I have been working with open source 3d Printing as a hobby for a while now. I built a McWire printer from mostly hardware parts, and printed my Mendel with it. I have worked with a lot of people in the process, and helped them work on their 3d printers as well. There is one critical part of the whole thing that often fails for people which is known as the “Hot End”. The hot end is the portion of the printer that melts plastic at a precise temperature and allows it to flow through a tiny aperture under pressure. I have tried every design and variation I could get a hold of:
the standard old threaded insulator with an M6 bolt that is heated: using Peek, PTFE, and hybrid insulators, M6 bolt/nozzle, M6 bolt + separate big head nozzle, direct nichrome wire, threaded bushing with nichrome wire. Every combination between them.
These all had the same problems:
- Filament would get too hot too far up melt and jam.
- Pressure would blow the M6 brass bolt out of the insulator barrel
- separate parts would often leak
- heat traveled up to the printed filament drive block and started melting parts.
I also tried several experimental designs including ones with 1.75 filament… they all share the same principals:
- you want to keep the filament cool and rigid as far down as you can.
- You want to heat as little as necessary just before it exits the nozzle
- You don’t want any friction impeding the filament getting to the nozzle
- YOU CANNOT RELY ON THREADED PEEK OR PTFE FOR STRUCTURAL INTEGRITY WHILE HEATED
- nichrome wire is tricky to apply, and burns out
I have found 2 designs that meet my criteria
I think the Adrians ones are reliable, good designs that you can improve upon as you see fit.
The Arcol.hu one is an “Over engineered” thing of beauty.
I am now running the arcol.hu hot constantly. I do have a slow leak which I expect I can fix with PTFE tape, but besides that the thing is simply performing extremely well. It keeps cool where it should, it gets hot where it should and quickly. It pays a lot of attention to supports. There is a PTFE tube going down the middle to minimize friction. The kit is WAY more complete than anything I have ordered for my 3D printer from anywhere. Cables, shrink wrap, extra insulation, fire cement, all things I would have expected to need to have on hand were in there. One of the things that impressed me the most about this design is how much care was paid to the wiring. I haven’t seen that in any other design. It’s usually left up to discretion, but this one has a nicely engineered solution built in.
I was concerned that the heater block was tilting downwards. There happens to be an M3 tapped hole in the heater block that lines up perfectly with a hole in the lower support wafer, so that was easily handled by using its existing design.
The print quality that this produces as at least as good as anything else I’ve seen of similar technology, including UP printers. It’s smooth and consistent.
I would recommend this component to ANYONE building a 3d printer, but I would especially urge anyone who’s sick of dealing with extruder troubles to sign up for the next batch to be created.