This labor of love and money was also for Cory. Basically, there are these two weird Chinese merchandise stands that get sold at places like Spencer’s, and Cory was like, make one go a few percent slower than the other one. I think originally he was thinking stepper motors or something which is why I got involved, but it was a lot more low-level (in a wedge-screw-pulley-inclined-plane kind of way and not so much an assembly language kind of way) than that.
Inside one of these things is a reversible synchronous AC motor with a toothed belt linkage. A quick test with the Variac proved that, yes, their speed was independent of input voltage. Turned out the easiest way to get the speed differential was to pull the original transmission parts and replace them with XL drive pulleys and belts. The OG stands use a 3mm (I think) Chinese pitch system which is kinda hard to find around these parts. McMaster saved the day as usual but now I get my goodies from my pulley people at B&B Manufacturing who have likely forgotten more about power transmission than I ever hope to know. One thing about McMaster, they aren’t shy about leaving other peoples’ labels on their parts :-)
Doing this meant a lot of cutting and tapping, which is fun for me because I rarely get to do it professionally. To wit:
I had to drill out the pulleys (they’re made for 0.250″ shafts and the shafts in the stands are 7mm) and got all noided about leaving tap magic on them because I was worried about the belts not liking it. This was part of the washing/drying process and won me zero points with my housemates.