Re: [CAD_CAM_EDM_DRO] Flat as a (very precise) pancake...

Tom,

I think you probably need to bear in mind that flat stock is only flat so
long as you do nothing to it. As soon as you start to machine it at all you
will start to relieve stresses and the material will warp. I just made a
table for my milling machine out of 12"x6"x1" flat stock and cut 3 tee slots
in it. I then sent it for surface grinding and they had to take 30 thou off
each side before it came back to flat! The other thing you have to allow for
is that such grinding has to be done carefully and knowledgeably as the
magnetic chuck on the surface grinder will pull the metal flat while its on
and the metal will then spring back when the chuck is released. This was
happening even with my 1" thick block and so the grinding had to be done a
bit at a time on each side, continually turning the work over to bring it to
flat with the minimum of metal removal.

Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk

----- Original Message -----
From: "Tom Murray" <thomasm923@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: 27 March 2001 05:43
Subject: [CAD_CAM_EDM_DRO] Flat as a (very precise) pancake...


> Is it possible to get Precision Ground Flat Stock that is more
> precise than the usual off-the-shelf stuff?
> I'm talking about parallelism somewhere in the neighborhood of +/-
> 0.0005" per foot in width and thickness.