Pneumatic Fitting Tubing Brake for 3D Printers

I created a printable device to completely eliminate movement of the Teflon tube within the pneumatic fitting and also allow for free movement of the filament within the Teflon tubing.

I have not noticed a problem with the tubing moving in the fitting. In your experience, is this a common issue?

The fitting by nature is only designed to restrict movement in opposition to the air pressure. The forward drive and then retraction causes a sawing effect where the metal teeth grasp the Teflon tubing. A groove will wear and the tube starts to move more and more during retraction. This a know event and there are several other varieties of fixes for the phenomenon on Thingiverse. With that said. I feel this is a very good printable device to completely eliminate movement of the Teflon tube within the pneumatic fitting.

I have not noticed it, but I haven’t looking either. Mind you, I’m now using a Micro Swiss all-metal hotend + extruder. It uses a C ring to hold the tubing in place. I guess that would eliminate the issue.

The Blue Ring always seems fine on the hotend for me, but on the extruder end gets all the torque. I have noticed how the extruder end of the tube gets grooved, sometimes even hard to get out. I noticed while doing a piece with heavy retraction, that the tube was moving in and out a little ways, not much, but enough I felt it was probably effecting the desired effect at the hotend. Keeping the filament cool before it hits the tip and a solid Bowden tube connection ensure that the desire retraction effect of the filament is obtained. Otherwise you have marshmallow effect with the filament and it basically gets dampened out with the movement. I have a stout cooling fan setup now and I noticed right away how much of that effect it lost just being cooler. So I guess you might say this is a silly piece to some, others might say that it assures them there is a solid connection, and that only the filament is moving and not the filament and tube.

I never actually thought much of it until then. It was nothing other than an annoyance I assumed came with the territory. Then a week or so ago, I accidentally ran across one. It was the kind with 2 halves and a big hollow center nut to tighten them. I tired it, and I noticed a difference right away. It was kind of cumbersome and and while it indeed placed a wedge behind the push to release button and locked it, it could still allow for movement of the Bowden tube itself. I felt any movement could still grow and become noticeable. My device surrounds the fitting so it becomes one unit. That unit then attaches to the original location. Now the entire connection is fastened and static.

Thanks for the design! BondTech acknowledges that its dual-geared extruder does not play well with Capricorn tubing. The printed inserts I use can, after time, fall out. This looks like a more sturdy soltion. Going to print it out.


I use the CHEP method which he adopted from someone on the internet. I have only a short piece of Capricorn tubing jammed into my hot end between the nozzle and the the retraining bolt with the tubing coming through it and unlike CHEP I don’t use a retaining washer to guide the tubing as they butt together. It works fine for me. Will soon try printing my roll of PETG and see how it does with that.

The hot end of the tubing is not addressed with my device, it’s for the DRIVE end of the tubing. The hot end doesn’t get that much torque on it. The drive end does, and that is where you see the grooving and movement.
However I will say that with my device installed you won’t have any issues with the hot end anymore if you did previously. My device removes any chances for movement of the tube.