Originally Posted by
Jim Dawson
Just to put this in perspective, first concider that 400 Nm is about the torque output of a mid-sized auto engine, and that number seems pretty reasonable for a direct drive tube bender. That would be a huge servo motor.
But not very practical in this application. First you don't need to turn the tube bender at 2500 RPM, more like maybe 2 RPM. A much smaller servo motor and a massive gear reduction would be practical. Maybe a gear reduction of about 1000:1. The gearbox is going to be more expensive than the servo motor. The motor torque is multiplied by the gear ratio. I would be looking for a planetary gearbox in the 500 to 1000 : 1 range, then choose a servo motor to match.