A 3D Printed Dial

I had a broken dial. I also have a 3D printer, so rather than epoxy the heck out of the old one, I designed and printed a replacement. One finished 3D printed part was produced with just a few hours of work.

My pool has a salt cell that uses electrolysis to convert salt in the water into chlorine. You manually set the level from 10% to 100% generation but I usually leave it alone at it’s maximum setting.

That dial literally has one job and it broke. It was flush with the panel so rotating it meant scrolling the right exposed side. Built out of cheap injected plastic though it did last for 7 years.

In Fusion 360 I started with a stub to make sure I sized the knob holder correctly and ended up with a knurled dial that protrudes from the machine. My process isn’t very good and I learn through “what’s that feature do?” For example, the knurling was put on my making a sketch, extruding and cutting it out of the dial then creating a circular pattern out of that 120 times.

The effect came out great. My first pass has knurling that was too shallow (0.5 mm). Until I printed it out I couldn’t see that I had made a mistake. Once I saw it I went in the designs time line, deleted the sketch (which also deleted the pattern) and re-did it again. The new knurling rocks.

The last iteration was missing something. I put on the face a cutout to show that turning it clockwise means more, counter clockwise means less. The original dial had that printed on the face but my cutout is more prominent. It also meant I got to try something cool on my design.

I started with PLA but when I got what I wanted I printed it in ABS plastic. Here’s a photo of the iterations.

Yes, I could have fixed the old dial with some epoxy. That would have molded the broken part nicely. But it’s not often I get to use one of my toys in a real world way like this. 2 days of on/off fiddling got me the part I really wanted.