Improved Flexible Filament Extruder Upgrade CR10, CR10 Mini, Ender 3

by Elproducts Aug 28, 2018
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It seems that the hole to screw it in is slightly too small. On the other hand the hole for the Boden tube is slightly too big.

I have the exact same problem... have you found a solution to this? I was just going to glue the tube in and drill out the coupler end and tap it as best i could

I decided to go with the stock extruder. If all speeds are set to 30mm/s or less in Cura and retraction is disabled, TPU prints very well even on the stock printer. I guess one could heat the coupler and then attempt to screw it in. That might work.

do you print this with PLA or PETG? and how much of infill please?

I used PLA at 50% infill

crap. video restricted. F*** Youtube!

Unfortunately this didn't work for me. Thankful I'm in the minority since it seems to work so well. It printed fine, installed fine, but the extruder gear would not make enough contact and kept slipping, therefore I was getting under/no extrusion. Already have filament guidewheels and arms, and filament inserts, so the filament being too tight was not an issue. Even tried using spring wedges to increase the gear tension, but it was just not having it. Ender 3 Pro

Will this work with a metal extruder?

For anyone struggling to get it to thread in straight, dip it in some hot water for 30 seconds or so to soften the plastic and then it'll go right in

You can also put the coupler in a vice facing threads up. Heat the threads for a few seconds with a little torch lighter, and then carefully twist the printed piece on to start the threads. Once it cools just use a wrench to finish it off with the 2 steps forward, one step back method like you are tapping the hole..... alternatively just tap the bloody hole lol

This technique worked for me. I had separated the coupler and was resting it in a teacup of boiled water in between attempts. Did take quite a lot of convincing, though.

Well, there went about 6 hours of my life trying to make that work. I tried 5 different pieces of capricorn cut at different lengths and angles, and no matter what I did I couldn't get TPU to extrude consistently. Even at extremely slow speeds. Not saying the part doesn't work, but I tried everything to no avail.

When I tried, I noticed my problems occurred during retraction; the filament didn't bind during feeding, but did end up getting caught up when retracting. So I made this: https://www.thingiverse.com/thing:3488175

Isn't there a small chance that on retraction the gears pull the PTFE out the hole and into the gear?
Wouldn't be better just to extend the part or it would be too flimsy?

Retraction needs to be turned off when using flexible filaments.

Works really good on Ender 3. Printing TPE with no problems.


Great. Thanks for the feedback.

I printed this on my CR-10S and it looks great! The PTFE tube doesn't pressure fit into my plate, though. It easily slides in. I printed a 20 mm calibration cube and, with my calipers, it measured 20.05 mm, so my tolerances seem pretty good. Is that enough to loosen this fit? I'm using the extra PTFE that came with my CR-10S, so maybe it's a little small.

Did anyone else have a looser fitting PTFE tube? Thanks!

I confirm that the stock bowden tube is, indeed, a bit smaller. I wrapped it with a piece of tape and it works flawelessly so far.

The Creality PTFE seems to be a bit smaller. I used Capricorn tubing which is exactly 4mm.

Great! Thank you for the reply!

What slicer, what settings?


Glad to see you decided to give it a shot. Hope it comes in handy for your future projects.

I don't remember. It's in the video.

how fast can you print TPU with this mod?!

I wouldn't go faster than 30 mm/s. I actually use 20 mm/s.

I am curious. Do you print this as it is laid out in the pics? Also did you print this without supports due to the threaded hole and I plan on using ABS? For strength would you recommend 100 percent infill?

Yes. Flat as shown. No supports, 50% fill.

Does this have any impact on printing PLA etc? I assume you get the same quality as before? Nice mod, BTW!

Prints exactly the same as before the mod.