[CAD_CAM_EDM_DRO] Re: Measuring backlash with a ohm meter

At 7:25 PM +0000 10/23/04, vavaroutsos wrote:

>Ron, I may have mis-understood what Chuck was saying, but I think he
>is measuring the electrical resistance from the work to the spindle,
>not the resistance to movement on the axis. This would require that
>the work be electrically isolated from the mill or the probe be
>electrically isolated. Things may have worked ok in Chucks case due
>to the construcion of the mill not providing much electrical
>conductivity from the spindle to the table, but I don't think this is
>a valid assumption for all mills.

Yes, I was speaking of the resistance from the work table (and the
work) to the spindle. The idea being that the electrical path from
the table to the base, then to the spindle through the mount bearings
(i.e. through the many joints) is going to be higher resistance than
the direct path when the bit touches the the work surface. That
change in resistance, though it might be small could be noticed by
the software and acted upon.

I would be interested to know what the spindle to table resistance is
on a bigger machine.

The reason I tried this is because I am just learning to use a dial
indicator and wanted another check. :) -Chuck-