Re: [CAD_CAM_EDM_DRO] gauge blocks was Re: Rolled Ballscrews

Smoke wrote:

> I wonder if you all aren't worrying to much about temperature changes.
>
> Lets, see...if the machine and the measuring tools are kept in the shop
> together long enough for the temperatures to stabilize, any changes in
> length due to temperature changes will be virtually undetectable using
> "standard shop measuring tools.
>
> However, if your machine is all aluminum and the tools are steel, then you
> "might" have a problem. A 20 degree temperature change will cause a length
> variation of .0029" over 12" in aluminum and only .0015" in steel. The
> difference of .0014 would then be measurable.

For any hope of achieving high precision in Aluminum, especially, you have
to watch workpiece heating by the cutting action. many times I have had
to stop work when I got close to final size on something critical and let
the part cool. Especially on my lathe, which does not have flood coolant.
I just leve the spindle turning at a fairly high speed, and the fan action
of the chuck jaws sucks air over the part. it sometimes takes a half
hour to cool, after turning off a lot of material. Sometimes I've seen
relatively
small parts (1 - 1.5" diameter) shrink .010" during cooling off!

Jon