Just a couple things that might help as you get up and running: #1 Stepper motors need an acceleration profile if you are moving them at high speeds. They have inertia, and will miss steps if you do not profile them. This can be easy if you are running closed loop since you can easily detect missed steps (command versus actual count). #2 Driving excessive current will not give you more torque, it will do the opposite. Core will saturate, and all kind of nasty things happen. One of the major ones is that the resonances of the motor will change. You will find various stepping rates where the thing just won't step. #3 Resonances can also come from the mechanics. For high speed moves it is common to see a fluid damper on the motor shaft. Mechanically balances out the whole system dynamically and can correct some resonance issues. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads