Turning Down a Motor Shaft

[Tony Wells]

The second shop I worked in did all the machine work for a nearby electric motor shop, so we got a lot of metalizing and shaft repair /replacement. If you wanted, for any reason, to maintain the original shaft, they are pressed in and can be removed and replaced with a newly made shaft of whatever size you want. Otherwise, a 4 jaw with pads, and a good bearing center is sufficient to turn it down. Watch that you don't reduce the seal area if the motor has a live seal on the shaft, and be sure to leave a 1/32" minimum corner radius where you shoulder out. And you may have to recut the keyway, or at least need to make a non-standard key.

If possible, boring the sheave/pulley would be preferable.