Measuring backlash with a ohm meter

I just tried something and it seemed to work well, but since I am a
newbie, I wonted to pass it by the list to see if it might be useful
to others.

I wanted to measure the backlash on my Sherline, so I attached an Ohm
Meter to my mill. One terminal to the bed, and the other to the
spindle. It read a resistance of about 2k ohm. Then I lowered Z till
a bit touched the surface of the milling plate and the resistance
went to zero. Then zeroed Z and micro-stepped back up till the
resistance went back to 2k ohm. Z showed .0012. To test, I lowered to
zero again and as Z hit zero, the resistance went back down.

Using this information, it seems that you could devise an
edge-finding routine for any metallic object that would position the
bit exactly in the X, Y, and Z planes with respect to the object to
be milled.

Has this been tried before? -Chuck-