[mactec54]

Hi MT - I agree that particular video was not good. But if you look at the Tinyg closer its algorithms are very impressive and can be implemented in other systems as they are open source. The TinyG approach is what I expect best practice open loop motion to be. To go further, closed loop approaches need to be used and these are appearing in 3D printing systems at the cost level that I operate at. The big machine players have proprietary open and closed systems that do amazing things in terms of motion control but they are outside the scope of my machines. Milli my first mill will use servos which is a new world for me.... Peter

In a slight tangent there are a couple of old threads in which flywheels and eccentrics were added to steppers to improve motion (by way of mechanical damping I expect). I can't find if anyone concluded that this was purely a flywheel effect and the eccentrics (small free weights in cavities in the flywheel) where not needed or the eccentrics were functional? Anyone comment on that? Peter

Yes, I remember the weighted wheels that were attached to the stepper motors, it's like everything people try to make things work better, but there are tradeoffs so what appears to work well, may not be as good as it seems, or it would have stuck and been implemented to the stepper motor, or someone would have been manufacturing them as an add on.

There are servos that do not work well, so when you go that route careful what you chose.

Any quality Ac Servo Drive is closing the loop, this does not have anything to do with the control, the control only has to send a signal for it to move, Servo Drives are very sophisticated.