I accidentally submitted this as a "Ticket" yesterday, but thought it might be good community knowledge.
Regarding the "Top" and
"Bottom" Reference Lengths; do they refer to the "base" of
a measured feature? I have a part right now with a projected tolerance of
.200" on the OD of this part. One of the features, CMM-M sees the base towards
the outside of the feature, the other feature it looks like CMM-M is seeing the
base at the bottom(inside) of the feature. I'm wondering how this will affect
the number I put in the Reference Length.
Assume you have a cylinder with a nominal length of 20mm (where the base is or direction is doesn't matter). You INSPECT 15mm of it.
If you specify a length of 20, it will take the error of 15mm / 15 (ie: per unit) * 20. If you specify 50mm it would simply be the per unit (the 15/15) * 50.
If you specify a cylinder with a base at -100 with a length of 50, but measure an actual cylinder (in space?) at -30 and -10 (20mm worth - but beyond the definition) it will still give you the same answer.