Originally Posted by
m_c
Unless you have the KFlop configured to control the servo loop, nearly all analogue servos will run away if you just power them up and enable them. In analogue mode, you are reliant on the controller to monitor the encoder, and adjust the control voltage to maintain position. This will be far more noticeable in torque mode with no load.
Speed mode is usually the most stable operating mode, whereas Torque mode is usually more unstable, however Torque mode bypasses any drive internal speed control/filtering which means the motor should respond quicker, and potentially result in a better tune.
Personally, I'd suggest starting with Speed mode and any default drive settings. Get the KFlop controlling the servo loop to maintain position, ensure limit switches are disabling the servos, and you have a functional physical E-stop button near. Then connect up the motors to the ballscrews, as they need to be loaded for tuning, and start tuning via the step response screen.