I have seen many builds on HBT where guys have motorized the Barley Crusher....myself included. I can't speak to the longevity of my mill, as I just completed building it and have only used it for 3 batches thus far, but it's holding up fine. The mill is suprizingly study, so I was very comfortable motorizing it. I used a 1/3 hp 1725 rpm motor with a 1 1/2" pulley on the motor shaft and a 12" pulley on the mill (had to get a 1/2" to 3/8" reducing bushing). This got my rpms down to a working range (215 rpm's) and with the exception of fine tuning my gapping I have had not problems with the belts slipping, adverse torsional stress on the mill shaft, etc. Finding a 1/3 or 1/2 hp motor should be easy. Figuring out how to reduce the rpms is the next challange. Gear boxes are way to rich for my blood, so I went with the pulley route. I have clearance issues with the 12" pulley and the 7 lb. hopper, so I built a new hopper. Here's my build if interested.
http://www.homebrewtalk.com/f51/hoppos-rustic-motorized-grain-mill-cabinet-grain-storage-bin-355241/
Good luck!
