Newb question about microstepping. LMS 3990 mill. Mach4

I only need to have accuracy down to Half a Thou. .0005

Doing some math - It looks like if I setup 1/2 microstepping with my particular setup - That will exactly equal this goal.

So my question is - should I choose 1/2 mcrostepping, or is there some engineering juju that I do not know about using higher microstepping rates, that would be a better choice? i.e. - what microstepping rate do you think I should choose for my setup? (and please explain why you recommend that - I am hoping to learn something).

The math I used:

https://www.cnczone.com/forums/attac...d=421278&stc=1

The less steps the computer has to generate the better imo.
Theoretical resolution is over used.



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In general, I try and stay away from relying on microstepping to achieve the resolution you want. Your holding torque decreases significantly when you microstep and if your machining forces overcome your motors torque it's going to "jump" to the nearest full step anyways. My personal suggestion would be to use a belt drive to gear it down.

I agree in part, but "theoretical accuracy" is not the biggest reason to use microstepping. Improved low speed smoothness, and quieter operation are also benefits. That improved smoothness actually helps in terms of the maximum torque you can actually get out of the motor. I don't recall the exact numbers but I played with this on my mill and with 16x microstepping I could rapid faster than at no or 1/2 microstepping. It is also noticeably smoother.

As far as accuracy goes, 1/2 microstepping is EXACTLY between full steps. Beyond that it isn't perfect, but a 1/4 step is closer to a exactly 1/4 step than either a 1/2 step or a full step, and a 1/8 step is closer to exactly 1/8 of a step than a full or 1/2 step. So you do indeed gain accuracy.

With the above there is a point of diminishing returns. Where is that point? I'd say around 8x to 16x microstepping. I have mine set to 16x. If you controller can feed pulses fast enough then I would put it in this range. Its funny that Gecko drives are locked at 10x at low speed but go to full stepping at high speed.