I do a lot of work with 1/16 inch thick 2-color acrylic (the IPI / inventables stuff)
Invariably I’ll have this problem where my test pieces come out perfect, but when I try and to a production run that takes up even half of a 8x12 sheet, the later operations and cuts are shifted by fractions of a mm. Enough to make a significant fraction of the run fail my QC and kill my yield.
Initially I thought this was due to stacking tolerance issue with the GF where over time enough small errors built up to cause the drift, however I have come to the conclusion that it is caused by thermal expansion of the thin acrylic during long engraves and multiple cut operations.
To solve this I’ve given up on just cutting the sheet as a whole. I now precut the sheet into slightly oversize squares that fit into a draftboard jig that holds each one, keeping any thermal expansion effects limited to each single piece instead of having them stack across the entire sheet.
The scored lines are registration marks allowing me to line the jig up exactly. All I have to do is import my files into the jig file and then horizontally and vertically align with a particular square to locate it in the pattern.