On Sat, 1 Mar 2008 07:08:13 -0500, the renowned "Backlash"
wrote:


"DoN. Nichols" wrote in message
...
Thermal expansion is a killer when you are aiming for precision.
If you have flood coolant, you will have less problem with this.
Otherwise, the only choice is letting it cool for a *long* time between
rough cut and finish cut.

Good Luck,
DoN.

--


Since I have a one man shop at work, I have a compressed air hose at the
headstock end of my work lathe, and use a high volume/low pressure nozzle to
cool the part down before taking measurements. Cool part, go get a drink of
water, come back and measure. If I am more pressed for time, I will use a
can of high flash-off spray degreaser to chill the part down faster, waiting
after each shot, and checking for temp on the part with the back of my hand,
before measuring. A non-contact laser thermometer can also be used.

I would think that would be very difficult--- at least on a specular
surface like freshly machined metal. It will mostly be measuring the
reflection of whatever else it sees. Maybe if you could point the IR
into a cavity on the part. But I'd use a ribbon surface thermocouple.

Another
trick that the air is good for is to mount a flex hose blowing low pressure
regulated air through the headstock bore to keep chips from tumbling around
the end of a boring bar on a through bore, potentially deflecting it in use.
This automatically keeps the part cooler while machining.

RJ



Best regards,
Spehro Pefhany
--
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