Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[Zeeflyboy]

Typical stepper is 200 steps per revolution. You have 5mm screws, so you move 0.025 per step (5/200).

Microstepping doesn’t really count, so the fact you have eg 320 per unit (can’t remember exactly what the stock setup is) isn’t really what you’re looking at, though you could argue with little to no load it won’t be far off.

That said, I can move mine in 0.01mm steps on the jogging button but I have 1.2 degree steppers (so 0.017mm per full step) with built in encoders and microstepping gives 800 per unit.

Just edit your jog values so that one of them is 0.01mm and it’ll do it’s best to match. If it is 320/unit then you have a base value of 0.003125 so any movement will be a multiple of that - that means the closest movement to 0.01mm you could theoretically get is 0.009375 which is why the value in the readout looks a bit odd - it’s physically impossible for it to move to any value that isn’t a multiple of 0.003125. Again though microstepping is not really reliable regarding accuracy so your “real” resolution is 0.025 as limited by the motor steps per degree and the pitch of the ball screw.

Btw I would try to use the least amount of travel on the dial indicator - those type can have a fair bit of spring push and you may be deflecting the probe rod slightly. No guarantee that the deflection is equal all the way around.

Do you actually need to jog into the dial for this? I just spin the guage zero so that it sits in the middle of the values for either side and then adjust probe until it reaches close to zero, then move to the next set of screws and repeat, then go back to the first as it may have moved slightly. That will normally get runout to less than 0.01mm for me. Definitely a bit of a knack to it but it only takes me a few minutes now.

Oh and finally have you tried calibrating the machine? Mine wasn’t exactly wonderfully accurate out of the box. I think mach3 even has a screw calibration wizard that saves you doing the maths.