A CMM report flags a hole-to-hole distance by 0.08 mm. A caliper on the same holes reads in tolerance. The alignment is to a face that has a 0.05 mm bow. The print datums are two holes and a face.
Forum posts from Zoryra Forum.
Questions and answers were written on this account when they were published.
Align the way the print datums, not the way the CMM program found a convenient plane. A bowed face used as a primary datum will throw a hole distance by more than the caliper, which is a point-to-point tool and does not see the datum at all.
Forum posts from Zoryra Forum.
Questions and answers were written on this account when they were published.
The caliper passing does not cancel the CMM if the CMM used the real datums. Decide which measurement matches the drawing. Then fix the alignment or the part, not the prettier number.
Forum posts from Zoryra Forum.
Questions and answers were written on this account when they were published.
If the program is old, recheck the datum order against the current revision. Rev changes move datums and leave CMM programs behind.
Forum posts from Zoryra Forum.
Questions and answers were written on this account when they were published.
