Shower Temperature Knob

Here's a replacement Shower Temperature Knob for a 24 tooth 9.6mm spline mixer valve.

The original chrome plated plastic one snapped off internally around the receiving female socket for the spline.

With no replacement that I could find so far; I decided to create this temporary one in the meantime. It's based loosely on the original part & printed in PLA with 100% infill at a 0.28mm layer height on the Ender 3.

The first version was a bit too tight to push onto the spline, so I used a mini pencil blow torch to blow 5 seconds of heat through the back of the knob spline area to soften the teeth a little just before pushing the knob home onto the spline. This created as perfect a fit as I could have hoped for. I left it 2 minutes to cool down, removed it, then replaced it and secured it with the original center screw. This version has a touch more clearance but would likely also benefit from the same approach if a bit too tight.

The printed part is now in daily use & no longer considered a temporary fix ;-) I just need to learn how to apply a chrome finish to plastic parts...

Hopefully this helps someone else.