Keith's Electronics Blog

A few notes on assembling the printhead:

The 2.4r2 assembly manual has much more detail than the 2.4r1, very much appreciated.

Even the 2.4r2 manual leaves it to you to figure out how to assemble whatever hot end you have. Because my kit came with an E3D-v6 clone hot end, I found these self-proclaimed outdated E3D-v6 assembly instructions that direct you to better-maintained instructions that no longer exist, and followed the link within these instructions to another set for installing the old-style thermistor.

The 2.4r2 instructions and their diagrams don’t speak to this detail, but later assembly makes it clear that one does leave the (here black and barely visible) plastic ring that guides the PTFE tube into the cold end but one omits the (here blue) clip that in some uses locks the ring onto the PTFE tube.

After measuring and marking the PTFE tube length, I should have cut it with my PTFE tubing cutter but I was impatient and cut it with diagonal cutters, then mashed it round again. I look forward to regretting that later.

I’ve completed the printhead assembly and have yet to figure out what is meant by this instruction when mounting the hot end to the X carriage:

INDEXING BOLTS
The bolts are used to index the tool cartridge. Leave them slightly loose so that the cartridge can be slid out.

The 2.4r1 instructions make no mention of where the pinion gear should be positioned on the motor shaft. The 2.4r2 instructions give a dimension and also appear to show a printable shim that will position it correctly, which is a fantastic idea (though I didn’t download the STLs and print it myself).

The white nylon drive gear in my Fysetc kit wasn’t installed fully into position at the factory; you can see a bit of splined shaft between the hub of the nylon gear and the Bondtech-style filament gear; and you can see that the filament groove is misaligned between the Bondtech-style gear and the housing. I took it back out, supported the back end of the nylon gear with a large nut, and pressed it the rest of the way into position in a bench vise.

There’s just barely room between the 4020 blower fan and the printed housing to leave the fan wires routed through their factory strain relief, differently than shown here. You should do that. So you don’t break off the fan wires. Like I did. And have to solder one back on.

After reattaching and routing the wires back through the strain relief, I covered the solder joints with hot glue to provide extra strain relief. I did note first that the black surface immediately beneath the wires is the fan and that it’s probably counterproductive to fill the whole cavity with glue.

Since I’d removed the sticker to have a teence more room to solder, I added a couple of drops of lightweight oil to the fan shaft before closing things back up.

The instructions and diagrams are hard to read regarding the orientation of the (lower) 4010 fan; but sticker-side-in blows air onto the cold end rather than sucking air past it, and more importantly, looks better.

I presume the little notches in the toolhead housing are for cable ties (which I have since trimmed).

I took a break from Voron assembly last November due to being quite vexed at crucial information omitted from the assembly manual and the extra effort in interpretation and rework it caused me.

With a little one on the way [that is, I just ordered a Voron 0.1 parts kit], I figured it was time to get the 2.4 assembly finished; and thankfully, since November the assembly manual has been overhauled from r1 to r2 and is much, much, much better. If you’re assembling a Voron 2.4 and you don’t already have the r2 assembly manual, go download it right now. You can thank me later.

Before my hibernation, I had assembled and installed the gantry. All of my frustrations about the instructions that drove me away at the time have now been addressed, save one, presented here for your sanity:

The instructions say to route the AB belts by clamping one end onto the carriage, then threading them through the entire gantry, then clamping the second end onto the carriage. I tried that at least twice and found it difficult each time to fish the belt ends through the AB blocks in the back corners. It was much easier for me to start in the middle by pushing both ends of each belt through this opening and around their drive pulleys, then threading the belts outward toward both ends.

As I resume assembly, I’ll compare 2.4r1 and 2.4r2 instructions, only calling out issues with the r2 instructions.

At the time I purchased my kit and at the time I printed my parts, the Fysetc bill of materials for the Voron 2.4 kit listed the specific part number of Igus drag chain, so I printed the Igus chain anchors (upper right) from the Voron parts repository. The chain that shipped clearly doesn’t fit those anchors; so I’ve now printed the generic chain anchors (lower left) from the repository, which I see I positioned for the photo 180° from their proper orientation.

I don’t mind at all when a kit assembler makes equivalent or better substitutions from the original BoM. I do mind when they state or imply that they’re providing one part and they provide another.

Case in point about not minding a substitution, Fysetc clearly calls out that they’ve provided an X-Y limit switch PCB accepting a single cable rather than separate limit switches requiring soldering and DIY cable; and they provided a link to a new limit switch mount to use with it (lower). I’d already printed the mount for separate limit switches (upper) before noticing this; no big deal.

Assembled, it’s sleek and cute.

It does differ from most of the Voron assembly in that it looks to me like it’s made to be installed with flat- or oval-head screws (countersunk on the back side of the head) and there are none in the kit. I made do with M3 sheet metal screws, which are loose in the PCB holes but cinch it down fine when tightened; but for someone who doesn’t have a supply on hand, this could cause an extra trip to the hardware store.

The Voron 2.4 has a “CoreXY” drive system, meaning instead of having one axis’s stepper on a gantry moved by another axis’s stepper, it has two steppers in the back corners connecting across the Y rails and the X gantry to the printhead with a complicated routing of two belts, to reduce mass of the gantry and facilitate higher acceleration. Turning a single stepper would move the gantry diagonally; so the two steppers work together to perform Cartesian moves and are called A and B instead of X and Y.

The instructions have you insert these two M5 machine screws as well as three M3 machine screws before building the A and B blocks’ idler pulley stacks; but there is no earthly reason to insert the M3 screws until after you’ve built and secured the idler stacks and you’re ready to attach the steppers, so just don’t.

The instructions omit that the steppers need to be installed with their cable connectors in this orientation 20220601 edit — with their cable connectors facing toward the center of the back plane of the printer.

The instructions again tell you to put the pulleys on the motors with threadlocker as the first step of assembling this stage, before assembling the blocks and installing the motors onto them. No. Again, no. It’s only a wee bit inconvenient to wait until the motors are affixed to the blocks before installing the pulleys, and it allows you to align the drive pulleys to be planar with their idlers, which seems important.

One timing pulley is installed teeth up, the other teeth down, corresponding with the position of the single idler pulley on each block.

If you want to criticize the print quality and fit of my Voron parts, you could rightly do that … or you could reflect on the fact that what I’m doing here is assembling a new, better 3D printer.

The 350-mm-square build plate is a big boi, massing 3 kg.

Big enough to hold a Prusa.

Being a little bit … detail-oriented … I clamped guides onto the underside of the build platform to ensure good registration of the adhesive heating pad.

The Fysetc kit came with the thermistor already adhered to the underside of the heating pad. This seems not ideal for accurate temperatures and for accurate PID tuning of build plate temperature, especially with so massive a build plate. I tried prying at the thermistor’s adhesive pad and quit trying for now; but I may need to relocate the thermistor later to outside the footprint of the heating pad, to at least measure some thermal conductivity through the build plate. May even need to buy a replacement thermistor if I can’t extricate this one intact.

It’s easy to loosen the build plate screws and slide the plate back and forth on the deck rails; and I understand that (although the assembly manual doesn’t mention it) a calibration step will be positioning the Z limit switch underneath the back end of the Y travel and then scooting the build plate as far back as it can go without touching the Z switch assembly.

Accordingly, it would be a mistake to cover up the build plate screws with the Fysetc kit’s adhesive-backed fridge magnet that holds down the spring steel build sheet. Although it is true that once assembly and calibration are complete, I don’t expect to need to move the build plate again, it is also true that the spring steel sheet will still stick well to the fridge magnet with a hole in the magnet above each build plate screw. Whose positions I marked on the magnet before installing the build plate on the frame.

Finally, I’m thinking about ways to minimize heat transmission from the build plate to the deck rails. No need to heat up the rails, and particularly no need to heat up the acrylic deck plate, which I hear has a reputation for warping from the heat. It’s probably only a small improvement, but I’m planning to replace the black oxide machine screws holding the build plate to the deck rails with stainless, as I understand stainless has a lower thermal conductivity. I’m pondering searching for ceramic standoffs instead of the provided knurled knobs of unknown metal; and I’m thinking of sliding aluminum bubble wrap insulation between the deck plate and the build plate.

The Z motor mounts have been revised (shown here) since the assembly manual was prepared (not shown here).

The assembly manual shows, but doesn’t emphasize, that each motor’s cable connection needs to face as shown here relative to the mount or the cables will be unhappy later.

The assembly manual instructs you to install the pulleys on the Z motors with threadlocker on the set screws as the first step of Z stage assembly. If you do, you won’t have any reference to align the motor pulleys with the 80T pulleys and they may be nonplanar, which the belts really won’t like.

Save motor pulley installation until motor installation; leave the pulleys loose while bolting down the motors; and install threadlocker and tighten the set screws after the motors are installed and tightened to the frame. You can ensure proper pulley alignment and it works fine.

No amount of optimism will make the M5 machine screws fit into the slots in the DIN rails. The earlier one files that out, the better.

No amount of optimism will make the giant screws that came in the rubber feet fit into the M5 nuts trapped in the Z pulley assembly. The earlier one figures that out, the better.

The first stage of assembly after the frame is the pulley set for the Z stepper in each corner of the printer (four Z motors, and belt-reduction, and belt attachment to the gantry). The instructions call for the 625 bearings and the GT2 20T pulleys … so which of these unlabeled bags would those be?

Well, I can rule out the bags with two and three parts, since this needs four. I can rule out the spool-shaped pulleys since that’s not what’s shown in the instructions. That leaves two sizes of pulleys and it must be the larger, as a nearby assembly step calls for the 18T pulleys, which one expects to be smaller than 20T pulleys. And from the published dimensions of 625 bearings, they must be the larger, whose size relative to the 20T pulley does match the assembly diagram.

The shaft is longer than the stack of pulleys, bearings, and shims, so where to position the pulleys within the stack slack? I opted for squished to center as tightly against the shims as possible; and this works out to have been a good choice, as the black 80T gear comes very close to the edge of the recess on this part and its mate, so moving it toward center and keeping it from sliding around are important.

The printed Voron parts make extensive use of threaded brass heat-set inserts. I’d installed a few before using my regular soldering iron; but with as many as I need to do on the Voron, I sprung for a cheap brass insert tip made to fit low-end Weller and Hakko soldering irons. Since I didn’t have any low-end Weller soldering irons, I also sprung for one of those.

The heat-set tip is a loose fit into the inserts so that it doesn’t drag them back out of the plastic, therefore it doesn’t at all pick up the inserts off the table. After thinking through some bad ways to get the inserts onto the heated tip, the perfectly workable approach is to set the inserts onto the workpiece, spear them in place with the iron, straighten, let them heat up, and let just the weight of my hand slowly sink them into the plastic.

The process does displace plastic around the pilot hole and raise it above the level of the surface. So (left) I’m being careful to sink the inserts down until they’re flush with the original surface and (right) I take a few passes on the 180-grit sandpaper to remove the resulting volcanic cone.