Composite TP for Any 3 Consecutive Holes

[[Me...]]

Hey guys,

I have a part drawing that has a straight line of holes. It states that it wants a comp TP (no datum references) for any 3 consecutive holes. Now I can make an individual alignment/position for each hole, but is there an easier way to do it? I have over 40 holes.

Thanks in advance.

[[Jo...]]

I would just evaluate all the holes like any normal composite position tolerance. If the holes come out good, then they're good. If not, then there are some holes that don't meet spec and the part is bad. The "3 consecutive holes" note seems misguided.

[[Me...]]

I believe it makes sense in this particular case. The "straight" line of holes tend to bend in and then back out. I believe this callout is an attempt to make sure the curved line of the holes isn't too severe.

[[Jo...]]

If this is a composite position tolerance and there is no datum reference in the lower tier then the only thing being controlled is the spacing between the holes, not the orientation to any datums. What datum references are in the top tier?

[[De...]]

It would seem to me that the primary purpose of this would be to maintain the alignment of any 3 consecutive holes to each other, and in this way limit the overall amount of 'twist' of the entire series of holes.

If there is no Datum reference then the check is the orientation of the pattern to itself, or in other words it would check that the holes were in line.

That said I cannot think of a great way to do the check other than creating something for each 'set' of holes.

[[Me...]]

I ended up caving and literally making a separate alignment for each hole. It was a very fun few hours.