Reply To: Z lock



From my understanding when it comes to torque and microstepping it’s torque AT that resolution. Meaning the motor will start to lose some of it’s microsteppings if too much force is required to move, but as long as you aren’t overcoming the motors actual torque ability it will ‘catch up’ at the next full step. I’m no expert on it, but here’s how I understand it. Picture the magnets pulling the shaft around inside the stepper, now imagine with microstepping that power is being changed so that the shaft is finding itself attracted between multiple magnets just enough to hold it in a specific area in between the two of them (there’s why you have less torque at that resolution – one magnetic field is ‘fighting’ another one and that’s what is holding the shaft where it’s at) The more you do that (1/8, 1/16, 1/32) the less the motor can hold in a specific position. Now, when it gets to the next full step though it’s going to deactivate those competing forces since it’s no longer trying to hold between two full steps, and the shaft will jump to the next step because it should be at full torque there. The shaft should ‘catch up’ in other words – it won’t always be where it should be if the forces are overpowering the microstepping, but you aren’t going to miss extra steps because of missing torque (when it gets to the next full step it’s going to jerk the shaft to the next full step where it should be).

I just changed the Z axis on mine because it was hitting the Arduino Mega limit. I don’t think changing it on X/Y would make those axis go faster (at least not when milling since you aren’t going to be pushing those axis to 200mm/s when milling).

In the micromo article they phrase it as: “The rotor will lag behind the rotating magnetic field until sufficient torque is generated to accommodate the load.” which I take to mean the example above – it’s going to lag behind where it should be if it can’t overcome the load for the microsteps, but then when it hits that next full step the magnetic field will have rotated to a point where it has normal torque and overcomes the load.

In the end though if my Dewalt is being pushed towards something typically it gets deflected more than any .0001 inch difference that is ‘in theory’ the difference between 1/8 and 1/32 stepping (going from ~4000 steps per mm to ~1000 steps per mm) so changing to 1/8 won’t lose anybody any true accuracy either.