were the 0.25 ohm ones because my meter only went down as low as 200 ohm on its lowest setting.

At this stage, still scratching my head, I posted for more advice on the forum, specifically if the voltage regulator could be checked, and how.

I talked to my brother, who works in electronics, as he happened to 'phone, and he advised that I should check anywhere that a trace has been placed between the pads for a surface-mount component, because there may be a short here. I knew there were a couple of these on the boards, so I checked these, too. No problems found. He also suggested checking every pin, on the headers having 2 rows, against its neighbours. So I did that. No different from the working board. He also recommended connecting the power supply via a 12V bulb rated for 5 or 6 W to the board. If the board were shorted, the bulb would light more brightly compared with doing the same thing on the working board. I put this off because I couldn't locate a suitable bulb or pair of bulbs.

The advice from Nophead was simply to connect 12V power to the regulator and check that 5V came out.
Referring to this website, the power supplied to a 7805 regulator need only be 7V or more; a-ha, say a 9V battery, then, since I didn't want to connect the whole circuit again.
I roped in assistance, and connected wires to a PP3 battery with the ol' trusty Blu-Tack and held the +ve end against the reglator pin next to the "rrrf" text on the board, with the -ve end against the flat plate of the regulator, whilst my assistant measured the voltage off the pin next to the "make" text against the ground pin on the Molex-style connector. Oh. No voltage output. That would be the problem, then. No wonder the power LED didn't light, as it wasn't getting any power at all, it was all just going straight to ground!
That means the rest of the circuit hasn't been tested under voltage since the chip blew!

So for my next order, a new 7805DT voltage regulator..... And I said I might need the chip-leg cutter again, looks like it was sooner than I expected/hoped!

Nophead also explained that I could check the 0.25 ohm resistors by reading the resistance on the meter with the probes touched together, and subtracting that reading from the one I get on the low-value resistor. I'm going to try that next.

In the last 3 days, I have learnt a huge amount about checking boards.
I shall update the project costs soon.
.

Yes!

2009-09-21T12:38:00.000-07:00

I made up the 3 ribbon cables today for the 3 stepper motor driver boards. As I did so, it occurred to me that the cables connected these boards to the motherboard, and that as the cables had the same connectors on either end, the motherboard must have an IDC header, which is the part I ordered singly, instead of a set of 3.
Sooooooooo, I nicked the header from the motherboard kit in order to make up the second board.

On positioning the parts for the second stepper motor driver board, I was careful to orient the chip correctly!

When I cooked the second board, I did so withOUT the large electrolytic capacitors in place.
I cooked on medium to heat the board up and then as soon as the solder paste started to melt I turned it up to medium high. All told, it took just over 3 minutes. Nothing moved at all. There was distinctly more smell this time - last time was almost smell-free.

On cooling, I checked all the contacts from the chip (which was perfect, with no bridges at all) along the traces as drawn on the board. I removed the solder balls with the back of the knife blade again, and checked the resistance across all of the solder mount resistors from solder to solder. All was well. I had just one capacitor that had made good electrical connection but was not good mechanically, having far too little solder. I put the tiniest bit of paste on that end and used the soldering iron with chisel tip to make it good. I also used paste to solder the electrolytic capacitors in place, carefully positioning C11 as far away from the end of the chip as possible whilst leaving exposed solder at the other end of the capacitor to facilitate soldering.

I then ordered 2 more headers for the next board and the motherboard, and a replacement driver chip from Farnell.

I soldered in the stand-in giant resistors, and the through-hole components (with the nicked IDC header), and inspected and tested everything (that I could follow and understand).

JOY! This time, no drama, and the power LED lit up. Yes!
Now I have to wait for my next Farnell delivery before I can do the third board.

Verdict: death by misadventure

2009-09-21T05:09:00.000-07:00

"He died instantly, they say. No pain. He didn't stand a chance, the poor chip."

It seems the first stepper motor driver board's chip didn't stand a chance (and there may have been nothing wrong with the soldering after all). On inspecting the first board for damage, I noticed the semicircle drawing at one end of the chip's print on the board, and realised this was probably supposed to align with the dimple at one end of the chip. Unfortunately, being a complete electronics novice, and being unaware of the marking/importance, I had the chip the other way around. There had been nothing in the instructions to be careful about the chip's orientation. Guess we are supposed to know that. Well, I do now! (Funny how everything else was specified, though.)

I live and learn.

Rice Krispies

2009-09-20T03:52:00.001-07:00

Apparently, Churchill said, "Success is going from failure to failure without a loss of enthusiasm".
I must be heading for success then!

Firstly, I must thank Nophead for sending me those spare parts - I have practice material! More later.

The instructions for the stepper motor driver board say to plug it in to see if it works, but I didn't have a 12V power supply. Maplin, as usual, didn't have what I wanted, so I ordered from Farnell again and ordered spare surface-mount LEDS, too. I was underwhelmed to find the power supply didn't come with a lead! I dug around in the long-since-abandoned-shelving upstairs, and found the power lead for either my old PC or its CRT monitor. It had a 5 A fuse, so that seemed OK. Plugged it into the power supply - and nothing. Checked all the switches were on and the socket was live, all OK. But no power from the PSU. Wondered about that old lead? Then I remembered somebody telling me something about how ATX power supplies differed from AT power supplies, so some internet hunting later, and I found out how to short out pins in the power header for testing purposes.
Usually the power header is a 20 pin affair, but mine looks bigger. It has a separate 4 pin block slid* onto the end of the larger connector.

Here is a picture, with the power header shorted between pins14 and 17:

Thank goodness for the internet and the wealth of information available on various websites.

This done, I switched back on - and it was a good job I was watching the fan closely, because I watched it disappear as it spun at speed, but I couldn't hear a thing. Wow, I know it is called a "silent" PSU, but I didn't expect that they meant it!

Barney reported a blown chip, with the advice to check continuity on the board before plugging in. My meter has dead batteries....

Now I had a working PSU, I switched off, plugged one of the Molex-type leads into the board until it snapped into place and switched on with my finger over the off switch. Here was the crackle and pop. I switched off very quickly with a slight burning smell developing. What was that, you said, Barney? Something about checking continuity everywhere?

Ooops, I have given the chip a contour! but it doesn't look like the board is damaged.

This time following Barney's advice (!) I shall nip the legs with the tin-snips if I can to remove the dead chip. And I'm going to Screwfix now for some replacement meter batteries - open on a Sunday and ~£2 cheaper in total than Halfords.
Then I shall inspect the rest of the board, and CHECK CONTINUITY everywhere. Without the chip in place, I should get better access. Then, if all is well, I shall replace the chip and check the continuity from its legs, too.

Soldering/desoldering learning.
Following on from a link off the forum for Kapton tape supplied by DealExtreme in the States, and looking to see what else they had, I noted that they had desolder braid with lots of reviews, including one that said this particular desolder braid had flux in it, so you don't need to add any. Ah-ha, maybe that's why my desolder braid isn't very successful for me, as perhaps it doesn't contain flux, and I wasn't adding any.
Order from CPC (another part of the Farnell empire) a flux pen. Also a conductive pen as a temporary fix in case I blow any of my board tracks.
I shall try the fluxing/desolder braid to remove the remnants of the old chip legs. If I'm not getting anywhere I shall leave them in place rather than risk damaging the board. Then I'll clean the area with surgical spirit, in case there is contamination after the smokey smell.

Also, I have seen a video of soldering 1206 parts by hand with solder wire, and this requires flux to be put down first and touched with the soldering iron to "tack" the part in place, before laying solder wire partly along the end contact of a component, and just bringing the soldering iron (using a chisel tip, with the flat face downwards) down onto the edge of the pad, sliding it in to touch the part and sliding straight back away. This gives minimum iron-exposure to the 1206 component. I'm going to practise this technique when I have my flux pen. I suspect my 0.7 mm solder wire may be too thick, though; it needs more like 0.4 mm.

I have already practised using the chisel tip and soldering a 1206 component using the solder paste, which itself tacks the part down. This was pretty successful, too. Knowing I can use the soldering iron with the solder paste, when I replace my chip, I'm going to use the solder paste in a thin line across all the pads.

Farnell sub-total = £19.64 (agh, I forgot to order the headers!)

350 W PSU, part number 1277264, £15.68
green LEDs, 1206, part number 122672, £0.061 each (x10)
red LEDs, 1206, part number 1318261, £0.079 each (x10)

No delivery charge, but total VAT of £2.56.

CPC sub-total = £25.14

no-clean flux pen, part number SA00859, £5.79
conductive pen, micro-tip, part number SA00462, £19.35

No delivery charge.

ScrewFix sub-total = £3.82

LR44 cells, pack of 2, part number 44122, £1.91 (x2)

Running total (excluding set of washers and screws from B&Q) = £432.63

So I STILL need 2 headers and another A3982 chip.

* On a complete and utter off-topic aside, I was thinking about how the past participle of the verb "to slide" is slid. That's (about?) the only one. For glide it is glided, pride it is prided, side it is sided, and for ride it is ridden.
Isn't English a wonderful and contrary language?!

Step(per) 1 finished!

2009-09-15T08:13:00.000-07:00

I finished the first stepper motor driver board today. My second mega-resistor went better than the first. I am amazed how often I end up needing to use Blu-Tack to hold things in place; it should be named on the parts list under tools!

So here is the front of the board:

and here is the back, with its near-perfect soldering:

I just wish I could test it, but I don't yet have a 12V power supply, nor do I think I can mock one up, as I did for the 5V previously.

I am very grateful to Nophead who has promised me a replacement 100 nF ceramic capacitor and surface-mount green LED, so I should be able to do the reflow work on the other 2 of these boards towards the end of this week.

I'm hoping to read Barney's blogging of his reflow experiences before I do more, to see if I can pick up any tips.

I really appreciate the help and encouragement and practical assistance given freely on the forum and in people's blogs and comments. It's something special.

I have learnt that these boards that have been giving me quite a challenge are now available ready-assembled! Oh no, they're not are they? I could have waited for that had I known it was in the offing.

Oh well, at least at the end, I can say "I made all of that", with some pride (especially if I have a working 3D printer!) because I knew how to do NONE of this 6 months ago! And I couldn't have done it without the RepRap "community" being what it is.

Meanwhile, I can tackle the cabling, or I've still to try out those penny washers on my mechanical build.

So far so good

2009-09-14T03:03:00.000-07:00

I was soldering the remaining components on the dreaded stepper motor driver board last night.
I started with the small components, my fine soldering iron tip and solder wire. Having clipped one of the RJ45 sockets into the board, I discovered that it was impossible to get the other one in due to the ridges on the sides of the components. I carefully unclipped the first, and filed off the ridges on the sides of both RJ45 sockets that will be next to each other on the board.

I did some excellent soldering of the small-leaded components, and I was so impressed I took a photo'....
This is only the fifth time I've soldered. Can I just say woo-hoo!!!! Yeah!

I found that if the solder wire wouldn't melt after more than 4 seconds, cleaning the soldering iron and/or re-tinning and cleaning it improved the heat conduction. I also noted that just 4 dabs of the 0.7 mm solder wire per lead was perfect for these fine leads.

For the break-off 4 way header, I "Blu-Tak"ed the front onto the edge of the board to make a firm fit ready for soldering. I was glad I'd re-mounted the edge electrolytic capacitor because I wouldn't have been able to fit the Molex-style connector otherwise.
For this and the other large-lead components, I swapped to a larger soldering iron tip.
I used 8 dabs of solder wire for each of these larger leads but on inspection I found this left the solder only level with the board rather than beaded, so I went round and did the same again to get a bead! You really need thicker solder wire for such components.

Here is the finished through-hole soldering. You can see the Blu-Tak still attached on the left of the picture.

For the first mega-resistor, I tinned the leads, which had been bent round very carefully to align with the pads without touching any neighbouring components, nor to have the resistor body touching anything. I also tinned the pads, and then used the soldering iron at an angle that prevented contact with the chip/neighbouring capacitors etc to melt it all together using a little more solder to get a firm footing.
This was extremely awkward and took me a long time. I stopped after the first one, so I still have the other to go. I am not looking forward to having to do this on the other 2 boards. Don't buy these resistors!

It was too late to blog afterwards, but I'm afraid that's when I took the photo's, so they're not so good - but my soldering was fantastic!
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And one was where 3 should be...

2009-09-12T12:43:00.000-07:00

I have set out the remaining components for the first stepper motor driver board. You can see the re-positioned edge electrolytic capacitor.

The two enormous (in comparison) black components on the right are the stand-in resistors, with their leads bent to fit the board's contact pads!
The component in the middle of these two is the high power header connector - you may remember that's the part I ordered in numbers way over the top, because actually you only needed one, which is broken into 4-way parts. The first go caused a 5-way part (!), so after that I tried needle-nose pliers (too wide), and then cutting the plastic with tin-snips. This worked a treat, but I was glad I was wearing eye protection because each cut part fired off, and bounced off 2 or 3 obstacles before disappearing! I would see where it went first and second and then lose it! Took me a while to find it, based on the landing noise it had made!

See the blue header at the bottom? That's the only one I have. Remember there are 3 stepper motors, and therefore 3 driver boards? Somehow I failed to order 3 of these headers!

So for future orders, so far, the list goes:

2 more headers, part 110-3949 from Farnell

1 more ceramic capacitor, 100 nF, part 165-0887 from Farnell

and 1 green 1206 2 mm LED, which I might get from Farnell as well, say part number 1226372 at 6p.

I'm not ordering yet - let's see how many other parts need replacing.
So it will be a while before I finish these three stepper motor driver boards.

Fix part 2

2009-09-12T10:05:00.000-07:00

I cleaned off what I could of the solder on the removed electrolytic capacitor, and manually soldered it back on to the board, using Blu-Tak to steady the side as I did so.
I de-soldered the dud LED, and checked it afterwards - it really is dud. I checked a new one, which lit, and soldered it into place, again using a tiny bit of Blu-Tak against its side. Now it doesn't light. Hmmm - methinks my logic is off, possibly because of the rest of the circuit. I just can't believe this LED is as dead as the other after simply soldering it on. Unfortunately I don't have a 12V supply with which I can check this part of the board, which is the power circuit.

Checking

2009-09-12T06:44:00.000-07:00

Since I couldn't see one of the pads under the edge electrolytic capacitor (C10), I wasn't able to check continuity across the pads to see if the capacitor had made decent contact with the board. I tried checking from the wide terminal of IC3 5V regulator to one side of the capacitor (continuity found with R set to 2000 k ohm on multimeter), but could get nothing from IC3 to the other side of the capacitor.
I decided to see how firmly it was attached, and when it wobbled slightly under pressure, I peeled it away from the board. I shall remove the solder that's there and re-solder by hand.

As for the other electrolytic capacitor (C11), I can't get any readings at all, owing to the proximity of the chip on one side and the molten black plastic in the way on the other.

I checked the LEDs with the diode setting on the multimeter, and was pleased that all A B C and D LEDs lit up, and that using the probe terminals the wrong way round lit up the neighbouring LED instead! That shows that there is continuity of those circuit portions.

Unfortunately, I couldn't get the power LED to light at all, even using the component casing (either way round), so I guess that's a dud, then. That means I can't check the power circuit, with those electrolytic capacitors, as a whole. More hand-soldering coming up, but again, I don't have any spares.

Getting a quick fix

2009-09-12T03:22:00.001-07:00

OK, that wasn't too bad. After perusing various websites to learn how best to deal with my little cooking problems from last night, I set up my soldering iron with its finest tip, and had my solder wire and desoldering braid (and tweezers this time, after discovering I was burning my hand last time I used the braid) to hand. My iron tip is actually finer at the very end than the tweezers.

I started off trying to use the braid to deal with those solder bridges on the chip, but just couldn't get the braid hot enough to melt and draw out the solder in the gaps between the legs. After trying several times, I simply used the iron tip to heat the bridging solder directly, then quickly drew the tip down, bringing the solder with it. This spread the solder onto the legs either side, and I did this for all the bridged legs until I soon had no more bridging.

Here is a picture of the legs on one side of the chip:

and here is the other side:

OK, it's not exactly pretty, but it should work.

Next I used the iron to melt the solder at one end of the cracked capacitor, and used tweezers at the same time to encourage separation. I only moved it a bit whilst the solder was molten. I repeated this at the other end, and went back and forth a couple of times until the capacitor was freed.
While there was free access, I used my Stanley knife blade on its non-blade edge to remove the problematic solder balls, and cleared the others off the board, too.

I put a new capacitor in place, and using my fine soldering iron tip, still, with 0.7 mm solder wire, I was able to solder it in place, although positioning it whilst soldering was awkward. I used a tiny blob of Blu-Tak on the end of the tweezers to try to stop it sliding around. You can see it here (it is capacitor C1 just in front of the chip) and isn't straight, but it has made contact. There is too much solder there, too. Tough!

I used the soldering iron to try to melt the solder under the centre electrolytic capacitor, trying hard not to put too much heat onto the neighbouring (and very close) chip, but mostly melted the black plastic base of the capacitor, so I can't see if the solder has melted!

So here is the fixed? board:

Only, I think there is another problem - the electrolytic capacitor on the edge. The capacitor isn't aligned with its board-diagram. There is contact on one side:

but on the other the lead on the capacitor is visible, but the pad isn't, and I don't know if contact has been made. You can just see the lead obscuring the C6 marking:

Now how do I check the electrolytic capacitors for contact?

....Cook!

2009-09-11T12:33:00.000-07:00

Into the cold frying pan, onto the gas hob turned to medium low. I timed it, too. At 2 mins I could see the first two corner parts (motor LED and resistor R7) going melty, but it was nearly all melty by the time I'd taken the photograph:

It is hard to take photographs above a hot frying pan, so once again, apologies for the blurs!
And you really can hear some little "pop"s.

At about 8 minutes everything was melty, to varying degrees, and those first 2 parts were shiny, so I shifted the board around to even out the heat-load better. You can see them at the top of this picture:

The shiny isn't silver as the solder wire goes, but is gold-coloured.

By 10 minutes, the only parts not shiny were the chip and its neighbouring electrolytic capacitor. I moved the board to centre these over the heatsource, and waited some more.

I was concerned that the chip wasn't properly down, so I...

don't try this.....

tried to press it down with my tweezers..... and nudged it out of place.... at just the wrong time....

:-(

Ooops. Quickly shoving it back where it should be, I waited another 2 mins, and its solder paste did go shiny. One side is well-aligned and the other? Not so great. It's on the pads, but not perfectly.

And I caused a lot of bridging where the solder isn't separated between the legs. I thought it all looked done, so I turned off the gas, and inspected the board from above.

On cooling, I took some more pictures, showing the poor chip legs (the 5 left-most legs are bridged and two to the right are bridged), and solder balls in various places. You can see one here in front of C6, in front of the rear electrolytic capacitor:

As warned in the assembly instructions, I have the centre electrolytic capacitor (on the left in the picture below) not at all shiny, and needing some post-cooking fine-tipped soldering iron attention.

Once cool (about 10 mins), I went around the board and chipped off the solder balls with the tweezers and.....

.....don't do this either.....

where there were 2 between C1 and C4, I think I managed to crack one of the ceramic capacitors. Oh Blogger!!

¦-[

Next time, I need to leave individual components well alone whilst cooking, and have a finer implement on hand for removing solder balls. Perhaps my Stanley knife blade, used on the non-blade side, may be better at removing problems between components if I carefully draw it through the gap.

Oh dear, that wasn't very successful all in all. Will I have to replace the cracked capacitor at C1? It is a 100 nF one, and I don't have any spares.
I have to use the soldering iron to fix the electrolytic capacitor, somehow fix the solder bridges on the chip legs, solder in the resistors that are standing in (literally) for the ones I couldn't find as surface-mount, solder the other through-hole components, and I still have a solder ball between C1 and C4.....
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Ready, steady,.....

2009-09-11T07:48:00.000-07:00

I took the solder paste out of the fridge some hours ago. I had to use pliers to unscrew the clear sealing cap, and to screw on the blue plastic nozzle. Looking at it, I can see patches of yellow in the paste (flux?) as if it isn't properly mixed. You can see it in the picture below under the word "Omni".

The part near the nozzle looks homogenous, though, so I'm not too worried. I probably won't get to the separated paste further down the syringe.

I began to coat the surface-mounting pads on the stepper driver board, carefully doing the pads in the order as given for placing the components so that I wouldn't end up coating the pads for my non-surface-mounted 0.25 ohm resistors. Here is an action shot of paste just about to be applied to the motor pads.

Here is the pasted board - you can see R3 and R16 (below and above the chip location, respectively) left untouched.

Reading those instructions on LED orientation didn't help, because my LEDs have a green "T" marking on the underside, so it wasn't obvious which end is which. I guess if I get it wrong the LED simply won't light!
I went back to RapidOnline, who supplied the LEDs, and looked at the full tech.spec. as given for the part number. The data sheet shows current flow to be in the direction of the "T" from top to stem, so I've aligned the triangle on the LED's data sheet diagram with that on the circuit diagram for the board.

Here is the pasted/assembled board, all ready for frying (except it's tea-time, the cooker is in use, and I'll have to wait!):

I was surprised to find that the board was more robust in this state than I expected, and had no problems moving it to take the photograph.

On the surface

2009-09-11T06:44:00.000-07:00

It has taken me about an hour to get together all the surface-mount parts for the first stepper motor driver board, and I haven't even put them (nor even the solder paste) onto the board yet. I'm very glad I used my own identifiers when I submitted my order to Farnell, because one rating of ceramic capacitor has no useful information other than "capacitor" on the Farnell label, so I was glad of being able to cross-reference. Also, having a spreadsheet of suppliers for each component per board was useful, so that I knew I was looking for a RS part for this and a RapidOnline part for that, for example.

Here is a picture of different packaging, of resistors: same idea but this time mostly soft card with transparent film windows in it.
Here are all the surface-mount parts laid out around the board. You can see one capacitor still in its packaging towards the bottom of the picture - that is to distinguish it from the others.

I had forgotten that I hadn't been able to find everything as surface mount, and now I look at the 0.25 ohm resistor, and go, "Oh my, how on earth am I going to mount this on the surface? It's (relatively) huge".
Now I do remember BodgeIt giving a link to his non-surface-mounted component done as surface-mounted, so I'm hunting that down. I shall have to stand this resistor vertically because it won't fit in any other way. So I'll do that when I do the manual soldering for the through-hole components.

Seeing more clearly

2009-09-11T03:47:00.000-07:00

I had bought a set of magnifying glasses to help with the assembly/checking of the circuit boards. It suddenly occurred to me yesterday evening that I could perhaps try taking the photographs with the magnifying glass, since my camera really doesn't like very close-up work, despite having a close-up setting.

Tried it out this morning. Holding both items steady with the magnifying glass against the zoomed out camera lens, and trying to avoid casting one huge shadow over the subject was tricky, and I had to use Blu-Tak to hold the subject, but I am quite pleased with the results. I shall use this technique in future.
So here is the stepper motor driver board, again,

and then the strip of capacitors showing the opened end if you look really carefully (it is the invisiblest film - do you like the new word?), and then the front of the capacitors' packaging.

You can see the scale of this against the camera strap on the right of the photo'!

First stepper

2009-09-10T13:35:00.000-07:00

I started assembling the components for the first of my stepper motor driver boards today. The one shown on the instructions on the reprap site is red, but mine are all green. The printing on mine is much less clear, too, so I have the website page saved as a file on my laptop, and I am scrutinising the pictures and text on screen rather closely.
Also, none of my boards have been printed or perhaps cut square, so the fixing holes in the corners don't line up.
I shall have to mark each fixing hole individually to mount the boards on Faith.

This is the first board on which I shall be soldering surface mount components. I began with the 0.22 uF ceramic capacitor (as it says in the text), also known as the 220 nF capacitor as it is marked on the board. Apparently. I can't make it out on my own board!

For those of you new to surface mount, this little capacitor (which I am assured is large - ha!) comes in a little strip of packaging. I tried to take a photograph, but the packaging is clear, and the components tiny, and the camera couldn't find it to focus!
You have to peel back the clear plastic film from the back of the packaging to get at the capacitor. And then it jumps right out...
it is a fawn-coloured thing, tiny as I said before (!) and I am wearing grey trousers. It jumped towards me. I had to search for it; I could barely spot it on my lap!

The instructions say to colour it with a red or black pen, to distinguish it from the other similar but differently rated capacitors, but as I had only a green marker pen, mine is green. Colouring it wasn't easy, either!

Here it is. You can just about see it in the photo' (the camera clearly couldn't, or couldn't clearly!)

Oh this is going to be fun, isn't it?!

On a lighter note, I've got my soldering tutorial up on the Builders' Wiki, with a lot of practical technical help from Renoir, and my purple RJ45 cable arrived.
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Camera shenanigans, RJ45s and penny washers

2009-09-07T15:02:00.001-07:00

An aside, really. I have discovered something about my Fuji FinePix camera; when the batteries are getting low (which happens ridiculously quickly), the autofocus doesn't always - it takes about 6 goes to get it to activate even when it is set to come on. That explains a lot of my blurry photographs. Also, I accidentally found a setting to increase the brightness, which makes it much easier to see on the LCD screen whether or not I have a decent photo'.

eBay delight! After yet more advice from the forum folk, I ordered some straight (not crossover) patch (ie not solid cable) RJ45 cables. I have guessed that I will need about 1m lengths for Faith.
Now I could have got these at 99p each, but that would have been boring grey, so I ordered 1 red, 1 yellow and 1 green for £1.25 each from Conquest-Computers, and 1 purple for £1.49 from Bluecharge Direct, all inclusive of P&P.
Because these eBay items are listed separately, the Conquest Computers' order went through as 3 separate transactions. Handily, they worked this out and shipped them all together in a Jiffy-style bag. I am still awaiting the purple one from the other company.
I have also ordered some penny washers from eBay, size M5 with outer diameter 25 mm. I am hoping these will be the right size for the swivel arms of the x/y/z stages.

eBay sub-total = £8.89

RJ45 cables from Conquest Computers, £1.25 each, x3 inc. P&P
RJ45 cable from Bluecharge Direct, £1.49 inc. P&P
M5 x 25 mm penny washers from Astley Components, £3.65 inc. P&P

So recounting costs,
running total (excluding last set of washers and screws from B&Q) = £384.66

The noise suppressor board

2009-09-07T14:25:00.001-07:00

I forgot to mention the problem I had setting up my new soldering iron stand. I had to use the fluted coil (holder) upside down, because my Maplin soldering iron has a couple of screws by the tip, making it too wide to fit in the normal way up. This necessitated using pliers to force the coil apart at the (now) bottom end in order to twist it out, and to shove it over the plastic support!

Today, I set to, soldering the noise suppressor board, and as before got part way through when I had to pause to ask a question of the forum folk; the screw terminals component had leads but also made contact with two other pads, and I wasn't sure if they were to be soldered as well. The advice came that I could ignore them, so I soldered just the leads.
When it came to soldering on the tiny tiny tabs into huge holes on the board, I was at a bit of a loss. I secured the motor against the back of the board using an elastic band (left by the postie). You can see the capacitors' outer legs left un-trimmed, for soldering to the motor casing later on.

The instructions warn you to use a lot of solder, but it was difficult to heat the large round contact and each tiny motor tab (taking care not to damage it) as they didn't fit snugly together. Eventually I had a mass of solder there, but not exactly shiny, no matter what I did.
Soldering the legs of the two outside capacitors onto the motor casing proved to be even harder. I tried cleaning the casing first, and tried to tin the casing before affixing the leads, but neither joint looks pretty, and in fact I had to re-do the second one three times. Then I affixed the cable tie to hold it together firmly, and this second joint clearly moved!
I ended up using the desoldering braid to remove the solder. That wasn't easy, either - I wasn't expecting the braid to get hot, and I found my hand getting uncomfortably hot holding it. Also, it didn't seem to wick, but I did get a blob off at a time. I wonder if that's because of using the higher temperature, unleaded solder?
I tinned the capacitor lead, and squashing the end of the lead down onto the motor with the soldering iron held parallel and on the topp of the lead (and obscuring the lead from view) and moving the iron along and off the tip of the lead as soon as the solder melted. This fourth time made contact.

Not exactly tidy, though!
Still, I set the multimeter to the lowest resistance setting and used it to check from the left screw terminal to the left tab on the motor, and from the right terminal to the right tab on the motor, and both gave 0.05 ohm, so I believe I have continuity despite the problems encountered.

I guess next it will be my first try at reflow soldering....

Soldering - a "how to"

2009-09-07T13:50:00.000-07:00

Here is what I gleaned from extensive reading before I started to solder. I put together everything pertinent that I learnt, in my own words, and went over it afresh before starting on the opto endstop boards. You could call it a tutorial. Unfortunately, it isn't possible to grow a third hand for taking photographs whilst actually soldering, and my photo's aren't perfect anyhow, but they give an idea....

How to....

Check that you have all the right components for the board. It is a good idea to lay them out around the board, each on the respective head/foot/left/right side, to assess sizes and locations of the individual components.

Start with the smallest component on the board.

Firstly, check the component leads for signs of dirt or corrosion (see later), and clean by wiping as necessary. If the component has been shipped stuck onto tape, cut the leads alongside the sticky tape to prevent future issues with glue interfering with the solder joint.

Bend the component leads down to align with the fitting holes in the board. Check which way round the component must be inserted; with some components this doesn't matter, but with others it is critical. Insert the leads, from the top towards the bottom surface of the board, both at the same time, but do not press the component down onto the board, because that may kink and weaken or snap the leads.

For any component that may heat up in use, eg a resistor, leave a small gap so that the component is raised above the board slightly to allow air to circulate and heat to dissipate. For temperature-sensitive components, eg transistors and diodes, where excessive heat from the soldering operation can be harmful, again leave a small gap, so that a small crocodile clip or similar metal item can be attached - during soldering - to act as a heat sink and dissipate excess heat.

Bend the leads outwards away from each other slightly on the underside of the board to hold the component in place. (This picture shows a ferrite bead sat vertically on the board, but most components will be aligned between their fixing holes, known as pads.)

Cut off the leads a few mm (approx 3 mm) away from the board. Do not cut them off flush with the board. Cutting the leads before soldering prevents disturbing or damaging the finished joint.

Repeat with one or two other small components, working from the centre of a big board outwards.

Now heat up the soldering iron. Clean the tip using a dampened card egg-box (my resourceful Dad's method) or a wetted sponge (commercial method). The tip should be shiny.

Apply the tiniest amount of solder, containing flux, to the iron tip, by just touching the solder against the tip, but all around it, to prevent it oxidising. Now wipe the tip on the damp card/sponge.

If the component leads are lightly corroded, and not shiny themselves, use the soldering iron to heat the leads. Without moving the soldering iron, now touch the solder to the lead on the side away from the soldering iron.
Move the solder wire away, remove the soldering iron and check that there is now a layer of solder around the lead. This process is "tinning". "Tinned" parts will solder together well. Discard the excess solder blob on the iron tip by wiping it on the dampened card/sponge. If too much solder is applied to the part being tinned, use desoldering wick/braid to remove the excess by applying the wick to the coating, and the tip of the soldering iron to the wick, gently pulling the wick along under the iron tip as the wick becomes full of solder. Remove both wick and solder together.

On the underside of the board, use the hot iron tip to heat the lead AND the copper connection together, for just a second or two. Now, without moving the iron tip away, add a tiny amount of solder to the side of the lead by touching the solder against the hot lead and copper connection, followed by quickly adding solder, using a dabbing motion, to the side of the lead away from the iron, again down against the copper connection.
Repeat this movement until sufficient solder has been applied to create a good joint. Take the solder wire away, then immediately remove the soldering iron, to avoid boiling off the flux and creating spikes, without knocking the joint. Do not move the board until the solder joint has set.

Now inspect the joint.
The outline of the leads should be jutting out of the solder joint slightly. As the joint cools, it should have concave sides, should be flush against the copper connection, and pulled up around the component lead. The solder should not "bridge" to neighbouring connections. If using leaded solder, the joint should look very shiny; lead-free solder will look a little duller or grainier, but still shiny.
Check the joint from the top side of the board, too; the appearance here should be the same.

If the solder does not look shiny, or has not flowed around the lead well, re-melt it with the soldering iron slightly hotter, and ALWAYS add a small amount of flux, which may be contained in extra fresh solder, as necessary, so that the joint becomes shiny and complete.

Below is a picture of a row of good joints in the foreground, - this was my fourth board ever, so it isn't perfect, but the front left solder-joint is perfect, in size, shape and shininess. The brown marks you can see on some of the others are burnt flux, which can be cleaned off with a commercial cleaner or by scraping gently (eg fingernail), but in this case don't compromise the electrical contact.

Here is a close-up picture of the joint on the left in the background; this isn't good, having too much solder. You can see that the solder is convex instead of concave. However, it has made electrical contact and is a viable join.

Here is a picture showing a bad joint; there are 2 large connecting holes in the middle of the board, and you can see that the top one in the picture has shiny solder in it, whereas the bottom one has dull solder. This would be a bad joint if it all looked like this. In this case, the solder on the other side of the board is shiny and I believe there is a sound connection there. Otherwise this would be a candidate for re-doing the solder joint.

Continue with the other joints, checking each as it is completed, before moving on to the next. Re-clean the soldering iron tip as necessary, probably after every few joins.

When the first batch is soldered successfully, continue with another batch of components, moving up in size and outwards on the board.
Finally, add a tiny amount of fresh solder to the tip, to protect it from oxidation in storage, before switching off. Store the soldering iron covered to keep it clean.
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Testing 1, 2, 3, testing...

2009-09-04T11:16:00.000-07:00

Before I went any further, I wanted to test the opto circuits I'd built, so I needed to know which pins were which on the RJ45 connector. I used this, which was the clearest description I found, with a nice easy diagram - so looking at the RJ45 jack socket on the board, with the board the right way up, the pin on the left is 1.
According to the circuit info. in the assembly instructions, pins 4 and 5 are connected together, and this is where the +ve end of my 5V power supply had to be connected, and pins 7 and 8 are connected together, GRND, and this is where the -ve end had to be connected.

Below is a photograph of my testing set-up, using 3 D cells (giving approx. 4.5V) and some alarm wire all blu-tacked together. It took some fiddling to get continuity; too much blu-tak insulated the alarm wire strands!

I stood the battery-tower up and wedged it inside a perfectly-sized cardboard box to hold it all together better. Here is a photo' of the circuit board with its optical sensor blocked with some folded corrugated card (the wire in the foreground is not actually making contact yet) , and below that a photo' with the LED lit.

Believe me, holding the wires to get this working whilst taking a clear photo' was no mean feat!
Hoorah! All 3 circuits work as hoped, with the LED lighting when the sensor is blocked, and going off when unblocked. I am delighted! My first ever soldering was a success!

Silkscreen and solder

2009-09-01T12:39:00.000-07:00

Some photographs:

here are all the packages required for the opto endstop board laid out,

and here are the individual components placed around the bare board,

and here are the undersides of the three finished items

I know the photo' is poor, what with being blurred and having terrible reflection off the auto-flash, but you can just about see the scorch mark at the resistor on the first one I did (on the left), before I swapped to a finer tip on the soldering iron.

Now I need to determine which connectors are what on the "ethernet" socket and get myself a 5V power source to check all the opto endstop boards.

Here is a better photo' (new batteries in the camera, daylight (of sorts)) showing the first board:

The slight scorch-mark is (on the middle resistor) just above and to the right of the central fixing hole.
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Tuesday trepidation

2009-09-01T04:39:00.000-07:00

I have started assembling and soldering the first opto endstop. These boards are made solely with through-hole components. My first soldering atempt on this PCB left a scorch mark on the board - note Nophead's comment about how the solder pads on the board could do with being bigger.
So I switched off the soldering iron, let it cool and swapped for a finer tip. I'm glad I had bought a set of tip replacements for my iron.

When I got to the LED, I had to ask on the forum what the instructions meant for how to get the orientation correct. The phrase was "Insert the short leg (negative) into the hole closest to the flat side of the silkscreen" - I don't know what that means, nor what a silkscreen is, in this context!
The replies came back that "silkscreen" means the diagram printed on the board (if only they'd written "diagram" instead) so the "flat side" refers to one side of the LED's almost circular diagram, ie the picture isn't completely round - there is a subtle flattening on one side. I'm hoping not all boards are so subtle....

Further information came back that I should not assume that the short lead on the LED is the negative one - it isn't universally true! But that this can be checked by using the lowest resistance range on a multimeter, and touching its black lead against the short LED lead (and the red against the other), causing the LED to light up if the short lead is indeed the negative one.
However, I found this didn't work..... but I found that it did work if I used the triangle (now I know it means a diode) symbol on the multimeter. I only considered trying this setting because I had earlier seen the triangle symbol, labelled LED1, on the circuit diagram for this board.
Looking at information on multimeters, I found that a digital multimeter may not have the right resistance range to check diodes, hence the separate diode-testing setting.
I shall have to try to remember this test before connecting up my other brand LEDs.

My first soldering looked (generally) O.K. on the rear of the board, ie the solder itself looked fairly shiny (I'm using lead-free solder, which doesn't make as shiny a join as the traditional leaded type), concave, although not exactly neat, but it looked dull on the top, and I had used too much solder in places. As far as I can tell, there is, unfortunately, no way of checking the finished board independently of any other boards.

Bank holiday blues

2009-08-31T11:15:00.000-07:00

Well, I never did get started on the soldering. Finally we had a dry morning today, so I sorted out the soldering iron - it went outside for a smoke! It took 5 to 10 mins to clear it.
I tried to fit the first resistor into the opto endstop board, starting with one lead and then trying to manipulate the other lead into the right orientation to insert that one through its hole, too, but found that was nigh on impossible - I was in danger of damaging the lead/s. I've been trying to look up better techniques, which turned out to be a difficult task. There is precious little information out there, as everyone starts from just using the soldering iron! It occurred to me that I can't be the only person who doesn't know how to do this.... I did find some in the end.
I've also been refreshing my soldering knowledge, so I have written my own "how-to", starting from absolute basics for those who are utter novices as I am. I shall amend as I go along, and put the tutorial up on the blog when I'm sure I've got it right.
Maybe I'm actually ready to start now.

...three lights; four lights; five lights......

2009-08-28T07:49:00.000-07:00

(anyone fond of motor racing will know what my heading means) - false start!

My solder, yes SOLDER, arrived in today's post. So, naturally, I thought I'd have a go.
Oh-oh. As soon as it started heating up, my brand spanking new soldering iron smoked rather more than I expected, and as I was planning to practise soldering (why do the American videos all say what sounds like "soddering"?) in the room housing my stick insects, and stick insects being sensitive souls when it comes to aerosols, vapours, and smoke, I have unplugged and opened the window. I shall have to set up elsewhere until the iron no longer smokes so.

Guess what I'll be doing this bank holiday weekend?

Woo-hoo

2009-08-27T03:05:00.001-07:00

The good folks at Farnell, bless their little cotton socks, had refunded £20.75 straight onto my credit card (but fogot to tell me!). They didn't have to do this, as it was my error in the first place, so I am very grateful.
I have now ordered, from Farnell, as it only seems right, some solder wire and solder paste. I'm going for lead-free as an environmental sciency person.

Farnell (second) sub-total £19.26

solder paste, lead-free, no-clean, 5 ml, 10 g, manufacturer: Edsyn, part number 1521898, £16.11
solder wire, lead-free, 0.7 mm, 2 m, manufacturer: Multicore, part number 9887105, 64 p.

When it comes to adding the costs of everything, I can take off £20.75 for the Farnell refund, but add £1.62 it cost me to post the extraneous parts back!

Back on 11th June, the costs had reached £262.88, excluding a set of washers and screws from B&Q, and the welding tips that got missed off, at £2.
Then on the 21st July came the first Farnell order (less the refund now received), £72.08
and the subsequent return postage of £1.62
the RapidOnline order £12.35
the RS order (less the solder paste refund now received), £3.59
the Maplin further order (including 2 LEDs now not needed) £1.99
today's Farnell second order (as above) £19.26

so the running total now stands at a whopping £375.77

I probably wouldn't have started if I'd thought I'd be spending this much, but hey, still having fun, and it's giving me something unusual to talk about at weddings!

No hurry....

2009-08-26T08:06:00.001-07:00

It took a while, but today I received my cheque from RS after the solder paste debacle. I have had no word from Farnell about my refund/credit there (after my over-order error), but I've not checked with my credit card people, and it is possible that my credit card account has been refunded.
I want to start assembling my electronics, but everything is currently on hold.

Patience, I hear you cry!

Joy and distress

2009-08-11T09:34:00.000-07:00

Having been informed by Nophead that I had eleven too many headers (I had ordered 12 24-pin connectors, as listed on the Reprap parts lister, when it seems 4-pins were needed, so one 24-pin cut up into short sections would be enough for all three boards!), I emailed Farnell. I explained that it was entirely my error, that I'd ordered 12 and only wanted 1, and asked if I could send the others back unused for a refund. They emailed to say yes, or at least I'd get a credit raised. Very decent of them, considering!
I've put them back in the post now. That was the joy.

Now for the distress. After RS local trade counter failed to find my goods when I was there, and then took half an hour to determine that the missing item, solder paste, wouldn't be available until the 6th August, I thought I'd better ring the trade counter to check it was there before setting off on my sojourn. I rang the number given for the local counter this morning - but the system automatically puts you through to head-office. I explained what I wanted, and the lady said she'd ring the counter for me to check (since there was nothing on their system) ringing me straight back.

Having heard nothing 3 hours later, I rang again. She said she'd been trying, but nobody answered. She'd continue trying.
Another 2 hours passed, I rang again, and got passed to somebody new, who redirected me to the counter - but all I got was holding messages.
When she went off shift, I got passed to the 3rd operator, who tried again.... Anyway, another 2 hours later, she rang me back to say she hadn't managed to talk to anyone yet (it was now 5 pm) and went away (with me on hold) to consider options.
As a private individual without an account BECAUSE I'D ELECTED TO COLLECT (apparently), she couldn't send me another tube of paste out, because their system didn't have my details on it! It would look like a new order - unpaid. So I'd have to pay again online, and then have a credit put on my account afterwards. Humph. So they'd get to keep the money. Don't like that.
The weird thing is that all my details are on one of their systems - I can get to it all when I log in to their ordering website. After going round the houses, and it being 3 weeks since I expected to have the solder paste, and them not being able to tell me where it was/is, I have requested a refund. I should receive a cheque.
Guess I'll be using my Farnell credit to order solder paste....

The world in a box

2009-07-24T02:59:00.000-07:00

I've been checking all my electronics purchases. The RS parts don't come labelled either - glad I didn't order much from them. The Farnell parts are all labelled with country of origin - this is a real multinational supply. I have parts from China (expected), Taiwan (ditto), France, Ireland, Thailand, Mexico, Japan, the Philippines, Austria, the US, and the ribbon cable seems to be the only part from the UK! Wow.

Do I need a tool for the ribbon cable?

The order of things

2009-07-23T08:33:00.000-07:00

I ordered from Farnell and RapidOnline the day before yesterday. Then I went off to Maplin by bus to get their parts.
Unfortunately, it is apparently Maplin's company policy to stock only 2 of the green LEDs. Be aware of this. It means it's better to buy a bag of 5 from RS instead, if you want more than 2 from a shop. As it is, I ended up taking what they had, and then discovering that fact when I got back home, so then I ordered from RS as well, meaning I'm going to have 7 green LEDs! I was planning to collect the RS parts from their local trade counter today - more later.

Here is a picture of the parcel of electronics components I collected from Maplin.
No I've not a clue what's in it either..... You hand over your list, and receive a bundle from the store room, with no labels. Hmmm. I'm going to have to be very careful collating the different parts for the different boards. And I'm going to have to label the components myself, beforehand, to have any chance of getting the right part in the right place.

The best thing about ordering ONLINE is that you don't have to drag yourself around different shops in order to find exactly what you want/need. Or find that they haven't actually got it. Oh, and you get the delight of (often) finding exactly what you want. Oh, and then you recognise just how far online purchasing has come in the last couple of years. Then you get the joy of the anticipation. Then more joy with the delivery. Then you get to unwrap your "pressie/s"!

And wonder, what on earth is it?

At least online stuff that is delivered comes with a despatch note, identifying what is in your parcel.

I'm very impressed with the Farnell and RapidOnline ordering systems. You can copy and paste a list of your parts with optional extra text in the case of Farnell, so I have been able to add my own identifier, as per my components spreadsheet.
My Farnell delivery arrived yesterday afternoon by UPS in a shoebox-sized carton. Everything is in its own bag, labelled with the part number and a brief shop description. That identifier text I submitted has been added onto Farnell's despatch note, so that I can trace the parts by my own identifier, not just the supplier's. Nice. And my RapidOnline order came by Royal Mail this morning.

I'm not impressed by RS, though. I ordered my 3 different items online, and booked them for collection at the local RS trade counter (TC). I thought that was a fine plan. Turns out that RS TC stands for Really Slow Tree Chopping. I guess.
Anyway, along I went, finding it is at the back of beyond off the bus route, and then a bit further, and then round the corner to the far door, and then a wait. One item appeared. The Chap asked another member of staff. Another wait. A second item appeared from storage elsewhere. Another wait. A third person was roped in at this stage. Another wait. It turned out that my third item, the solder paste, was out of stock. (There seems to be a UK-wide dearth of lead-free solder paste!)
When I'd ordered online, it was all marked "available". Hmmmmph. The Chap then said he'd get my paperwork ready - this was when I think they went out back to chop down the trees! I ended up, EVENTUALLY, with several sheets of paper and an extra one saying that I HAD paid in full. This all took well over half an hour. So I have to go back with that note in 2 weeks' time, 6th August, when they should have the last item in.
Oh the joy of online ordering!!

Every little bit

2009-07-22T10:06:00.000-07:00

I have completed my spreadsheet showing all the parts I need for those printed circuit boards I could not purchase as kits. I have found UK alternatives/alternative suppliers for all parts now, and as cheaply as possible (I believe). The components are for the following Generation 3 boards:

opto endstop v2.1 - need 3

GM3 noise suppressor v1.0 for extruder motor - need 1

temperature sensor v2.0 for thermistor - need 1

stepper motor driver v2.3 - need 3

plus solder paste and tweezers.

I have linked to the spreadsheet below. There are four sheets; the first contains all the parts required, the other three contain shopping lists for the relevant suppliers, including final costs.

Electronic components for Generation 3 RepRap PCBs

Thanks to Nophead

2009-07-22T07:03:00.000-07:00

Yes, that's our very own Manchester-based RepRap Guru, Nophead. (And his wife).
I, rather cheekily, asked if I could go to see Chris' set-up, and HydraRaptor. If you've not read (bits of - it's huge) his blog http://hydraraptor.blogspot.com/, do so now. You'll learn heaps. Anyway, I digress. He offered to show me reflow soldering, as he was about to try it for the first time.

Chris came to pick me up (never let strange people you've ONLY met on the internet have your address without having theirs....well, only if you've got a big weapon to hand - it's OK, I took my crutches!) and I spent a few hours talking with him and his wife, watching and learning, and being supplied with drinks and giant cookies.

Chris was trying out a brand new mini-oven and we had our first experience of reflow soldering.
Reading theory and seeing practice are so different. I saw how difficult it was to get the solder precisely positioned, and got to see how much solder was too much. (I learnt which way was up on various components.) We watched the "cooking" in the oven whilst checking the board's temperature over time. I learnt what the increase in temperature rate should be, approximately, and that there is a maximum of 60s at the top (soldering) temperature, to avoid damaging components. I got a feel for how all this should be. Chris showed me which of the finished joints were bowed the wrong way, which were perfect, which good enough. I know how to poke/scrape the solder balls away - more to the point I know how they look.

Next Chris fired HydraRaptor up - the videos with sound don't do it justice! It's quite loud. He selected a small part and printed it. Again, seeing for myself showed me things I didn't appreciate from the videos, such as the hanging baskets for holding the reels of plastic need to be able to twizzle to prevent the plastic, itself, from twisting as it goes into the extruder. I've seen parts being printed in the vid.s, but I'd never seen one being separated from its raft, before. I asked questions about the choice of raft settings, number of layers, fineness etc. Chris allowed me to keep the part printed, so I have a reminder of how the raft was done.

All in all, I had a fun time, I learnt absolutely heaps, got a feel for what's what, and didn't talk about anything else for the next several hours, including in the pub in the evening! So a big thank you to Chris and his wife for an extraordinary day. Cheers!

Behind the scenes

2009-07-02T05:14:00.000-07:00

Surprise! Re-organising my Royal Mail delivery for the Saturday did work! My order from Makerbot arrived in a box labelled "merchandise", signed (or rather printed as before) Zach. This one is lined with bubble wrap. US postage was paid on 19th May, HMRC added their customs charge label dated 01 June. For those interested, customs charges are due for import into the EU when the value is over £18 for a purchase. The VAT I paid on this parcel was £8.66.
I am amazed by the tiny size of the boards - assembling these is going to be a truly fiddly job.

I have spent a couple of weeks looking at parts, and trying to minimize postage and packing costs to get the electronic components sourced in the UK. Some parts I just could not find, so I had to check what type of size etc they were to find equivalents. Once again, I have been very grateful for all the input from the reprap forum, where several people advised me on UK electronics suppliers and how to select substitutes, and even came up with substitutes for me where I'd drawn a blank.

I've learnt that

P&P can make a significant contribution to costs if you're only purchasing a couple of parts
you can search for manufacturer's component numbers on many sites
some technical customer service help is efficient (see below) - yes, really
on-site searches aren't much cop - sometimes you can get to other options using Google and the supplier's name
the same goes for the forum
sometimes it is cheaper overall to buy 25 of an expensive component, with specifications greater than the original specified part, than 100 of the cheaper part
even online retailers have a few sites where you can pick up parts yourself = no P&P
this is getting even more expensive than I imagined!

I was still looking for solder paste. I have decided to have lead-free (well, I am an environmental scientist, after all). The favoured one, and the one to which I was pointed weeks ago, is still out of stock. There were few options at Farnell, but one didn't have its soldering temperature, not even on the technical details pdf. I went to the manufacturer's website, but still nothing. So I emailed Farnell. Firstly, they acknwledged my email, then emailed to say they didn't know and that they would contact the company. Then they emailed me back with a response the same day! That's what I call good customer service. (Oh, Virgin, Virgin, you've a thing or two to learn!)
I am putting together a spreadsheet of original specifications, replacement part sourced in the UK and its specifications and supplier, and current prices. I need to cycle out to Maplin and RS to pick up a few items, but otherwise all parts are from Farnell or RapidOnline.

I have also taken the top of the B&Q workbench apart, because it really wasn't working - love the height, but... Discovered that the two horizontal arms supporting the wooden tops were not parallel - at all - so the winding/latching mechanisms were strained at silly angles and could not work smoothly. The two aforementioned arms are held by two uprights, which I shall call stilts. The only part orienting the stilts was a bar between them. Unfortunately for me, the bar caused the stilts to be angled in slightly, thereby pushing the upper arms together at one end and apart at the other. The bar turned out to be too short by about a cm. I have removed this bar, and re-assembled without it. Only one clip is being a nuisance now, but that might be because its slide has lost its coating with how it was wedging before.

The other thing I've been investigating (see? Lots going on in the background) is making files for 3D objects. Again, someone on the forum pointed me to software (FREE! or expensive, depending on the version) called David, for turning your 3D objects into scans to build up a 3D image file. Hmmm, interesting. There are a couple of good examples, even with the free version. I have been reading around their forum, too. Seems like another encouraging, friendly, forum with lots of good advice. What, three good fora? Wow!

Wonder if that worked?

2009-06-11T09:00:00.000-07:00

Website forms. Aaaaaarrrrgh!
I went to the Royal Mail site, had to register, and set all the details to pay my fee (apparently only £8 of it is customs fee) - but then there was nowhere to go to request redelivery. So, back to the start and I went through the section for a parcel that couldn't be put through the letterbox and nobody was in. This doesn't have anywhere to explain that the fee is paid, that the receipt number is....

Anyway, I'll wait to see if it is delivered on Saturday as requested.

Preparations for the next stage

2009-06-11T04:37:00.000-07:00

I bought a cheap frying pan yesterday, but haven't decided whether to sacrifice one of our existing ones or use the shiny new one for the "cooking" of the circuit boards on the gas hob. The new one has a bigger base - what is the biggest size board I'll need to make, I wonder?

TK Maxx sub-total £7 on the ticket, reduced at checkout to £6 something just under the 7.

Also, today I got a Royal Mail card through the door: "Unfortunately we can't deliver your item because there's a fee to pay" - ah ha, that'll be the other electronics from the states then!

The payment due is £16.66, which I can either pay online (apparently), but no details are given, or by affixing the right postage to the card and sending it back to them, or in person if I go to collect the item. I guess I'll try option 1, as I can then elect a delivery day to suit.

I must get on and order some components and solder paste now. I've already learnt (thanks Nophead) that my thermistor I bought isn't good enough. Unfortunately, there is precious little information on the RepRap site about specifics required for the components to go on the circuit boards. I expect a few more errors in my orders (if anyone has a parts list for RadioSpares (RS) suitable for any of the 3rd generation boards, I'd be very VERY grateful....).

I've contacted RS, and despite their terms and conditions, and the fact that their registration form requires a company name, individuals are welcome to order from them. Companies get free delivery, but the rest of us have to pay around a fiver, apparently. Or pick up from a local depot within a couple of hours of ordering - I checked the local (Manchester) one, and discovered it is actually in Stockport - which is where I am! That may be useful, if my walking is up to it, as it's a bit of a way off the nearest bus-route.

Time to update the running total costs: the RRRF store order, which was supposted to be 9.70 actually came to £9.69 according to my credit card bill with no extra costs, the Makerbot order came to £58.11, with now an extra £16.66 import tax and fees .

Running total (excluding last set of washers and screws from B&Q in May) = £262.88
(Can I say "ouch" now?)

Exciting stuff

2009-06-02T05:41:00.000-07:00

I've just received my first shipment from the States. This one comes from the RepRapResearchFoundation store. Which reminds me, I forgot to mention that my last little motor was supposed to be "signed for" - but the postie just shoved the Jiffy-type bag through the letterbox. Today's delivery was even more bizarre; I was sat upstairs when I heard the post being delivered. Later on, I went to the fron door to get the post, and planned to take it outside to read over lunch, only there in the open back door way, was more post: envelopes and this parcel.
Today's comes with a customs declaration label stating it to be "sample engineering research materiasl" (sic). The sender's signature is printed. I would have expected that would have to be a signature. Zachary sounds very proper.
Parcelling has been cushioned with, I presume, the US version of Yellow Pages. Good idea. (But a category for "syrups"?) I think this paper tears white, so we can recycle it here.

I ordered 3 opto endstop PCBs, and I seem to have 6. I'll email and see what they say. Not that I mind having 6...

Goods were ordered on 18th May. I had my email notification of despatch on Thursday 28th.
USPS mailing office online postage date is 27th, Royal Mail customs cleared date is 31st, arrived today (2nd June). That's 15 days all told, with no extra customs charges on this one.

This post is going to self-destruct soon....

2009-05-31T12:12:00.000-07:00

Here's absolutely nothing to do with my repstrap. Can you guess what it is?

Yep, I grew a big turd!

(This post will be removed unless I get requests for it to stay...)

Kindness and monkeys

2009-05-29T06:23:00.000-07:00

During the bank holiday weekend just gone, I went to B&Q. Among other things, I wanted to see the welding tips, as mentioned in the forum, as potential extruder nozzles - with 0.6 mm nozzle and a 6mm diameter at the other end. Had to ask where they were. When found, each packet had fewer in than the 5 claimed - and one or more holes in the plastic bags. The staff member (the same guy who had helped with my trolley early on (Mark)) muttered "thieving monkeys" and offered to reduce the price. He put the remaining contents of two bags into one, and priced the 4 welding tips at £2. So I've got four welding tips. I also bought three small G-clamps I'm sure will come in useful in this project somewhere. The purchase went on my partner's card, so I don't have the cost breakdown on me.

Meanwhile, I have received offers of practical help from members of the forum. You know who you are, and thank you. I was quite taken aback, and touched, and didn't know what to say, so much so that those involved contacted me again to check it was OK! It is so good to find a(nother- it's my second) forum where everyone offers encouragement and helps each other without the nastiness so endemic in many fora.
So, if you're thinking of starting a repstrap/reprap, do it, and be assured of positive input. And if someone offers you help, reply straight away!

Today I have opened my email to an email from the RRRF store notifying me of the despatch of my order (from the 18th May) yesterday, the 28th May. So that's 10 days already, before the long-haul delay swimming across the ocean......

Soldering kit

2009-05-23T05:52:00.000-07:00

I bought a 30W electric soldering iron and some associated kit today.

Maplin sub-total = £20.66

30 W electric soldering iron, part number N38AC, £6.99
set of 3 tips, part number N00FB, £4.49
soldering iron stand, part number FR20, £5.99 (meant to get BP57M, £4.99, but couldn't see it)
desoldering braid, 1 mm, 1.5 m length, part number N48FX, £2.29

and my first electronic component:

100 k thermistor, part number CR05F , 90 p!

Running total (excluding last set of washers and screws from B&Q, and the PCBs yet to be finally costed) = £171.42

Motor mounts

2009-05-22T11:46:00.000-07:00

I had previously fixed just the x-motor, but hadn't given a diagram of the positions of its screwholes on its angle piece (motor mount).

I have cut another piece of threaded rod (12 inches) for the z-stage, because I had stolen that one for the y-stage.

Today I drilled all the motor mounts, so here are the position diagrams.

I've not yet finalised the diagram for the z-stage.

Guesswork

2009-05-21T11:22:00.000-07:00

I have cut the upright today, guessing its required dimensions. It is a piece of wood 38 cm tall by 4 by 4.5 cm with a slot cut across the top to accept the furniture leg strut I cut yesterday.

Timber!

2009-05-20T11:19:00.000-07:00

Nothing to do with collapse, yet, but I've prised off the black plastic foot from the furniture leg, measured the inside and I've cut a piece of waste timber to fit. This was stuff stored in the loft from when we domolished a false wall ~8 years ago. I am a little concerned to see a couple of woodworm holes in the timber, although not in the section I've used here. I guess we should check the roof timbers now.

The piece I have cut is 2.2 x 3.5 x 18 cm. I sanded off the splinters, and was delighted to find it fitted first time, slotting straight in with very little play, and I hope the fit is tight enough. I don't know yet if this piece is long enough, so here comes some more development work. Ditto with the height of the upright support timber. I may not know until I have my extruder fitted to my z-stage - it depends on the size of the extruder I use, I think.

Phew!

2009-05-19T14:10:00.000-07:00

Firstly, the extruder motor I ordered yesterday has already arrived! Wow, that was fast.
Also I have now managed to make my Makerbot order - I had tried removing all the security and privacy and pop-up blocker settings, and I'd tried Firefox instead of IE7, but in the end I did all of the above as well as turning off Norton Personal Firewall. That was really a last resort.
I had watched their stock dropping, down to only 2 motherboards left....

Anyway I have ordered:
motherboard 1.1 kit, extruder controller 2.2 kit, three motor drivers (I so want to say 3.3, but actually they're 2.3) as boards only, and a temperature sensor v2 board only.
The Makerbot charge comes to £58.11 inc postage (so far) with current exchange rate.

I have spent much of the day looking at soldering irons and solder paste. There is a lot of choice out there, only I didn't know what features were important. Thanks to some help from the forum, I now have a much better idea. I'll order it as soon as the first electronics turn up.

Oh blogger!

2009-05-18T08:02:00.000-07:00

I have ordered a Solarbotics GM3 motor for the extruder from a UK source: Active Robots! £7.99 inc P&P

Running total = £ 150.76

But I dithered about the electronics too long. Remember my table of what was available? That was only on the 15th (today being the 18th) and now the RRRF has sold out of the Generation 3 motherboard (just the board) and the stepper motor driver boards.
I'm ordering the 3 opto endstop boards and the noise suppressor board for the extruder motor from them NOW.
I'm ordering from Makerbot: 3 stepper motor driver boards, and (gulp) the extruder controller and motherboard as full kits NOW. That definitely gives customs the flag.
This is going to be expensive!
Just checking out now....
....
....
RRRF charge comes to £9.70 inc postage (so far) with current exchange rate.
Makerbot = problem. The checkout procedure won't go beyond selecting a payment method - nothing happens. Oh-oh. I have emailed customer service. I hope these items don't sell out before I can order them or I'm well and truly stuck.

Shuffling on the spot

2009-05-17T10:18:00.000-07:00

You hope you're going to remember everything, but you don't!
I put together the springy/wheely bit of the z-stage, and mounted it on the 'vertical base'. Wondered why it sprung straight off.

Oh yes, I remember now - I need to raise the rails to allow for the long screws on the stage.... I knew this back when I did the y-stage.....

Yet another disassembly, cut the strips, reassemble, realise the rail screws need to be swapped to longer ones as well, re-(re re?) disassemble, reassemble.
I've been cheating and using an electric screwdriver. I've run it flat again.

It occurs to me that a picture of my marking box would be in order, so here it is. I tried to get pictures showing the PTFE disks in various stages of marking up, but the brilliant white sets the brightness settings on the camera all wrong so that the marked lines cannot be seen. Anyone know how to take photographs involving brilliant white without losing dark/fine detail/colours?

The friction seems to be lowest with the most perfect disks on the outside of the rail and the others moving with the springs.

Short back and sides

2009-05-17T06:18:00.000-07:00

Having assembled the z metal framework on the landscape oriented 'vertical base' (v.b.), and realised that its side to side dimension needs to be the same as the portrait oriented z-stage, I have marked out the z-stage with the same hole positions as used for the x-stage (except the pipe clip - I have to see where I can fit that afterwards). This means that I could measure directly off the x-stage to determine how far over the track-rail the stage overhangs, and use this as a guide to mark the cutting line for the left (track-rail) side of the v.b.. Then I've measured 8.5 " (= side to side of the z-stage) from there to mark the cutting line on the other side.
The plan is to cut 3.8 cm off the left and 2.7 cm off the right of the v.b. in effect making my v.b. a square.
In order to line up the edge with that of the stage, if the v.b. is a little too short in the end, I shall place the angles just outside the edge, if a little too long I'll sand a bit off.

More changes

2009-05-16T14:27:00.000-07:00

I have assembled the z-rails on the 'vertical base'.
Remember how I'd decided to turn the 'vertical base' around, to landscape orientation? Well, I drilled my holes like that for affixing the z-framework (mark the holes on the right side through the assembled framework, start drilling from that side but remember to countersink from the other side) and I thought all was well until I realised that the final pivot arms actually go past the edges of the 'vertical base' (v.b.) and the z-stage. They are attached to the final angles, which are attached to the v.b. and extend to the front of the z-stage so it can't fall off the v.b..
So I need to cut the sides off my base now.

Talking about blurry

2009-05-16T10:23:00.000-07:00

I've started to consider the z part now, but, as usual there is something wrong.
In (http://www.reprap.org/bin/view/Main/McWire_Cartesian_Bot_1_2) the BOM for the z part states 24 for the rails (ie 12 inches each). Mine are cut to 13 " each, as per the 'Cut aluminium rails to length' instructions.
The so-called vertical base appears to be the same size as all the stages throughout the webpage.
However, if I put my z rails up and down a portrait oriented vertical base (being 11 " tall as per the 'Acrylic cutouts' section) the size of the aluminium angle means that it doesn't fit over the MDF - it catches the edge, whereas the McWire picture shows a large gap bottom and top. My aluminium angle is 3 cm deep whereas the McWire's is 1.5 ", which is actually larger. So the problem is not due to the size difference of the angle.
Hmmm.
Is the vertical base actually landscape? It really doesn't look like it, even when I zoom right in to the http://www.flickr.com/photos/hoeken/2293533001/sizes/o/ Flickr picture.

I can only assume that the rails need to be longer. But how much longer?
Maths guess: 11 " vertical base + 1.5 " angle + 1.5 " other angle + gap = ~15 "

Now, I've used 94 " of my three lots of 1 metre u-shaped channels (117 ") so there isn't enough left (maximum 13 ") to re-do these lengths. So now what? Does this mean the z-stage doesn't have its full range of movement?

For now I shall have to turn the vertical base around to landscape orientation, stick with 13 " rails, and probably have to cut a new z threaded rod to 12 " because I've nicked its intended one for the y-stage (instead of the 18 " one I'd cut for that).
I may have to buy some new rail and cut a new board (unless the holes aren't in inconvenient positions when turned around) if I need a bigger range of movement. I guess this will have a knock-on effect on the software settings, too.

A flurry of photo's

2009-05-16T04:20:00.001-07:00

I'm too tired to go out looking for tubing, and too tired to work out how to do the z stage/"vertical base", so I've taken Renoir at his word; it doesn't matter what the background is. (Bet you weren't expecting a trampoline, though......)

My photography skills aren't, so apologies there. I don't have steady enough arms for my current digital camera, and often get blurry images, which I didn't with my old film one. (Some of you will have an inkling of why I find this less than easy....and why I'm nervous about the soldering thing, although I do have steady hands...)

I'll get anti-everything for my next camera. Hope the pictures give you a flavour if you haven't already got it. I suspect most of the followers already know what's what.

Here was supposed to be a photo' of my base and one of the x stage only they don't seem to be on the camera - as I say, my photography skills aren't. So here instead we have a blurry close-up picture showing the extra strips of MDF I added to the rails attached to the x-stage to give the y-stage enough clearance:

Here is the y-stage:

(cunningly hiding the error hole)

and here is the top surface of the y-stage (anyone want a spare hole?):

Here is another blurry picture showing how the two washers fail to raise the pivot arm off the stage - I need those penny washers:

Here is a picture of the x-stage assembled on the base:

and here the y-stage covering the x-stage, both assembled on the base:

The base isn't finished yet - it needs its upright at the back to hold the z assembly, and I may need to move the x/y stage assembly backwards on the base. The screws/nuts have not been tightened, since disassembly seems to be a regular feature of my build! The y-motor isn't yet attached to the framework, and the x-motor isn't attached to the threaded rod because I have no suitable tubing. And no, it doesn't look like anything - YET!

Blogging with tables

2009-05-15T13:42:00.000-07:00

I had sudden inspiration about my table problems - look it up on Google!
I was getting a huge gap before scrolling down to see my table on the previous post, and no matter what I tried with the HTML, I couldn't get rid of the gap.
Anyway, thanks to (http://www.bloggertipsandtricks.com/search/label/tables), I've got it fixed now. So thanks to Peter@Enviroman, Nitin, and http://mlawire.blogspot.com/2007/01/table-formatting-in-blogger.html.

I know where to go next time I have problems.

It's all very dark

2009-05-15T11:37:00.000-07:00

I've been trying to take photographs, as I've been hassled about the lack of them, but no go so far. I tried to take some with the camera that is on my laptop, so I could angle it at the subject AND see on the screen what the outcome would be, but the "camera" screen is just black. I've checked through the Readme and all the troubleshooting information, got someone else to go through it, too, but all I can conclude is the camera no longer works. I haven't used the camera since 2005, when it worked fine.

This means I need some help to take the photo's, but my willing helper turned out to be not-so-willing when I asked that the parts be held up against the wall as a blank backdrop!

So for now, sorry folks, I'm stuck.

Ditto with the electronics.

I am looking to get the 3rd generation electronics. The boards + components (in kit form only) are only available in the US and the costs put me above the customs threshold, even if I make the orders from the 2 separate sites. And not everything is available, anyway.

Here is a table of the current state of play:

Part	RRRF org shop		Makerbot
Part	Full kit	Board	Full kit	Board
3rd generation motherboard - v 1.1	--------	$10	$40	-----
stepper motor drivers - v 2.3 (times 3)	--------	$2.50 x 3	$20	$3 x 3
opto endstops - v 2.1 (times 3)	Link says “product not found”	$0.50 x 3	Out of stock	$1 x 3
extruder controller - v 2.2	-------	---------	$30	--------

I am considering having to buy just the boards abroad, and try to get all the components here. Talk about rapid learning as I've never done any electronics like this.

I have been reading the section on "reflow" soldering (http://reprap.org/bin/view/Main/HotplateReflowTechnique), and trying to find a hotplate - we only have a gas cooker/stove (not a good idea!). Argos only has a double one (with several reviews saying it died very quickly), ditto the camping sites. The single ones on Ebay work out around the same price as the Argos double one. I'm still hunting a cheap and reliable version.

Almost right

2009-05-13T10:12:00.000-07:00

"There's a hole in my y-board, dear reader, dear reader,
there's a hole in my y-board, dear reader, a hole."

Now reassembled - but it still doesn't work - the pivoting arm hits the PTFE slider where I've drawn it. Luckily, I haven't got around to glueing it yet.

So here is the amended y-stage diagram:
They need to be right up in the corners (or cut them shorter).

Did you see that?

2009-05-13T09:17:00.000-07:00

Two problems - did you spot one?
The pipe clip should be on the opposite side according to the McWire instructions. I know I've seen it the other way round somewhere - hold on whilst I go looking...

.... yep it's on the Makezine version (http://blog.makezine.com/archive/2007/11/make_a_repstrap_part_2_we_1.html). Y-motor at back. I'm trying to figure out if that matters, having the motor at the back instead of the front.

The other problem is yet another error - I've put one pivot-arm's pivot screwhole in the wrong place. (How did I manage that?!)
I'm getting to be quite a dab hand at disassembly....

On another front, people keep asking me what I'm planning with the electronics to control this thing - well, having seen the Paperduino (http://lab.guilhermemartins.net/?p=817) I'd like to be able to make all the boards in a similar manner. Only I haven't a clue how! The boards required are not available in the UK, so I'm short of options. If I buy from the US, I'll probably get stung for import tax (~15 %) + handling, so I'd rather find a local/European supplier.

The fix

2009-05-12T14:32:00.000-07:00

I've cut four new strips of MDF, and put two under each y-rail. All is re-assembled now.

I have also drilled all the holes in the y-stage, using as maximum the 4 mm drill bit and all the screws are in - all are 5 mm screws. I have drilled out the y-pivot arms, too.

Here is the diagram of the y-stage - the pivot arms are identical to the x- ones

The springs I've used are the 4.0 x 79.4 mm extension springs from the multipack, using 2 together per stage to make up the right length.

Ooooooooooops!

2009-05-12T09:20:00.000-07:00

Well, I said I'd post about errors. I've just come across a teeny weeny little major problem.

Given that I ended up using 3 cm screws for attaching the PTFE disks to the underside of the x-stage, necessitating removal of part of the baseboard to provide enough clearance, that means that my y-stage isn't going to slide over the x-stage. Ooops. Should have thought of this earlier.
Now I know why the other B&Qer used bigger u-channel (ie taller rails).

I have several options:

buy bigger channel (2.5 cm instead of 2 cm) and, basically, start again
use the PTFE sheet (3 mm think) instead of the MDF (6 mm thick) to make the pivot arms
cut my disks smaller (and I only did all the cutting of those yesterday - cutting them thinner will be difficult to say the least)
put a strip of MDF under the y-rails to raise their height (adds 6 mm clearance) - probably the easiest option, although insufficient (use 2 strips??)
all of the above to get enough height?!

I wonder if I'll have to do this for the z-stage as well?

"Ooooow.....

2009-05-12T07:41:00.000-07:00

....ScrewFix"!! (Pardon my French)

I thought I'd struggle up to ScrewFix today to get more washers, and to try out penny washers, now I've found them on their website. Problem was they're not down as 'penny washers' in their catalogue - there are 2 different products labelled 'large flat washers', so I had to guess from the pictures.
And I get home to find I got it wrong! Grrrrr!

Anyway, here are the diagrams I finished yesterday for the x-stage and pivot bars:

The y-stage diagram still needs its PTFE slider positions adding.

Toddling along

2009-05-11T13:42:00.000-07:00

I forgot to say that I have now cut the excess off both sides of my baseboard - I did that last week. I have an amended diagram to reflect the changes. I'll keep on amending it, though, until it is right, as I still have some development work to do with the rear upright post. At that point I shall put the diagram up on the blog.

After a lovely weekend away, I didn't have the oomph to walk up to ScrewFix, so today, in the sun (and wind) I cut all my other PTFE disks from the rod. The picnic table, which is slightly too high for me to get up onto its seats easily, makes a good workbench - it already has gaps ideal for sawing! I cut and marked some more MDF pivot arms, too, for the y- and z-stages.

I then marked the y-stage for the disks/arms. I spent the rest of the time drawing out the diagrams for the x-stage and y-stage hole positions and glue positions. I have nearly finished - just want to check them over before I post them up.

I hope to go out tomorrow, because I can't go much further without more 5 mm washers.

And yes, it's time to do piccies. I need to find a suitable backdrop and/or floor to present clear photo's.

Pet shop blank

2009-05-08T04:40:00.000-07:00

I went to my local pet shop (~200 m away right at the end of my road) today to ask about tubing, but they only do one size, and that looks to be about 3 mm diameter.
Hmm. Trying to think of somewhere else I can try. I only need about 15 cm, if that.

Retailers

2009-05-07T11:02:00.000-07:00

The thing with B&Q, like many other retailers, is that they have now bar-coded every individual item. This means that 1 m long and 2 m long items have their own sticky label bar code. I cannot peel the labels off the channels/angles at all, and although the ones on the threaded rods come off easily enough, they leave their sticky behind. Not what you want for freely-moving nuts on threads.
I tried household soap, then detergent (washing up liquid), then a cleaning gel, and finally a spray containing ammonia, well brushed in with a toothbrush. This finally worked. However, on threading the rod through a nut I found tiny balls of grey glue were forming deep in the thread. I have removed all of these with my fingernail.

I have now attached the motor, using 3 mm screws, 1 cm long, each with 2 washers. The mounting holes are 4.4 cm apart. I used a 5.5 mm drill bit for the motor arm and a 3 mm drill bit for the 3 mm screws. I just need some tubing......

Changes

2009-05-07T07:30:00.000-07:00

Yep, the x threaded rod was too long. I have now cut it back to 51 cm. (And yep I've changed units again!)

I have wrapped my 8 mm nut in electrical tape to seat it firmly in the 15 mm pipe clip, and it took about 15 " of tape to do so - rather more than I expected. I wondered if this had to have some give, or whether gluing it may be a good option?
I have bolted my pipe clip holding the 8 mm nut to my x-stage, and am now ready to sort out the motor.

I still need to cut the extra off the baseboard, but thought I'd do this when I disassemble the x-framework to mount the motor.

Also, I have started a Wiki, which should eventually contain complete instructions, parts, costs, pictures and diagrams. Consider this blog as my lab. notebook, and the Wiki as my SOP/method for someone else to follow step by step.
I'll post links when it's in a fit state to use.

Cheaper

2009-05-06T01:55:00.001-07:00

OK, it's only a small component and a tiny amount of cash, but if anyone wants to do this on an absolutely minimum budget, I have just found:

15 mm chrome-plated Cu pipe clips, pack of 10, part number 17694, £1.53 from ScrewFix,

(instead of what I bought (u-shaped clamps = 15 mm saddle clips, pack of 10, £2.18 from B&Q).

Fiddly bits

2009-05-05T13:20:00.001-07:00

So much for using two washers between MDF surfaces.
Instead, I now have one 8 mm washer (wider) between the stage and the pivot bar, but two 5 mm washers between the MDF and the PTFE, which prevents the disks from rubbing against the MDF where the disk thickness isn't perfectly uniform. In order to fit the extra washer, I have had to swap the disks' screws to the 3 cm length. I now have freely spinning disks, but the pivot bars are not so free. Net result, though, is much less friction.
One advantage of the extra washer is that the disks are now better aligned with the rail when the PTFE slide raises the x-stage slightly above the rails.
Now to sort out some feet for the assembly, once I know how much drop I need for the motor.....

More development....

2009-05-05T08:54:00.000-07:00

...and more errors!
Bending over the tops of the pins holding the springs worked well. The trick was to make the bend-point somewhat higher than the spring. However, I have had to remove one of the washers between MDF layers because two left the pivot arm wobbly from side to side. If only I could find a washer with a 5 mm hole but bigger outer diameter....

Also, on trying out my sliding x-stage, the nuts of the pivot arm holding the PTFE disks hit the base board either side. I shall have to cut away another 2 cm each side. Even then, I shall have to put the whole assembly on feet so that the ends of the screws don't touch the ground.

The locations and the design of the pivot arms works, basically, but there is currently more friction than I would like, and it's not to do with the lack of PTFE slider, unfortunately. I don't know if the friction is too great for the motor or for smooth movement, though, so I shall work on it some more to see if there is something simple I can tweak, but otherwise I shall leave it until it goes motive to find out whether it matters.
On that front, the stepper motors arrived today.

Research

2009-05-04T04:08:00.000-07:00

I have been finding out about washers. I have MDF pivot arms, holding PTFE disks (instead of bearings). To enable my pivot arm to rotate freely, I shall put 2 washers between the MDF surfaces (because both are poor turning surfaces), and one between the MDF and the nut on the arm's pivot and between the MDF and the PTFE disk and between the PTFE disk and the nut.
As an aside, apparently steel makes a good turning surface but aluminium does not.
I shall use 2 nuts together for each of the bolts on the arm's pivot and the PTFE disk.

Development work

2009-05-03T06:36:00.000-07:00

I've drilled all the holes for the frames of the other stages now - only the extruder and bearing arm mounts still to do. When positioning the frame onto a stage, it was easiest to make the frame and then mark through the frame's holes onto the MDF.

I have also started design/development work on the bearing-substitutes and the required positions for the pivot arms with the springs that I have (not 4 ").

I have had a lot of difficulty with the little pins that hold the springs - they twist around in use and the spring slips off. I think it is because the MDF (unlike acrylic) gives a little. I am going to try bending the pin right over to prevent this happening. If my pins are long enough.

I went back to B&Q yesterday - they have lots of countersunk bolts of all different diameters and lengths, in packs of 10 including nuts. These are not labelled/found on the website under countersunk/countersink.
When I have worked out exactly which bits I'm using, I'll put the relevant parts and costings up.

For cutting the PTFE rod, I used masking tape to mark the location of the cuts. This also prevented any skating of the saw from damaging the round surface of the rod, which will be essential to act as low-friction "wheels". In order to drill a central hole, I made a little box of glued-together MDF (the same width as the diameter of the rod and approx the same height as the disks I'm cutting), which enables me to mark the centre of the circle (across the diagonals of the box) very easily, using the disk in one orientation and then in a second orientation 45 degrees from the first. (Perhaps a photo' and/or diagram would help here....)
I used a centre punch, then 1.5, 3.5 and finally 5.5 mm drill bits for my centre hole in the PTFE. The holes were pretty darn close to central. I'm now thinking of marking the centre of the box and drilling a marking hole through that - I may even be able to drill a disk through it if I can find a way of holding the disk so it doesn't just spin with the drill bit....

If at first you don't succeed...

2009-05-01T06:28:00.000-07:00

And if at second you don't succeed either....
OK, if you're trying to put a countersunk 5 mm diameter bolt with a 9 mm diameter head into MDF, use a 4 mm pilot hole and a countersinking marking line of 11 mm diameter.
I've finally got it right now!

(I wonder how many of these sorts of things you are taught/pick up/learn if you get the chance to do woodworking/metalworking at school?)

Motors

2009-04-30T14:45:00.000-07:00

After much discussion on the RepRap forum, I have ordered 3 of the following stepper motors:
NEMA 17 type, part number FL42STH47-1204 from Motion Control Products Ltd, webpage http://www.motioncontrolproducts.co.uk/product_info.php?cPath=4&products_id=47.
Basic details are Voltage: 4V, Current (phase): 1.2A, Inductance (Phase): 6mH, Holding Torque: 45Ncm, and it is a 1.8 degree stepper. Heavy, though at 150 g, but cheap at £9.26 each.
From trials of other motors it seems that the holding torque never gets to the rated values (of ~ 0.3 Nm and upwards) on the motors tried by others because of the current (ie electric current A) limits imposed by the controller electronics.
That's if I understand it....

Motion Control Products sub-total = £45.75 inc P&P

Stepper motor, part number FL42STH47-1204, £9.26, x 3

Running total = £142.77

2009-04-30T12:03:00.000-07:00

I've cut the 3.6 cm edge off the MDF now. I've just tried screwing through the MDF - I need to make the pilot holes 3.5 mm next time, and also make the countersinking err towards larger rather than smaller for a flush finish.

2009-04-30T10:10:00.000-07:00

When marking through holes to locate drilling holes in the y and z angles, make sure you mark the outside, not the inside, or the measurements won't be right! Nearly got that all wrong.

I've been looking at http://www.reprap.org/bin/view/Main/McWire_Cartesian_Bot_1_2 to work out where to attach the y-rails to the x-stage, and two pictures show them in very different places. I have plumped for centring the rail across the stage to see if that works.

Here is a diagram of the y-rails:

I have also chosen where to put the fixed side bearings, or PTFE disks in my case, and will experiment with springs and the swinging brackets. I'll put up the x-stage diagram when it's decided.

Drilling

2009-04-30T06:40:00.000-07:00

I spent yesterday evening and this morning hunting for suitable stepper motors. Unfortunately, the requirements don't seem to have been quoted anywhere. Actually, the fact that you need 3 stepper motors at all has been omitted from the parts list for the McWire on http://parts.reprap.org/part/module/McWire+Cartesian+Bot+v1.2 and for the Seedling on http://parts.reprap.org/part/module/RepStrap+v1.0+%22Seedling%22!

This afternoon I marked all the base drill-hole positions with a centre-punch and hammer and using an electric drill drilled the 3 mm pilot hole in the MDF, then used the countersink bit afterwards. I used a 1.5 mm drill bit, then the 3 mm drill bit and finally the 5.5 mm drill bit to go through the metal pieces for the base. This helped keep my drill-holes centred on my mark and therefore as accurate as I could make them. I filed off the burrs with my hand metal-file.
Before assembly begins, I shall use these pieces (drawing through the holes) to mark the positions of the holes on the rails and angles for the y- and z-stages, because they are to be assembled in the same way.

Marking for drilling - or more sawing....

2009-04-29T11:41:00.001-07:00

Well, I said I wanted to post about errors as well as successes, so here's the first. Having made my MDF base 24 " wide, I realise now that sitting the metalwork on the MDF won't give the x-stage stepper motor any room at all, so I am cutting 3.6 cm off down the left side of the MDF base when looking at its bottom face, which is where I am marking the drill-holes. I may need to move the whole assembly backwards, but time will tell, or I may need to use feet to lift it off the floor, but as I don't know what motors I'll be using yet....

Anyway, I have drawn diagrams of where to site the drill holes:

I shall use the countersink 5 mm screws I bought earlier today. I have measured the top of the screw at 9 mm, so I have also marked a 9 mm line across the marked positions on the MDF so that I can drill a countersinking hole to the right size - drilling from underneath. I shall also drill 3 mm pilot holes right through the MDF and 5.5 mm holes through the metalwork.

The nuts and bolts of it all

2009-04-29T08:13:00.000-07:00

Screwfix and Wickes are decidedly short on choices of bolts. So much for saying I'd go get the screws etc as and when I needed them since Screwfix was only up the road.... I picked what I wanted off the website but when I got to the shop it wasn't in their catalogue so they don't stock it.
So instead of buying a small number (25) of the right size bolts I ended up buying a whole multi-pack of assorted sizes for rather more expense, because that was the only option. And why do bolts come in packs of 10 or 25 whereas the nuts only come in packs of 100?

So I ended up buying the following:
Screwfix sub-total = £24.30

countersinking drill bit, part 11311, £5.37
machine screw pack - for 12 countersunk 5 mm diameter bolts at 2 cm length for fixing rails/angles to MDF - part 13352, £14.99 (ouch)
5 mm nuts, pack of 100, £3.94

Running total = £97.02

Unfortunately, I forgot to get the 8 mm nuts to fit the threaded rods......

BIG CUTS across the board...

2009-04-28T06:54:00.000-07:00

I used my new workbench and jig-saw to cut the MDF - took about an hour. Then I did the threaded rods, cutting through the hardened outer with the saw and then snapping off. The first one was harder, the second cut easier and the third cut middling! Guess the material isn't consistent. That took another hour. Then I cut the U-shaped channels. Although I started with the jig-saw, it was easier, actually, to use my Boa saw (a kind of hacksaw, only better for this kind of thing).

The workbench has well and truly been christened - I used it at three different heights depending on the job in hand, but I took a graze off the top of one handle, off one side of the top and onto the metal top support too! (Design-flaw: these supports need to be lower to avoid the jig-saw blade depth.)

I filed off all the sharp metal ends as I went with a little hand metal file.

Cutting the aluminium angle and filing off any sharp bits took about an hour and a half (again starting with the jig-saw but swapping to the Boa) and cutting the PTFE took under an hour. Don't try cutting this with a jig-saw - just doesn't! I filed all the fluffy cut edges off with the same metal file.

The only thing I've not cut is the PTFE rod. I haven't decided exactly what I'm doing with that yet.

Markings continued (still)

2009-04-27T13:57:00.000-07:00

Today I marked up the aluminium angle,

two pieces at each of the following measurements:

9 "
6 and 3/8 "
9 and 1/16 "
5 and 15/16 "

and one at 2.5 ".

Hmmm - interesting

2009-04-23T12:37:00.000-07:00

Marking onto PTFE turned out to be interesting - pencil didn't work at all, and trying to make small measurements marks with a ball-point pen was a bit hit and miss, but marking lines with the pen was largely fine.

I don't know how long to make these PTFE strips (they're 0.5 " wide), but the instructions (http://www.reprap.org/bin/view/Main/McWire_Cartesian_Bot_1_2) say there are 12 of them, and the total number listed in the BOM is 24...

In the pictures they look about 2.5 " long, judging against the size of the stages.
Meanwhile, the BOM under (http://parts.reprap.org/uniqueparts) states 24 " of PTFE strip - although that may just be the size of the supplier's part.

So, I'm going to go with 2 " per piece of PTFE.

Workbench

2009-04-22T14:18:00.001-07:00

Finally got the workbench finished. Ish. Neither of us could get the spring-pin to hold through the handles despite much hammering, so I'm going to get a narrow and long bolt and nut per handle to secure them.
Seems a bit rocky because the upright height-adj. tubes are too loose in their supports, but otherwise OK. There are more holes for the positioning wedges on the wooden top than on my Black & Decker Workmate, and they have a concave side to clamp things vertically. And the height goes to huge, so that should be very useful!

Confusion

2009-04-22T07:25:00.000-07:00

Hmm - confusion, methinks.

According to http://www.reprap.org/bin/view/Main/McWire_Cartesian_Bot_1_2 the x-thread is 19 ", y 11 " and z 9 ".

Except under the bill of materials (BOM) section, where x is 24 ", y is 18 " and z is 12 ". These measurements are the ones I used to mark my threaded rods. Again, I have chosen the longer lengths because I can cut them down as necessary, but once cut too short you're stuck with it!

Markings continued

2009-04-22T01:21:00.000-07:00

For all those of you who have to cut by hand or using hand-held tools, here is a plan of the markings on the MDF, trying to make best use of material.

The hashed area is not used - yet.

I marked it in pencil, and discovered you can use a rubber (eraser) to rub out on MDF if you're gentle.

For the threaded rods, I marked the lengths using masking tape on the waste side, so that is where I can clamp the rods for sawing.

GO! Tues 21st April

2009-04-21T12:23:00.000-07:00

Well, nearly. I spent all morning building up the workbench, but haven't quite finished it yet. Seems to have a design (or pre-assembly) flaw, and also some holes need drilling to get them to line up.
I have marked up most of the pieces for sawing, though:

u-shaped rails - two lengths at 21 ", four at 13 "
threaded rods - one length at 24 ", one at 12 ", one at 18 "
MDF - four rectangles of 8.5 " x 11 ", one at 24 " x 22 "

The last rectangle is to be the base, with a 24 " front. This is the length of the x-screw thread. The distance front to back allows for the 18 " y-screw thread, with some added clearance in front of and the length of the rear upright added on. This may turn out to be too big, but I can always cut it down, whereas I can't grow it!

I warn you now, this is going to be a nice little mix of metric and imperial - just like the UK!

2009-04-20T10:21:00.000-07:00

OK, that went relatively well - my longest wait was for a member of staff to come to my help, rather than when I ordered the taxi!
The chap who got me a trolley also loaded it from various aisles for me, wheeled it to and through the tills and outside ready for the taxi. I had to laugh because he picked a rubbish trolley with a jammed wheel! A whole wealth of tools and equipment on hand, and no fixing done there!

Itemised shopping list so far, including earlier purchases:

B&Q sub-total = £57.47

u-shaped clamps = 15 mm saddle clips, pack of 10, £2.18 - not on their website, (aka pipe clips) - guessing the size required, but it won't break the bank if I've got it wrong.
threaded rods, 8 mm x 1 m, part no. each £2.02, x2
aluminium angles = raw aluminium corner, 3.5 cm x 3.5 cm x 2 m, part no. 3232630508305, £13.41
aluminium u-shape rails = anodised aluminium U, 2 cm x 2 cm x 1 m, part no. 3232630214756, each £7.94 , x 3
acrylic = OK, it's MDF, 6 mm x 1220 mm x 607 mm, part no. 5022652550011, £5.48
flange = aluminium furniture leg, square profile, part no. 5013144016191, £5.48 (furniture leg)
bolts for flange = machine screws, pack of 10, 5 mm x 5 cm, part no. 5020789853487, £3.06 (aka countersunk bolts and nuts)

Maplin sub-total = £2.99

4 " springs = 150 pc spring set, part no. , £2.99 - a box of extension springs (and others), hoping to be able to select correct sizes as appropriate.

eBay UK sub-total = £12.26

Teflon strips = PTFE sheet, 3 mm thick, 10 cm x 22 cm, £6.28 inc P&P, from seller: gfgplasticfabricationsltd
roller bearings = PTFE rod, 25 mm diam x 22 cm, £5.98 inc P&P from seller: bunaday - this item to be cut into rounds

I also bought a new workbench because our existing one is too short for tallish people like us. I hope it's good enough, it is B&Q own brand, part no. 5050451, £29.98. We needed this anyway, so I'm not including this in costings for the project. I'm also not including (for your purposes) the taxi fare home £5.

Running total = £72.72

Crutches

2009-04-20T04:27:00.000-07:00

Being on crutches, I looked up all my large items online - only to find that none of my suppliers have these parts available to order online. So I rang B&Q to ask if I can get someone to load my trolley for me (too big for me) and to take it to the checkout. I rang my local taxi company to make sure I could get my 4 foot x 2 foot piece of board home, as I don't drive.
Everyone says no problem, so I get to find out later today.

2009-04-19T12:46:00.000-07:00

See? still learning
My details already have the y threaded rod at 18 "....

And my MDF base will need to be thick enough to ensure the overhanging x motor clears the floor, or perhaps I can use little feet to raise the bed off the floor.

Learning

2009-04-19T12:25:00.000-07:00

Things I've learnt so far

Use 15 " y-axis threaded rod instead of 13 ". (Ref: BodgeIt) Not sure why, but happy to go with 15 " - can always shorten it, but couldn't lengthen it!
Use 8 mm threaded rod instead of 6 mm so it won't bend so easily. (Ref: BodgeIt)
Don't buy the screws as listed for the McWire (ref: PeterG) - fair enough, I shall figure out what size/length I need as I go along. (UK seller Screwfix is only a walk up the road.)
Don't buy the springs until you determine what lengths are actually needed given the placement of pre-ordered x, y, z plates (called stages). OK, what I'm planning is getting some springs, and then placing holes appropriately. No holes will be in the same place anyway due to design alterations (eg MDF baseboard, no piping, flange, etc)
Don't expect anything to go smoothly - it won't!

And don't try to get your straightness-checked 1 m lengths of threaded rod in a rucksack on your back onto the bus.

I hope I remember to make all the necessary alterations in sizes of nuts etc to account for all of the above.....chances?

Nope, thought not.

FAITH - the CopyCat Bot

2009-04-19T09:35:00.000-07:00

How It All Started - a brief (ie 4 day) history

Wednesday 15th April 2009
Thinking about buying a plastics printer, and looking again at the RapMan. It doesn’t seem much different from the latest Darwin, and costs are reasonable, but…

Thursday 16th
…..looking at Darwin development, and the RepRap site with its “How to build a ….” reprap or a repstrap……. “I just wonder if….”
I hadn’t heard of the Repstrap, so I followed the link and was fascinated….

Lots of research about what may be doable – well the site does say it should be buildable by someone with "no special knowledge or expertise"…. well, that's me!

Friday 17th
The more I look into it, the more I want to build my own and have opted for the McWire (http://www.reprap.org/bin/view/Main/McWire_Cartesian_Bot_1_2) because it appears to have the most comprehensive pictures/instructions and hints. By Friday evening I’m hooked, and I’ve posted on the RepRap builders’ forum.

Saturday 18th
Research: it wasn’t easy to find the steel plumbing pipe in the UK, so I looked for alternatives.

I stumbled across the Wiki for the Lego reprap and the Fisher Technik one – WOW! I also kept on reading about other’s versions and problems and solutions.

Some people had used solid bases instead of plumbing pipe.
Advantage: no skewing
Disadvantage: lack of clearance below moving parts.
Plan: use a wide u-shaped solid base.

I also read that getting the holes in the right places wasn’t as easy as it should be, given that you can print off diagrams to tape onto parts in order to locate those holes. This was when I decided to use MDF for the x,y,z stages instead of expensive, and breakable acrylic.

Then what to use for the upright? Small sections of timber, propped with triangular support blocks.

Then how to hold up the upright known as “vertical base” without the plumbing pipe and flange? Hmm.

I’m spending a lot of time thinking about the plans, by now, so I added my marker to the RepRap map.

Sunday 18th
After a night of thinking about it, I had an idea of using a furniture leg with its attachment plate instead of the flange.
After a little scouting round B&Q, I found the perfect answer: a square-profile, hollow leg with plate with pre-drilled holes. Not expensive either, and fits smaller screws than the bolts required for the plumbing flange, thereby negating the need for really thick material for the vertical base. At least I think that’s why that sheet is thicker than all of the others. Time will tell when I start to put this thing together.

OK, committed now – having bought (some of) the bits, SHE’S OFF!