3D modelling replacement knobs for back massager

small wooden knob

small wooden knob

There’s this fantastic device we have at home that I’m fairly sure is for giving back rubs, or maybe massages in general, like on your legs or something. I’ve tried it a few times but mostly the kids play with it. However it bothers me that there’s holes in it where the little knobs are supposed to be, so it doesn’t roll properly. I think the kids pulled them out, but maybe they were just never glued in properly.

holes from missing knobs in massager

holes from missing knobs in massager

Anyway, I doubt I could go in a shop and say “please give me tiny wooden knobs to this size” so I decided to attempt to print some. I’ve done some basic 3D modelling work before so with a bit of work and the right measurements, this should be doable, and it’s an interesting shape.

sketch with measurements for wooden knobs

sketch with measurements for wooden knobs

Here’s a hand-drawn sketch I did quickly after measuring the wooden knob with a pair of callipers. It immediately became apparent that this was not going to be as simple as I thought because shaft part isn’t straight, but more like a chopped-off cone, and the head part isn’t round on every axis, it’s an ellipsoid. I Googled that word 😅 just to write it in this blog post, it’s the 3D version of an oval. Continue reading