At the time of writing, I’ve been intermittently working on the construction of my MendelMax 3D-printer for about two months. Much progress has been made (functional electronics! Fully assembled frame!), but lots of things have also gone horribly wrong. In many ways, the approach I’ve taken to building a printer (namely, self-sourcing as much as possible) is less of an exercises in engineering/building things, and more of one in very online shopping. When I have the correct quantities of the correct components, assembly is very easy; figuring out what to purchase is the source of all difficulties so far. A kit would have made this whole project much faster and less stressful.

Frame Construction

I sourced all of my printed parts from TechPaladin. Unfortunately, one of the frame corners had some major issue with layer separation and was completely unusable. Nate, TechPaladin’s proprietor, responded to my email about the issue within 15 minutes and sent a complete set of new frame corners the next day. I’m not sure if I recommend TechPaladin as a source - they’re cheap, offer good customer service, but the print-quality is disappointing (expect to spend some time cleaning prints with a dremel). Additionally, all of the rod holders and holes for washers are much too small. I’m not sure what’s up with the rod holders, as I ordered the 8mm prints and have 8 mm rods… The 1 cm M3 screws included in the official BOM are far too short, and so I had to place a second order for 16mm M3s as well. In terms of tools used, I found that my jeweler’s saw (with 2/0 blades) was ideal for cutting all of the steel rod, and the recommended tap was awesome. Vice-grip pliers served as a functional replacement for a tap-handle.

Electronics

The battle on the electronics front is mostly unchanged since my previous post. I did go with real Polulu stepper drivers instead of the step-sticks I was previously considering building. N.B. that SparkFun sells the perfect set of heat-sinks for stepper drivers, although the included adhesive tap is really annoying to apply. Replacing the incorrect female headers included in the original BOM was infuriating but straightforwards.

Progress on the SMD optical-endstop boards has been a little slower than I would have liked - I accidentally ordered transistors with the wrong electrical characteristics and pinouts, and then made a revision or two with the wrong pinouts. Such problems have been remedied, proper transistors (electrically equivalent to the functional through-hole prototype) are on order, and I expect to finish the construction of three working boards by the middle of this week.

Hot End

I was originally planning on making a knock-off of the Budaschnozzle, but the parts machined out of aluminum were out of stock at Lulzbot, and all local machine shops quoted rather steep prices. It now seems that Lulzbot has realized that it makes little business sense to sell the tricky-to-source components, and so I’ll just buy a completed unit.