Recently we had a job made from 8" x 1.6" barstock finished to OAL 1.5" x 2.98"ID , 8"x1" OD (flange), and 3.438" x .5" OD (hub) , the 8" od didn't quite cleanup all around.
In the first machine the part was drilled, faced, and the ID was cut to size, held in softjaws
In the 2nd machine the part was held on an ID collet faced to length, and both 3.348" & 8" ODs were cut.
In the 3rd machine the part was again held on an id collet 4 holes were drilled, 3 holes tapped, and a 3/16 slot was milled in the 8" x 1" portion of the part. from the od to approx. a 6" dia.
I am confident after several samples and many measurements the ID the size was not affected from the id holding,
After machining on the mill(3rd step) the ID shrunk .002", which is over our allowed tolerance. The 3.438" od also shrunk but was within tolerance.
The location of the shrinkage was directly in line with the slot and 1 of the 4 drilled holes
I think it is from slotting the part and am curious if anyone has run into similar situations with this type of material or any other, or was this a fluke.
An thoughts on this would be appreciated.

CHEERS