Re: [CAD_CAM_EDM_DRO] EMC homing

Marshall Pharoah wrote:

> From: "Marshall Pharoah" <m_pharoah@...>
>
> I have a few questions regarding the home switches...
>
> Are these used to provide a precise home location from which you can
> then locate the
> target?
>
> If so, how do you achieve that precision, with optical transceivers?
> It doesn't seem as though
> mechanical switches would switch at the same point each time.

If you have encoders with an 'index' channel, then the home switches
just get
you close to the index pulse, and the program searches for the index
pulse
from there. The index pulse can be gated with the 'A' channel of the
encoder
to get you down to a single encoder count, or left as is, which will
usually
get you within 2 encoder counts or so. If you want to do this without
encoders,
you could put a beam-break type optical sensor at the motor shaft, and
have
a disc with a narrow slit mounted on the shaft. That would qualify the
switch
to within a couple steps.

Jon