Holes in-line

[Jeano]

I have a Feature control frame on print that readsT.P. 1.4 - 4 HOLE IN LINE. I understand the concept, but cannot figure out how to mathematically calculate this. Can anyone help?

[Kelly_Bramble]

Welcome to Engineers Edge!

Well, images are always better--- If I read you right; this should mean that the as-built axes of the four holes must simultaneously fall within a cylinder 1.4 (mm?) diameter.

I assume the calculation you want is the inner boundary of the four holes? This would be MMC size minus the position tolerance.

One would assume that one hole is offset maximum permissible by the position tolerance from the other three holes and this would represent the collective inner boundary.

[Jeano]

Yes pretty much want the holes to be concentric. I gage them but I am needing to show this callout to the customer. Yes, is mm.

[PinkertonD]

Hi Jeano,

That to me looks like an Assembly Reference to a detail drawing of the individual part. Is there a call-out drawing number for just that bent piece? That would have the dimensions for positioning it. Other than that I would not be trying to decide where to position those holes.

[Jeano]

Yes I have the nominal dimension from CAD. and I have the Measured and Deviations from the product. Just trying to calculate the actual position the way they are calling it out.

[PinkertonD]

But, as I said, I suspect that is a reference to make sure that all four holes are aligned on a common center line for ganged use. It is more of a jig/fixture issue than trying to dimension it relative to an edge or Datum. Justa guess mind you. A call to the original designer would be the safest thing to clear it up.

[Belanger]

Kinda strange that there is no MMC modifier after either number. Perfectly legal, mind you, and you can report the position measurements based on a CMM or whatever. But approaching it from a functional point of view, that could be a legitimate question to raise.