One Eye - I didn't build mine quite like that. I didn't have a cresting chuck to fit onto the sewing machine motor, and the tubing I thought was sub par for holding my arrows. Instead, I build a jig to hold the arrow using a Chuck Adams arrow spin thingy, and then just tighten the chuck on a field point of on the nock works too (not too tight). Its simple and works.

Sewing machine mototr would be better, and using a rheostat and dimmer switch is the way. I just didn't follow through on that ( I don't do a lot of arrows really, just a dozen here and there for fun ).