Chapter 12 - In which I finish the X axis, and have a good idea

I wasn't happy with how the X carriage was travelling, and so I loosened off the smooth rods and rotated them (one at a time) until the carriage moved much more freely. I then fitted the belt clamps.

As you can see, the suggested M3 by 25mm screws are very long. In fact the back pair are so long they interfere with the smooth rods, and the carriage binds (this is probably due to how the carriage sits on its bushings). I replaced the rear screws with a pair of 12mm ones taken from the X axis ends (which were too long in the X ends anyway, and were replaced with some M3x6 screws I had found in a draw earlier).

I fitted the X belt in the same orientation as the Y, namely with the teeth facing downwards in the clamps. It was only when I threaded the rest of the belt around the idler and back that I noticed that it was wrong - the teeth should face upwards, and the belt travel above the carriage rather than under it. I reassembled it and tightened everything up. The carriage now moves very smoothly, seemingly with no backlash.

I cut the belt off leaving a little for adjustment later if needed.

And that's as far as I can go today. Next I will build the electronics, but I need a PSU before we have any movement. I can also build the extruder once I get a few more bits delivered.

Whilst in the draw that yielded the earlier M3x6 screws, I also found the solution to the spring problem. I had previously been unable to find a cheap source for the springs needed to tension Wade's idler bearing in the extruder. I found this clothes peg, the spring from which is perfect:

I scoured ebay and picked up a pack of 24 for £2.50 - that's just over 10 pence each, a marked improvement on the £1 or £2 each I had previously seen springs going for.

Next up: Electronics build

Chapter 11 - In which more gets built, and I spot another potential problem

Encouraged by the progress made on Thursday, I pushed on on Friday. I started by fitting the belt mounting clamps, and the Y axis belt. This turned out to be pretty tricky, and during the fitting and tightening process I had the printer on my knees and upside down at least twice. Eventually I got everything tight and the belts with (hopefully) the right amount of tension in them.

Next it was time to fit the X axis to the vertical rods. I used the bottom plate to hold it horizontal whilst I manoeuvred the bushings into place. I held them in place with blue-tac while the glue dried.

I left the screws on the X rods loose whilst the bushings were gluing, and tightened them up afterwards. Whilst the glue was drying, I made up the Z leadscrew clamps. These are the alternate clamps supplied by Nophead, and require additional M3x20 bolts, nuts and washers.

I screwed them together taking care to make sure they were the right way round.

Once the glue on the bushings was dry, I added the nuts to the axis ends that will hold the leadscrews. The instructions don't make it clear whether the top nut is required if you are not using the springs (which I am not). I fitted it anyway, and will remove it if it causes trouble later.

I screwed the leadscrews home, and was about to fit them to the clamps when I remembered I needed to add the tubing.

This goes around the motor shafts, and helps to eliminate wobble when used with the new clamps. I would recommend fitting it to the motor shafts before fitting the motors, rather than after - it would have been much easier! I had also fitted the motors with screws and washers, and decision that would come back to haunt me a little later.

I fitted the couplers to the motor shafts, and then propped the gantry on a small box so that I could screw the leadscrews into the couplers.

I screwed the leadscrews as far into the coupler as they would go without being forced, and tightened the screws. The coupling feels very solid and secure now it is all done up - I doubt I'll have any trouble with them coming undone or breaking! I removed the box and levelled the gantry.

The next job was some work on the X axis. I fitted the pulley to the motor.

Then I tried to fit the motor to the axis end. However due to some mis-calculation somewhere, I had run out of M3x12 screws. I removed a pair from each of the Z axis motors (I'll replace them later), and used them to fit the X axis motor in place. The "bulkhead" that mounts the motor to the x axis end is thinner than the Y and Z axis mounts, and the screws bottomed out. I added an extra spring washer to each one and tightened them up.

Lastly I snapped the remaining bushings in place and glued the X carriage to them.

Lastly, the problem I mentioned earlier. While mounting the X axis to the leadscrews,  I noticed something was a bit wonky. It looks as if the lower bed plate may have shifted whilst it was re-gluing, and has become wonky. I really don't want to have to do it again, but might have to if it is too bad. I'll wait until I fit the upper bed to see how badly misaligned it is.

Next up: fitting the X belt.

Chapter 10 - In which I cheat a little, and things get back on track

Things are starting to look up - I now have all of the parts I need to finish my reprap, with the exception of some hot end bits (I think). The major cause of the delay was bought on by myself. In a bid to reduce the cost and number of surplus fixings I'd be left with, I opted to purchase the majority of the components I need through the company I work for. We use a vast array of fixings and electronic components, and I was able to get hold of almost everything I needed. Placing the order, and picking all the parts too longer than expected, but now it is all done I can crack on with the build.

Here are the majority of the parts I purchased:

Mechanical parts

Electronics

The microswitches in the first picture have 90 degree arms on them, and will need to be modified before use as endstops. They were more expensive than most of the others I looked at on the web, but they are good parts. They're UL and CSA approved, and are rated to switch 15 Amps. Whilst I'll never need that much, it provides a margin for error, especially if I end up with a firmware that doesn't use the processor's internal resistors. Speaking of processors, I purchased that too but haven't got a photo yet.

I got back to work by attaching the Y axis stepper motor. We don't carry M3 by 10mm screws at work, so I got 12mm long ones instead. I knew that the motor screw holes bottom out and that 12mm would be too long, so I got some spring washers to take up the slack.

The screws fully seated - you can see the slack caused by them being too long. The bottom screw has the spring washer fitted.

Next I fitted the pulley to the motor shaft. I had gotten a couple of pointy grub screws, thinking that flat ended ones wouldn't grip the shaft well, but hadn't looked at the screws Nophead had supplied. These turned out to be pointed as well, so I kept them (thanks Nophead!). I aligned the pulley with the bearing and tightened it into the shaft before checking that it gripped well and didn't turn. At the same tie, I moved the Y axis bearings closer to the middle of the frame. They were a way off to one side, and I was worried about off-centre forces affecting the movement of the axis. I brought them as close to the centre as possible.

I realised I had forgotten the plain washers behind the spring washers. I went back and fitted them.

I wrapped the Y axis belt (the shorter of the 2 supplied) around the bearings and lined it up over the lower sheet. I marked where it lay on the sheet, and started to carefully remove the sheet form the Y axis smooth rods. Then, disaster! - the bushings came off. Whilst the superglue had done a good job of holding it while it was flat, it cracked when I started to move it vertically.

I took the sheet off completely and used the opportunity to mark up the clamp holes and drill them.

I glued the lower tray down to the bushings again, and will continue with the fitting and tensioning of the belt when the glue is dry. The only good thing to come of this is that the movement seems a little smoother now I've reglued it. Perhaps the bushings were misaligned when I fitted them initially.

Whilst waiting for the glue to dry, I figured I'd make a start on the X axis. Here are the ends:

The holes are all the right size, so no need to drill anything out. I fitted the nuts into the traps, which was a little fiddly. I used the end of a file to make them lie flat when needed:

I fitted M3x12 screws into the nuts (again lacking in 10s). These seem excessive (although they may have something important to do later), and I think that M3x8 or even 6 would be better.

The visual instructions say to lay the parts out 500mm apart, but for the suggested X axis smooth rod length of 420mm this was too far:

Anyhow, I fitted the X ends to the rods, and tightened the screws:

I built the X end idler bearing onto a 50mm piece of threaded rod, and fitted it, and that's the X axis done for now:

The next job is to level the printer. Mine was a bit wonky:

A pair of plastic rules provided the bulk of the adjustment required, with folded post-it notes providing the fine-tuning.

After adjustment - nice and level.

I have a snap-on adjustable foot in mind as one of my first upgrades....

The preliminary adjustment of the Z rod fixings went well, and I moved on to the upper fixings. I fitted up M3x25 screws as suggested in the assembly instructions, but found they were too long. I hadn't read far enough ahead to spot the note about this! I was on the brink of turning the screws around and trying them in reverse, when I looked back at my parts list. I realised I had gotten the correct amount of 20mm screws, so I replaced the 25s and the rod restraints now fit well:

I test fitted a motor to make sure the screw threads didn't protrude too far - they don't.

The last part of this evening was spent fitting the z rods and checking them for verticality. It was a slightly painstaking process, but well worth taking time over.

So here is the machine after all of today's exertions. I'll let the glue dry overnight, and hopefully tomorrow will see the mounting of the X axis.

Next up: X's, Z's and leadscrews!

Chapter 7 - In which I find a problem

It seems like the superglue is holding, but I haven't tried to remove the bottom plate from the axis yet - I figured I'd give the glue some more time. What I did do however was slide the plate up and down the axis. Primarily this was to check the bushings ran smoothly, but it showed up something else interesting.

This is the right hand corner of the carriage at the front of it's travel:

This is the back right hand side of the carriage at the far end of it's travel. Note the spacing of the plate from the vertex:

The Y axis is misaligned. I had measured and checked and rechecked the spacing of the smooth rods on the rear rod, but apparently not well enough. Although not a big misalignment (somewhere in the order of 0.5 to 0.75mm), it is certainly noticeable when moving the carriage.

I adjusted both the smooth rods on the rear rod by the same amount, to keep them parallel. This is the rear right hand corner after adjustment:

Much better. This step of checking the alignment is definitely worth it.

Chapter 6 - In which I almost did nothing

I still haven't bought everything I need, especially the M3 screws and nuts that I need to mount the stepper motors and the belt clamps. I was expecting not to be able to do anything this weekend, but after a trawl through my modelling toolbox I found a 3mm drill bit and decided to drill the top and bottom plates.

Here is the bottom plate (5mm acrylic, with the protective film still on). I have marked up the corners at 8mm (the larger dots).

I took it to the garage and clamped it down. I couldn't find my other expanding clamp, so I used the vice to hold to the other end in place.

I used a scribe to mark the centres of the holes, and hopefully stop the drill bit from wandering.

I loaded up the 3mm bit and drilled all four corners.

I centred the bottom plate on the top plate and redrilled.

I marked the sides of both sheets, just in case they weren't completely centred when I drilled them. Interestingly, the heat generated by the drilling seems to have melted the protective film around the holes, bonding them together. It pulled apart easily though, with no harm done.

I snapped the PLA bushings onto a long section of smooth rod. They were a little stiff, but a combination of running them up and down the rod and using the heat-the-other-end trick freed them up enough to run smoothly.

I snapped the bushings onto the y axis rods. They were still a little rough running, so I ran them up and down until they were smooth again. I think the smooth rod I am using is not entirely cylindrical. I think it's round enough though, but we'll see.

Being a bit of a perfectionist, I wanted the lower plate to be completely square and centered on the bushings. Any error here will be apparent, due to the clear nature of the acrylic. I spaced the bushings with a tape measure, and used my cutting mat below to make sure they were level.

I used superglue to stick the plate to the bushings (which I hope will hold). I used the lines on the cutting mat again to ensure the plate was well aligned.

I'll check later that the glue has dried and formed a strong bond.

In other news, I ordered the bare board for the electronics this week (ebay again). This particular one is v1.1 (which has some pin assignment differences from v1.2 - I'll have to be careful in the firmware), and has the FTDI USB to serial interface chip (the single surface-mount component) already fitted. This will not only save some time and difficulty, but now I don't have to source the chip separately. it was posted at the tail end of last week, and so should be here monday or tuesday.

Up next: Probably the joys of buying even more stuff.