I am an industrial sewing machine power stand user, and have 4 industrial power stands in service right now. But, they’re all clutch motor powered, so I don’t have a Servo motor to help you with your comparison. My clutch motor speeds range from 3470 RPM down to 1725 RPM that has an 8:2 step-down speed reducer (step pulley) on it. The 3470 actually feathers better than you’d think, although still fairly fast, and still has blazing speed when wanted; one of the 1725s feathers very well; a second 1725 doesn’t feather very well at all (possibly because it hasn’t been used much, and I have a 10:2 SR to put on it next spring); and we feathered the 1725 that now has the 8:2 SR on it for several years before putting the SR on it. Boy, did the SR make it a pleasure to stitch slow! We never had a runaway with it, but we always feared that we would. Actually, learning how to feather a clutch motor used to be a desirable feat, but not so much anymore.
I have two projects in the works with clutch motors involved. One will be an old Singer 1725 RPM clutch motor that I’ve never ran before that I’m going to see if I can put it back into service on my convertible electric/treadle stand to power a Singer 96-40, and the other will be an old Atlas clutch with a GE 1725 RPM motor on it that I’m going to try to power a Singer 95-40 with. I had a Singer 31-15 pass through my hands that had an old Atlas clutch on it (you can use about any motor on one) that was surprisingly easy to feather for slow speed. I was impressed! After researching, I discovered that back in the old days, mechanics would put grease on the cork clutch linings to get more slippage and better slow-speed response. Replacement cork linings were readily available, but when you think about it, grease is meant to reduce wear on matching surfaces, so I don’t know that the cork wore any worse with the grease on it than without. I know that I want to experiment with one, and hope to do so in the next few months. These last two projects are an attempt to restore usage to power stands using the old original motors and clutches to restore the units back to the original configuration.
If I want ultra-slow, and since I don’t have a Servo motor, I resort to one of my industrial treadle stands that will place one stitch at about any interval of time that I choose.....sometimes one today, ........and another one next week............or next month......
CD in Oklahoma