I'm done putting the printer together structurally. Here's what I've learned so far about the easiest order in which to assemble it. I wound up putting it together and pulling it apart a good four or five times before I figured out the right order, so hopefully this will save others some time.
I ordered some color-coded heat shrink tubing to make things easier. The black stuff works too.
You may want to buy some Astrosyn dampers for your motors. The metal frame is quieter than the "speaker box" of a Rostock MAX, but it's still loud enough to be heard from behind a closed door.
First things first: Don't bolt the motors or any of the 3D printed/lasercut pieces to the frame yet. The belts can't be installed with the motors in place, and the PSU/electronics mounts will get in the way if installed too soon. The following instructions should be followed
in order.
Frame bottom and sides
- Route the wires through the center (round) part of the vertical T-slot rails first, before you bolt anything to them. Leave enough spare wire hanging out of each end to reach to either of the neighboring towers (plus ~2-3" extra, which you'll need because the wire will be twisted later). I think I bought 20' of that 8-conductor stuff on http://tricklaser.com" onclick="window.open(this.href);return false;, and that was enough with some extra to spare. (I wound up needing the extra.)
- If you need to use any tee nuts that aren't the roll-in kind (they have to be installed through the ends of the rails), put them in place now. The only roll-in tee nuts I'm aware of that work with this frame don't take the screw size that the printable/laser-cut parts require.
- Using the supplied two-hole tee nuts, LOOSELY bolt three horizontal (double-wide) T-slot rails to the bottom of the vertical rails, so that the bottom edges of the rails sit on the alignment pins. (The bottom of each vertical rail is where the holes are drilled for the steppers.) Don't tighten all the way - the frame should feel a little loose. Don't bolt on the top three rails just yet, either.
- Make SURE that none of the T-slot nuts you put into the horizontal rails are sitting at or near the rail-ends. It's really easy to tighten the rails down, and then discover that a tee nut is lodged in there. It won't budge after the rails are tightened, trust me.
- Tolerances are tight, so you'll probably have to "persuade" the rails to sit directly on the alignment pins. DON'T use a hammer. If you absolutely must, use a small (hammer-sized) rubber mallet. Better still, ball your fist and use the bottom edge (where the last finger/meaty part of the palm is) with the least force necessary to seat the rails. (Don't put your back into it - you really just want a little force.) The objective is to get it to where no light (direct or reflected) can pass between the rails and the pins. If you see even the tiniest amount of light making it through, you have a gap that needs closing.
Carriages
- Assemble the Trick Trucks according to the video on the Trick Laser store page. Note that the BOM specifies one too few washers for each wheel, if you were to go by that video. I compensated by leaving out the washer that goes between the screw head and the metal of the Trucks. (The rest of the washers are crucial - you can't leave any out.)
- Don't fasten the plastic U-joint yokes to the trucks yet. You just want the bare metal cutouts with the wheels.
- Slide the Trucks down over the tops of the rails. They'll probably be loose and wobbly. The eccentric cams have notches ground into the narrowest part. Rotate the cams using a wrench or pliers until the Trucks ride tight, but not too tight. They should have no wobble to them at all, but they should still fall on their own if you move them up the rails and let go. If a Truck doesn't fall on its own, rotate the eccentric cam so that the notched side is further from facing inward.
- If you can't get the Trucks properly tight (not even slightly wobbly), even with the eccentric cam's notched face fully inward, it means something either needs to be tightened, or you need to loosen and re-tighten all three of the wheels. I had to do that a couple times.
- As you move the trucks up and down, they should glide smoothly. You shouldn't feel like something is grinding or chattering inside any of the wheels. If you do, something is too tight and needs to be loosened. Remember that there needs to be a washer INSIDE each wheel, between the two bearings. If it isn't there, you'll probably have trouble!
- Now, REMOVE all three Trick Trucks from the towers. The point of installing them here was to verify that they were capable of gliding smoothly, but we can't connect the belts to them while they're still in place. We'll loosen the e-cams and press them into place on the towers later on. (If you forget this step, it's not a big deal - they can be removed later. It's just easier to do this by sliding them off the ends of the rails.)
Pullies & frame top
- Assemble the pullies. I used three washers on either side of the bearings for spacing (they come with the kit), as the printable spacers didn't fit on my printer. The... uh... let's call them "pulley risers" are the metal shanks that stand on either side of the pullies, and they slide into the frame. Take care to assemble them with the angle-ground sides inward - they're ground that way so that they'll fit into the vertical T-slot. Slide the pulley assemblies into the T-slot.
- The pulley risers have been tapped to accept the cap-head Allen screws that come with the kit. They serve the same purpose as the two-hole tee nuts you used to fasten the lower horizontals in the previous section.
- If you're using the printable endstop switch mounts, put two of the SeeMe T-slot nuts into each of the upper channels of the three horizontal extrusions before you mount them.
- Bolt the three remaining horizontal rails LOOSELY to the top of the frame, taking care to seat them on the alignment pins such that no light can travel between the pins and the rails. Again, don't use a rubber mallet unless there's no other way, and don't use a regular hammer at all.
- Now that all six horizontal rails are loosely attached, start tightening them down. Again, make SURE that no tee nuts are sitting at the ends of the rails - you don't want them getting clamped in place during the tightening process.
- I like to make two passes at this: tighten the rails "sorta", JUST until there's no slop, but not nearly as tight as they can be - and then a second pass, where I tighten them down all the way. As you do this, re-check the rails to make sure they're seated fully on their pins, with no light making it between the rails and their pins. They will get jostled a little as the other rails are tightened, and as you move the printer around to work on it. I did this by tightening a screw on one side of a horizontal, then the screw diagonally opposite to it, then the remaining two, and then I'd pick up the printer and rotate it so that the next side was facing me.
- Once you're done tightening everything, do another inspection to make sure no light is visible between any of the rails and their alignment pins.
Endstop switches
- Bolt the microswitches to their mounts first.
- Lay the printer on one side. Place an endstop mount into one of the two corners that are laying flat. Use an Allen wrench or similar to push one of the tee nuts into place, and to align it so that the screw hole is straight up and down rather than angled. Bolt the mount down loosely, and then do the same for a mount on the other side.
- That done, rotate the printer until the side required to fasten the remaining endstop switch mount is facing up, and then loosely bolt that one in.
- Each endstop mount has two bolt holes, so fasten the bolts through the other holes using the same technique.
- After everything is loosely bolted, you can tighten down the bolts. Don't over-tighten them, or you'll crack the mounts.
Endstop switch wiring (Upper)
- I used the following color codes for wire, AND for heat-shrink: X=RED, Y=GREEN, Z=BLUE. The TL 8-conductor wire has red, green, blue, and some other colors.
- Following recommendations elsewhere, I decided to dedicate the 8-conductor wire going through one of the towers for endstops only in order to lower the probability of EM interference causing false triggers. I also decided to use color-coded heat shrink, rather than just the black stuff. I figured that would make things easier, and it did!
- I took two pairs of wires, slid three short sections of heat shrink over each pair, and then used a power drill to wind the wires up into tight double helices. That done, I spaced the heat shrink sections evenly, and used a heat gun to tighten them down. That would keep the wires from un-winding on their own. This procedure makes cable management much easier, and also increases resistance to EM interference. The third pair was cut short, as it goes to the endstop switch right on its own tower. A fourth pair is left unused.
- Using either spade connectors or solder, connect each wire pair to the common (COM) and normally closed (NC) pins on the switches. I slid color-coded heat shrink over each wire at the end of the twisted pairs, soldered them in place, and then slid the heat shrink over the solder joints.
- For now, the wires are just pressed into the lower channel of the horizontal rails. In the future, I think I'll design some printable clip-on thing to fasten them better.
Motors & Belts
- If you bought Astrosyn or other stepper motor dampers, fasten them to your stepper motors now.
- Install the GT2 pulleys to your steppers. Fit them into the motor mounts to ensure that the pulleys are exactly the right distance from the nose of each motor. Once you're sure they're PERFECT, use thread locker and tighten the grub screws all the way. Keep in mind that the Allen wrench they supply is made out of soft metal, and you're only going to get a few full tighten/loosen cycles for each pulley before the wrench starts getting rounded out (and therefore useless).
- Do all three motors before you continue, and verify them all after tightening (with thread locker) before you continue by test-fitting them to their towers. The thread locker doesn't set immediately, so you can loosen/tighten them for a little while after, should you discover a mis-alignment.
- Cut your GT2 belts to length, leaving ~6" extra. I did this by hanging the belt next to a tower to simulate the length between the two pullies, doubling that, and then adding some extra length.
- If you use a length of GT2 belt as a template to cut the other two belts, DOUBLE-CHECK IT. I cut a length too short, and then had to go through and cut three more lengths after I discovered my error.
- Fish a length of GT2 belt down the outward (closed) channel of one of the vertical rails. It should emerge into the cutout for the motor, down at the bottom. Fish it out of there. Install the motor using the 20mm screws that come with the kit. (I used 22mm screws, which also worked fine.)
- Make sure the locknuts holding the top pully assemblies together aren't too tight, and that the pulleys are resting at the lowest position possible. (The pulley risers have elongated slots so that the pulleys can be moved up and down to provide proper tension.)
- Take the U-joint yokes (plastic pieces with endstop adjustment screws sticking up out of them) and install the printable belt grippers (shaped like this: |___|), with the bottom touching the U-joint yokes. When the yokes are installed to the Trick Trucks, this will leave a little channel between the yokes and the metal part of the trucks. Be SURE to trim away any excess plastic from the belt grippers, as the completed assembly has to sit perfectly FLAT. Do NOT screw them to the Trucks yet!
- I didn't install the printable belt standoffs, as they didn't allow the Trucks' wheels to sit in the grooves. Maybe a future rev, or more washers, will fix that.
- With the GT2 belt running over both the top and bottom pullies, bring the belt ends together. The teeth should be facing each other. Sandwich them so that the teeth of each belt half engages with the teeth of the other half. Feed the "belt sandwich" through the little cutout in the middle of each Truck, from the back side (where the wheels are).
- Pulling the "belt sandwich" through the cutout and then upwards (towards the top of the printer), install the U-joint yokes. The printable belt grippers you installed to the U-joint yokes should close around the belts, locking them down to the Trucks. Tighten the yokes down good. There should be some excess belt sticking up. You can trim those down, but keep in mind that the more you trim, the harder it'll be to re-do this in the future without having to buy more GT2 belt. You'll definitely want to remove enough slack to be absolutely certain that it can't get anywhere near where the endstop screws have to press the switches, or get fouled up with anything else.
- Loosen the eccentric cams on the Trucks by rotating the marked side until it's facing all the way outwards.
- Push the Trucks into place on the rails. You may have to mess with them a little to get them in place. That done, rotate the marked sides of the e-cams until the Trucks slide up and down easily, but without ANY slop at all.
- As you slide the trucks up and down, you'll feel a very smooth "notched" response from the stepper motor, as the magnets pass the stators inside the motors many times per revolution. The Trucks will no longer fall on their own because of the motors' internal friction. You should NOT sense any grinding/chattering coming from the wheels themselves. If you do, it means one of the wheels is too tight, or you forgot to put a washer between the two bearings in each wheel. All three Trucks should be tight enough not to have any wobble AT ALL, but not so tight that unneeded extra friction is imparted. That will make the motors work harder, and may hurt print quality.
- Using an Allen wrench and something to hold the locknut in place, move each top pulley up in its groove until the slack is taken out of each belt. I usually use an Allen wrench or a pair of tiny screwdrivers to lever the pulley upwards and keep it under tension. You shouldn't hear a bunch of noise coming from the top pulleys as the belts ride over them. If you tighten a pulley and hear belt noise, loosen it, bring it down a tiny fraction of an inch, tighten it, and try again. Keep doing this until the sound of the pulley teeth riding over the top pulley is no longer excessive.
Wiring (Lower)
- I used the same trick as above - three short sections of color-coded heat shrink, and I wound the wires with a drill. Steppers have four wires, so you can braid them instead, but holy hell, that takes all day! With the drill and some heat-shrink, I got them wound and tightened much more quickly. I did likewise with some "Makerbot connector" wires (the kind with a female connector that hooks the steppers up to the controller). I joined the stepper wires to the connector wires with butt splices.
- To be continued.
That's as far as I've got. The structure is basically done at this point. I haven't installed the rubber feet or their risers - filament flow may have been too low when I printed the risers, because while the T-slots will stand on them, they don't grip the slots and will fall out the moment the printer is picked up. I also didn't install the electronics/PSU mounting hardware yet because without the risers, the printer isn't tall enough to accommodate them, and the frame would sit at a funny angle.
I used SeeMe's T-slot nuts for the endstop mounts because they take screws that are the right diameter for the mounts, an I wanted a tight fit to ensure good alignment. I also installed the heated bed brackets, but as these are keyed to line up perfectly with the slots, I was able to use the roll-in tee nuts with different (narrower) screw threading. I don't think any roll-in tee nuts are available that have big enough threading to accommodate SeeMe's screws, so you have to get narrower ones.
