Re: [CAD_CAM_EDM_DRO] Re: measuring scales and thermal compensation

In a message dated 3/17/00 11:34:17 PM Hawaiian Standard Time,
Ian@... writes:

<< The problem here is that if the workroom isn't
at 20C - and mine, for instance, can often be 10 or less when I start
working in it - then the machine itself will have contracted more than the
glass scale. So, if you work to the scale, the part will come out big. >>

I think this needs to be qualified. If the part material has shrunken from
cold temps and you cut it with an accurate scale, then when the part is
brought up to a higher temperature, then it will have grown bigger than
intended. Even if the machine table has gotten cold and "shrunk", as long as
the feed back scale is accurate, and the part is normal temp, the part will
still come out to size. The big problem I saw was when the scale was anchored
to the opposite end of the table from the ballscrews anchor bearings. In this
case, you get all kinds of errors from cold to hot. Both the table and
ballscrew change length to really mess up the results.

Observations.

Peter
THRD, Inc.