Universal 50mm Tow Ball Cap

This is a replacement protective cap for a standard 50 mm tow ball, modelled from an original OEM cap in Fusion 360.

It is designed specifically for polypropylene (PP) filament, providing the flexibility needed for the segmented body to snap securely over the tow ball without cracking. TPU 95A is way too soft, even 64D is insufficient. Both TPU's are just too flexible compared to the OEM version. You can still use TPU but the area where the elastic grips to cap/tow-bar, it misaligns as you place it onto the tow-bar.

The cap uses a simple elastic band retention mechanism fitted into the lower groove. The elastic band pulls the flexible segments together, keeping the cap firmly attached while still allowing it to be easily removed when required.

Features

• Fits standard 50 mm tow balls.

• Modelled from an OEM original cap.

• Designed for PP filament.

• Flexible segmented design.

• Elastic band retention system.

• Snip-Off breakaway support tabs, keeps the separated segments stable while printing.

• No glue required. Just an elastic & cut off the support tabs.

Printing

Recommended material: Polypropylene (PP)

Other rigid materials may not flex sufficiently and could crack during installation or removal. PLA too brittle, PETG too stiff, PCTG & ASA snapped, TPU too soft. PP is just perfect, very like the original OEM that used TPE. Lay down PP (packing tape) on your print-sheet. I paused after the first layer and put some rare earth magnets on the tape to keep it secured down as PP loves to lift. Please see the profile settings for PP listed here:

Vent was closed. Door was taped (except the very bottom) and chamber fan was on 1% to remove fumes.
I added organic support for the centre dome and I added a large brim to try and reduce any lifting. I was well happy with the results!

PP, 100% infill, brim separation gap to 0mm, 20m wide, and my usual 10mm/s first layer speeds.