Collet clamp for 4mm PTFE (bowden) tube

thingiverse

PC connectors are nice, but they require a backstop since they only lock in one direction. This is (mainly) why I designed these collet clamps for the 4 mm PTFE tubes. The other reason was the horrible handling of Prusa's original buffer for the MMU2s. Don't get me wrong - it's a nice solution that uses minimal space, but since I had the space available (see picture), I had no reason to keep on fighting with fiddling the filament through the buffer and from the buffer to the MMU. What is it: Feedthrough and the Feedthrough nut provide a path into the printer box. The tube from the MMU goes into the collet and out through the end of the feedthrough. I recommend vertigo235's PTFE holder https://www.thingiverse.com/thing:3233579 on the MMU end. The angled base is intended (haven't tested that setup yet) to go at the bottom of my filament box, with a short piece of tube, as the spool side end of my filament buffer. It should serve the same purpose as the short end of filament in Prusa's original buffer, i.e. prevent the filament from pushing back onto (and then off) the spool when unloading. The free space (to be subdivided by some plexi sheets) between the feedthrough and the base acts as filament buffer. Each of the feedthroughs and bases will take a collet and then be closed off with an upper nut, which serves to compress the collets into their respective holders. Handle the collets with care (e.g. DON'T try to roll them between your fingers) as they break easily. In the picture of my setup above, all these things are not installed yet - which is one of the main reasons for that tangle of PTFE tubes at the back... Materials: I printed the feedthrough, holders and nuts from various colours of PLA and the collets (as inspired by QuadeHale's Collet Drill Stop https://www.thingiverse.com/thing:3177276 ) from PETG. Print a few more collets than you need (see above) as you may not even get all of them off the bed without breaking them. Printing: Feedthrough: with the shaft pointing up, i.e. standing on the collet side end Feedthrough nut: flat side down Base: lying on the back, with the thread pointing straight up Upper nut: with the open side up Collet: standing on the longer end