Hi
The other day i say a device that was attached to a lathe that gave a
digital measurement from the tool (ie the position of the tool on the bed)
to another point. *maybe the chuck, but this box had a zero button.
it used a sensor that was waterproof, it was parallel to the bed, and had a
male and female V section that slid over the other.  this unit had imperial
and metric modes.

my question to you all is, how would you make something like this ?
how do you determine a distance to a resolution of a maximum of 1/1000 of an
inch  that is waterproof and can live in an environment that is noisy, has
oil/ water, metal shavings, vibration etc.

regards


Pete