I don't know what this true position on the hole is constraining. Bolt circle diameter or orientation of the hole maybe? Trying to determine if I need to measure the hole as a cylinder. Appreciate the help.
The tolerance zones for the six holes are six cylinders of (initially) Ø0.01 (over the full length of the flange).
These 6 cylinders are fixed in relation to each other (so they are all parallel to one another) and spaced as shown by the basic values on the drawing (60° and on a 4" diameter).
These cylinders, are controlled to Datum A, so they are all also parallel to datum A and, and the centre of the 4" pattern is located on the axis of datum A. This pattern of tolerance zones can rotate freely about datum A to best encompass the measured holes.
The given Ø0.1 tolerance is followed by (m) which means that tolerance (Ø0.01) applies when they're at their Maximum Material Condition - for a hole, it has the maximum amount of material when it's at its smallest size. As each hole deviates away from its smallest size, you gain additional tolerance (and as the tolerance zone is a diametrical value you can simply add the difference in diameter straight on to the 0.01)
As mentioned above (by way of formula) the TP value is double the radial deviation from the nominal centre to the measured centre (because the tolerance zone is diametrical the measured deviation must also be reported in a diametrical way).
The tolerance zones for the six holes are six cylinders of (initially) Ø0.01 (over the full length of the flange).
These 6 cylinders are fixed in relation to each other (so they are all parallel to one another) and spaced as shown by the basic values on the drawing (60° and on a 4" diameter).
These cylinders, are controlled to Datum A, so they are all also parallel to datum A and, and the centre of the 4" pattern is located on the axis of datum A. This pattern of tolerance zones can rotate freely about datum A to best encompass the measured holes.
The given Ø0.1 tolerance is followed by (m) which means that tolerance (Ø0.01) applies when they're at their Maximum Material Condition - for a hole, it has the maximum amount of material when it's at its smallest size. As each hole deviates away from its smallest size, you gain additional tolerance (and as the tolerance zone is a diametrical value you can simply add the difference in diameter straight on to the 0.01)
As mentioned above (by way of formula) the TP value is double the radial deviation from the nominal centre to the measured centre (because the tolerance zone is diametrical the measured deviation must also be reported in a diametrical way).
