2.85mm to 1.75mm conversion for original Ultimaker 1, Ultimaker 1+

Since Ultimaker has discontinued the original Ultimaker 1 and Ultimaker 2 as of October 2020, I assume the 1+ is also discontinued even though it wasn't mentioned. If not, I don't think it has much more time left. Anyway, 1.75mm filament is much more abundant than 2.85mm filament and I want to be able to replace the nozzle on the printer into the indefinite future so I found some prints on Thingiverse to make that possible.

The extruder is an adapted version of this model by Roald on thingiverse. I changed it so the filament path is more constrained around the extruder gear at the expense of now needing a little bit of support to print. The advantage of this is that semi flexible materials are less likely to bind. True flexibles are still a bad idea on a bowden setup. I used these M3 thumb nuts but there are printable designs you could also use. The half life of an amazon link is short so it will probably break not too far into the future.

The hotend I converted to this model by Dr. Idee on thingivese. The fan shroud is from this design by Musti. These models were unmodified except rather then screw directly into the holes, I drilled them out and glued in brass M3 threaded inserts.

The hotend itself is now a genuine E3D v6 1.75mm groove mount with compression fitting.

The heatbreak and heaterblock are also genuine E3D. I switched to E3D for the heaterblock so I could use the silicone socks which are a life saver when ye olde blob o' doom inevitably decides to appear. The heatercartridge and thermocouple are reused from the original printer. Even though E3D uses thermistors, the control board for the Ultimaker 1+ is designed to use a thermocouple instead so I didn't want to change that. Also no sense in throwing out a heater element if it still works. Both are compatible with the E3D heaterblock.

I printed everything in Prusament Carbon Fiber PC Blend but you can use any high temperature resistant material. Do not use PLA for especially the hotend parts.

The extruder and nozzle are connected via Capricorn tubing. One might think that regular old white PTFE tubing is just as good and way cheaper. It is only cheaper but not just as good. Pay the small ransom and get the Capricorn, it's worth it.