MK4 Nextruder PC4-M5 PTFE tube adapter with longer stem - collet style

The stem on the PC4-M5 festo fitting is quite short and I have had trouble with filamant getting caught on exposed threads during loading.   To eliminate this source of MMU failures, I've made a replacement with a longer stem to ensure the filament gets past the internal threads.

I've seen a few adapters that are threaded to accept M6 or M10 threaded fittings, but I don't like the extra height, so my adapter is designed to use E3D style collets instead of a full pneumatic fitting.

I've encountered 3 different outside diameters for PC4 collets and am providing models for each:   5mm, 6mm, and 6.6mm. Note this is the required hole size, and not always the quoted collet outer diameter.

For standard 5mm E3D collets and spares from the MMU3 kit, use the 5mm one.

For standard 0.25" UM2 collets, use the 6.6mm one.

For https://www.printables.com/model/599675-mmu3-cassette-ptfe-fitting-collet use 6mm

For https://www.amazon.ca/dp/B0CQNJSX38, which is advertised as 6mm,   use 6.5mm 

 

Printing

0.4 nozzle
0.15 layer height 

Due to the small size of the stem, ensure you choose a filament that has good inter-layer adhesion.  This can vary by type and brand.  High temperature tolerance is not needed unless you print in an enclosure, in which case I wouldn't use PLA.

I've tested Prusament PETG and Taulman Bridge Nylon with the PrusaSlicer MK4S 15mm structural preset.   

When printing only one or two of these alone, I recommend using a full height draft shield to allow extra cooling time on the stem.  Without the extra time in between layers of the thread, the nylon test melted into a blob.