Re: [CAD_CAM_EDM_DRO] Accuracy

Jason Cox wrote:

> Hello,
>
> Just wondering what exactly determines the final accuracy of a cnc, is it a combination of the leadscrews and driving motors?

Everything! The accuracy of the alignment of the ways with each other, and the spindle
with the XY plane. The stiffness of the ways, leadscrews, column and head, etc. are also
important. Small errors in the pitch of the leadscrews can be compensated in software.
Backlash of the leadscrews (and anything else that has looseness) will affect accuracy.
Most of these errors may mask the small errors in the leadscrew and stepper motors.

> Also can a gecko servo drive be used with a glass scale instead of a rotary encoder and would this give greater accuracy?

Yes, in general. Unsually, the lower accuracy glass scales made for cheap DRO systems
are a little coarse (.0005" or .01mm per count) for CNC motion control, but they should
work. If your screws have a fair amount of pitch error, but no backlash, then the linear
encoder would improve accuracy. It will also cost more, unless you already have them.
If the screws have much backlash, it will be a disaster, with the motors constantly
hunting across the backlash distance.

Jon