PTFE connector sealed backplate

thingiverse

I take a remix approach to TypQxQ's PTFE connector, adding an o-ring to seal the inside of the box more effectively. The original PTFE through design held my tube firm in both directions, which I really appreciated, but air leakage through the connector was far from ideal. As a bonus, the o-ring allows the PTFE to rotate in the connector without breaking the seal. I design it around 3.8mm x 7.6mm x 1.9mm Buna-nitrile o-rings that worked well for me before with PTFE tube end caps. My supply came from an assorted pack, but you can find this size in packs on Amazon (https://www.amazon.com/gp/product/B00595MG6M). Starting with the "thicker plastic" backplate of the original, I make the base a little thicker and recess a pocket. Into the pocket, place an o-ring sandwiched between two "caps." A little bit of glue to secure the outer "cap," and you have a tight seal around the tube. With these installed, I can now get enough pressure in my Rubbermaid 21 cup spool boxes to pop the lid loose. Leakage from this joint should be negligible over time. The reason for not integrating the inner "cap" into the backplate body is that the concave side needs to be on top (not an overhang) to be clean enough to mate to the o-ring. I could have flipped the backplate upside down, but that would have led to tons of support material.