Re: [CAD_CAM_EDM_DRO] Emc stepper setup

The Driver25 board looks to be based on the A3977.

The A3977, like pretty much all the Allegro chipsets, are generally
unsuitable for CNC. They cannot resolve microsteps (barely even
fullsteps) when the high driving voltages needed for CNC speed are
employed, due to the large minimum ON-time established by Tblank on
those chips.

Danny

On 12/17/2010 11:37 PM, Brian wrote:
> Hi all,
>
> I am slowly getting to my first cut, thanks to help received here recently - thanks guys! I am struggling to sort out an issue with stepper motors. In the setup and tuning, one stepper seems to come up short of the instructed distance in the test. I have all the boards set on 1/4 step, so as I understand it, this setting in emc must be 4.0? And 8.0 for 1/8 stepping? This problem axis moves half of what it should. All the boards are set exactly the same, so could it be a faulty board. I can swap them about and see, but I just want to know if maybe i'm doing something dumb before I dive into the wiring. Also, the non-faulty z-axis sounds smooth and sweet, the other two have a raspy sound, and it is definitely not a mechanical thing. Could it just be resonance from the way I have them mounted? The driver boards are Diycnc "driver 25" boards. (diycnc.co.uk), the steppers Keling 270 oz/in.
>
> Many thanks, Brian
>
>
>
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