Yes the sewing michine motor might be hard to control with a clutch. It is also a really fast motor at around 3400 rpm. I have a couple of comercial sewing michines and it is easy for them to really get going even on a sewing michine. However, even if I set the extractor up with what I have, changing just the motor should not be that hard. I am sure I will run on to a junk treadmill one of these days. I sold my wifes for $50/75 (can't remember for sure). I have a treadmill motor on my jointer now. Tread mills and weight sets seem to go unused. I made a sawmill out of a weight station, trailer hubs a garden tiller that had the tranny out.
I believe I have a shaft for the extractor. It came of on old back massager. Funny looking thing with dowls that you leaned up against to get your massage. What I am trying to think through is how to be able to have enough support but yet be able to load the frames from the top with out having to take anything apart. I looked at two bicycle rims as an alturnative but they were too wide to fit in a 50 gal plastic barrel.
My stuff will probly be a little more rickety then what you build but I expect it to work. If I ever get the extractor and my bees live long enough to give honey, I will then need a labeler
My goal as always is to not buy anything while I make stuff.