Good Morning! I have this part (shown below) that calls out a slot as the tertiary datum and I am having trouble trying to get the true position to show the MMC to .0002 for the callout for -D-. I am measuring it by taking 1 hit on each side of the slot and making a midpoint between the two. I am also not able to add the MMC modifier to either of the .100 TP or Perpendicular callout or the .125 TP callout. Is there a certain way to do this?
Is your slot stepped? I dont understand how there's [TP][0.0002(M)][A][B(M)] to the un-dimensioned extension line AND the composite [TP][0.000(M)][A][B(M)][C(M)]
also neither of those true position have a diameter callout in them, so the tolerance zone of position is linear/square, not round.
Re: how to measure the left callout [TP][0.0002(M)][A][B(M)]
you need to measure the slot walls as planes, then construct a midplane of the two walls of the slot. as crazy as this sounds, if that slot is not perpendicular to A, or rotated so it is dead-nuts concentric with B axis by 0.0002" (at MMC) relative to [A] and [B (at MMB)], it would fail.
This is effectively redundant to the right top TP FCF, with exception that somehow the right FCF is controlling it tighter. That's why i suspect there are two features which are in that slot... there's no logic behind the redundant callouts otherwise.
