I've ran some pretty large machines. For the most part, on normal tolerances (+/-.005 and up), it really wasn't an issue. There was only 1 instance that I can remember thermal expansion being a problem. We had to drill some holes in some wingskins several hundered inches long, and they had a tight true position tolerance and couldn't seem to get them right. After looking into possible problems with programming, and machine malfunctions, it was decided the problem was due to the temperature change caused by the vacuum fixture being used.
The vacuum made the part cooler than it was supposed to be. So each time the holes were to be drilled, the temp of the part was taken, and it was entered into a formula within the program that adjusted the position of the holes.
Dustin B.
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I hear and I forget.
I see and I remember.
I do and I understand.