A month off, Day 13 and 14: Racing for Raceways


While I didn't mention it in previous posts, I was preparing to work on the Voron 0.1's electronics over the weekend. Part of that, I realized, was to have not only the wire, but a way to secure all the wiring so it would be tidy and manageable once completed. While you can find a lot of "cable management" solutions both on online stores and in 3D printing sites like Thingiverse, most of those are limited to managing USB cables and the like in the context of a desk.

For the Voron, however, I wanted something which had a more industrial flare. In control circuitry for manufacturing equipment, you often find a plastic channel with slots on each side in a regular pattern. These cable raceways are used to hold and organize the wire within an electronics cabinet, with the slots providing simple ingress and egress points.

...and tried printing it. I tried several different designs, but most either were so brittle they failed in printing, or broke shortly after removing from the print bed. The problem throughout was that these raceways were all designed as single pieces with no sense of Design To Manufacturing (DTM).

DTM considers the method of manufacturing when producing an object while designing the object, rather than just the final form. Many of the raceways I tried printing last week all were solid pieces, resulting in layer lines at critical point of flexation. A well, well tuned printer can still succeed at those, but often only in certain materials. Like everything in the Voron, I wanted to print using stuff which was resistant to higher temperatures. So ABS it was. The problem is that ABS tends to have inter-layer boding issues which make such thin, flexible areas of the prints difficult.

Eventually, I found some designs which printed the raceway in pieces, so that the layer lines were perpendicular to the axis of flexation. While I had success with those printing, the necessity of using brims on ABS resulted in a clean up nightmare. Even a last ditch alternative which would avoid the clean up issues still had weak points.

After nearly a week of trying, I gave up. Instead, I went back to a printable set of cable wall ties. These are little pyramids with a flat top and holes through the middle. Stick the broad base to a surface with tape, lay a cable on the flat top, route a zip tie through it, and tighten it down. I've used these successfully on other projects such as routing ethernet cable. The Voron 0.1 keeps all the electronics hidden behind two panels, so there's more than enough surface to stick the cable ties.

With the raceway issue sorted, it was time to finally put electronics inside the Voron. The mounting brackets and positioning are all determined by the assembly guide, so there was no guesswork needed. Like the hotend, I was avoiding mounting the electronics as it would leave the project feeling more "real", and less like a bunch of parts.

You'd think I'd be excited by this point, but it's actually been very intimidating. The closer this goes from a bunch of parts to an actual, functional device the more nervous I get that perhaps I've screwed it all up irrevocably. That perhaps I missed some key detail, or bought the wrong pieces, or simply assembled it completely wrong. Avoiding completing this step allows all those potential waveforms to remain uncollapsed and avoid the emotional consequences of failure.

To keep this all out of my mind, I put on some audio dramas. This allows me to work while keeping my emotions fixated on a sci-fi adventure story instead.

Wiring too, was straightforward. While the assembly guide and BOM for the Voron 0.1 used a mix of 18 gauge (AWG), 20, and 22 gauge wire, I used 18 for high current applications, and 20 everywhere else. This is over the specification for a lot of the wiring, allowing a little bit of safety. It helped that the 20 AWG wire was the only high temperature wire I had anyways. The 18 gauge was rated for automotive applications up to 85C, which hopefully is enough for where it's placed. It doesn't get near the hotend, of course.

After another impromptu trip to the hardware store for spade connectors, I crimped lengths of wire to attach the power connections. Each connection was also carefully wrapped in heat shrink tubing for further protection. Since I only had a limited number of colors available in wire and heat shrink, I used a label maker I had previously used on the ethernet project to mark key wires and polarity.

Some connectivity checks with a multimeter later, I felt I could risk powering on the 24V power supply.

And no sparks flew, at first. Without thinking, I tried measuring the mains power coming into the PSU...across the wrong lines. This resulted in a brief spark and a damaged multimeter probe. I should have been more careful, of course, and I can only assume I was thinking in DC when I should be been thinking in AC.

Fortunately for me, the probe was still usable, but now nothing seemed to be working on the PSU. After a few panicked minutes thinking I destroyed either the PSU, my multimeter, or both, I realized that the IEC power port I used had a 10A fuse. I pulled it out, and sure enough, it was blown to heck and back. Fortunately, I had one fuse left, so I was able to replace it. As a bonus, we tested the AC fuse production!

Once replaced, I was able to verify that the PSU and the 5V converter for the Raspberry Pi were both working as expected.

Normally, you'd think I'd keep going to connect up the hotend, but, as you can expect, there was another problem.

I was hoping to use the same heater cartage and thermistor used on my Ender 3 for the Voron. This would allow more easily servicing of these parts as they'd be interchangable. Of course, this was never going to work.

The problem is that the Dragon Hotend I bought requires a special, E3D compatible, metal-jacketed version of the thermistor, rather than a simple glass bulb used on the Enter. Thus, the heater block doesn't have a set screw in the correct place. I went and ordered what I hope will be a suitable version online, as well as the recommended heater cartage. The problem is, however, neither will arrive until the end of the week.

If I were working, and not in the middle of an entire month off, this wouldn't be an issue. Instead, now it feels a whole week is going to be wasted on this project in waiting for parts.

I guess I'll have to find something else to do...