Plumbo – A simple way to measure horizontal rotation

Over the years I’ve had issues with large parts and finding easy ways to lay them out angularly, especially on the ram EDM. During this time I’ve kind of tinkered in my head with an idea whereby you have a level of sorts stuck to the part and you simply rotate it and have a direct reading of rotation applied to the part. I have tried those digital levels but accelerometers don’t have the precision required to get within a few thou over, say 6 inches.

The prototype device as it is right now

It’s obviously very rough and uses a cheap Chinese 2000ppr encoder but it’s good enough for .045 degree increments. I would trust this thing for some larger layout and alignment work. That said, I have a nice US digital encoder on the way with 10000cpr (40000 ticks all the way around) so a resolution of .009 degrees. Some issues I’m having is with the mass. If the mass is too small it won’t overcome the friction of the bearings completely and if the mass is too large it swings for a long time making it a hassle to allow it to settle. I’d like to find a solution whereby I can add friction without adding stiction. Frankly the whole thing needs a good concept redevelopment but I believe it’ll be a handy tool in niche situations.

I’ll keep this updated as I go along.