Miniature belt reduction

[jaybee]

I'm working on something not automotive related. I'm trying to drive a hand cranked knitting machine with a 1/4" belt and a sewing machine motor. My first mock up is done, and it makes the knitting machine run too fast. Not sure what to do here. My ideal would be a pair of pulleys on a shaft, or a step cone pulley. Ideally I'm looking for about a 4:1 gear reduction. I've looked at McMaster Carr and Amazon but can't find anything to do the job. Any ideas on where to go?

[enjenjo]

Did you look at these? https://www.amazon.com/Mechanical-Timing-Pulleys/b?ie=UTF8&node=16411441

[jaybee]

Thanks, Frank, I didn't know just what search term to use to find something that would work. If I replace the V belt pulley on the motor with a small timing belt pulley, build a jackshaft arrangement with the big timing belt pully and the original motor pulley on a small pillow block it should work. With 3:1 reduction on the first stage and 4:1 on the second stage it reduces a 1900 max motor speed to about 160 at the knitting machine. Pedal it back to about 1/3 and it should be very workable.

My first mock up doesn't work for two reasons. First, 475rpm is WAY too much for a hand cranked device. Second, while sewing machine motors throttle they only go just so slow. At a 4:1 reduction it doesn't give enough torque at the very slowest speed the motor will run and after a test of a few brief minutes the motor was starting to smell warm.

Better yet, I see there's a 20/80 version of these timing belt pulleys, which pushes the max speed all the way to 120. I know we can pull it back to a workable speed from there.

[Bruce Dorsi]

How about : https://www.amazon.com/Variable-Single-Phase-Adjustable-Reduction-Controller/dp/B09JZBSV78?th=1

[jaybee]

Thanks Bruce, that's a sweet little unit.