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Which bowden and collet/retainer for UM2 1.75mm conversion?

Posted: March 24th, 2018, 8:17 am
by reibuehl
Hi all,

I would like to finally finish installing a 1.75mm extruder as a second extruder on my UM2. I have already installed the feeder motor, a mirrored version of the IRobertI feeder and a 1.75mm hotend. The only thing I am missing is the bowden from the feeder to the printhead. I think that a number of people here have converted their UMs to 1.75. What did you use? A 1.75mm bowden with special collets? A 3mm bowden with a inner 1.75mm bowden and regular collets? If the second option - how do you ensure that the inner bowden doesn't slip back and forth?

Hope you have some ideas to help me finish the conversion!

BTW: I plan to use only one hotend at a time and remove the nozzle from the unused one - both hotends have Olsson blocks installed.

Re: Which bowden and collet/retainer for UM2 1.75mm conversion?

Posted: March 25th, 2018, 4:06 am
by Anders Olsson
I used a regular bowden with an inner tube to fit the 1.75 mm filament and than the regular collets/clips.

I can't remember if/how the inner tube was fixed, I think there was something in one end f it to prevent it from slipping, Carl/3DSolex might be able to answer as he provided that bowden tube.
Anyway I don't think that the inner tube slipping is that much of an issue, the main direction that the tube would like to slip should be in the feeding direction and the PTFE should stop it in that direction.

Re: Which bowden and collet/retainer for UM2 1.75mm conversion?

Posted: March 25th, 2018, 5:25 am
by reibuehl
Great information Anders. Thanks!

Re: Which bowden and collet/retainer for UM2 1.75mm conversion?

Posted: March 27th, 2018, 8:46 pm
by Meduza
I used a 2/4mm standard PTFE bowden tube (bought from E3D), 4mm couplings (https://www.aliexpress.com/item//32839845677.html) and a printed top part for the print head: https://www.youmagine.com/designs/um2-p ... -filaments

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