Originally Posted by
A_Camera
...but isn't the TQ circuit THE problem? I mean, yes it works but isn't it limiting torque far too fast? Without the circuit holding torque is kept at 100% and as far as I understand, the only negative effects of that is more motor heat. As long as the current settings are right, that should not cause a problem, but if the holding torque is low and you can fairly easily turn one axis by hand then the negative effects of that can be drifting of that axis during milling, especially milling something a bit harder like aluminum. Am I wrong?
There is a similar circuit in my 3 axis blue card based on TB6560, and I have just removed that circuit for that reason. The limiting circuit works, the motors are cool during hold but the torque is limited so I was afraid that when I start milling that will be a problem. Another thing, the circuit caused a few extra steps due to quite severe HF noise generation on the step signal. Once the circuit was removed the noise disappeared and everything looks fine on the oscilloscope. BTW, have you checked on an oscilloscope (without HF noise rejection set) how the step signals look like on your cards?
Anyway, thanks for tracing the card and making the circuit diagram.