I've been looking for plans for a powered 3-roll bender to no avail and decided to try to build one myself. The capacity is a little more limited then I wanted, but it was economical and easy to build out of a Proline pedestal ring and band roller which you can get on Ebay for about $90. All together I think I spent about $250, but all of the parts were new. I used a 250volt AC geared motor from Supluscenter.com($80). It is 1/6HP and is continuous use with 900in/lb of torque(intermittent with 1100in/lbs) and has 8.4RPM. The speed of the motor with the torque needed is the tough part. I wanted the roller on the bender to spin at about 15RPM which translates roughly to about 2.5in of material per second. In order for me to achieve that with this motor I had to put a bigger pulley on the motor and a smaller pulley on the roller. I used a belt and pulley system instead of chain and sprocket. The belts will slip if the pressure is too tight on the rolls where as the chain stopped the motor. This might be solved by using a motor with more torque(which I would probably try to find next time 1500in/lb at least). I had to reinstall the old handle so that when the resistance on the rolls was too much I could assist it, but it usually took very little effort. I used a great website to figure out the pulleys needed to convert the RPM from the motor to the RPM I needed on the rolls. Had I had more RPMs on the motor I probably could have gotten a little more torque with gearing. The capacity of the ring roller is 3/8" x 2" flat bar max. I'm not sure if my motor will handle that or not, but I'm sure I'll find out here in the near future. I've never tried tubing but I'm not sure the roller has the clearance for anything over 3/4" thick.