On Mon, 07 Jan 2008 22:27:10 +0000, Dave wrote:

Never having seen one, another thought is, how do you calibrate one?

Presumably the same as you'd check a bubble one set it on an adjustable
surface take a reading, rotate 180 deg, take a reading adjust surface so
that read is half way to the previous one, rotate again, repeat until the
reading doesn't change between rotations. If you can't get the reading not
to change between rotations no matter what you do with the surface it
means the sensor is not correctly aligned to the base.

--
Cheers
Dave. pam is missing e-mail