Re: chinese dro scales

I have cut down the bar on a Harbor Freight 6" digital caliper with
success. These calipers are of the same construction as used in the
scales that you mention.

The stainless steel bar has a recess for an adhesive backed, marked
and calibrated tape. Behind the marked tape is a precisely etched
copper layer that has a squarewave shaped etched gap about .010"
wide. There is no voltage on the copper tape. The linear capacitive
detector in the display unit senses the edges of these gaps and
appears to use the gaps to resyncronize (re-frame) the digital
counter periodically to maintain the accuracy.

The stainless steel is very hard. A Dremel rotary tool with a cut
off disk (the brown kind with the cloth weave look) is needed to cut
the stuff. Keep the bar cool with a damp rag while cutting it.
Water will not hurt it unless you let it get into the display unit.

Richard


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "malehawkee" <malehawk@s...>
wrote:

> I am fitting a set of chinese (dro) scales to my mill. Now I have
> not seen anyone cut the scales to lenth to suit the application.

My

> question is: is the scale part of the curcuit for the dro, and if

the

> lenth is altered will the scale be useless? Nick