Help defining tolerance for true position radial holes
Help defining tolerance for true position radial holes
(OP)
Working on a part that has radial holes in a cylindrical part. Hole location is (.014(M)/A/B(M)/C. C is not used on the part, A is the end of the part or the flat of the cylinder so that would be easy enough, B is actually the center of the part defined by one of the diameters of the part. The diameter for the B datum is not the same surface for the radial holes. I am trying to determine actual radial misalignment tolerance. There is no callout for angle tolerance specifically yet there is an angle location for the part.
The angles are all boxed. I understand MML just fine but I do not think I get any leadway on the MML because this is a threaded hole. .014 true position is a tight tolerance. Is there any other way to get more tolerance with this callout?
The angles are all boxed. I understand MML just fine but I do not think I get any leadway on the MML because this is a threaded hole. .014 true position is a tight tolerance. Is there any other way to get more tolerance with this callout?





RE: Help defining tolerance for true position radial holes
RE: Help defining tolerance for true position radial holes
RE: Help defining tolerance for true position radial holes
Pos tol dia .014" is not that tight for a machined part, it's roughly equivalent to +-.005".
The MMC on B is giving you some more tolerance.
I suggest you post a sketch of the tolerancing scheme etc as a picture really can paint a 1000 words when it comes to this type of thing.
My original response:
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What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Help defining tolerance for true position radial holes
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Help defining tolerance for true position radial holes
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Help defining tolerance for true position radial holes
I realize .014 is not that tight but there are other factors playing in that will make holding that tolerance tougher.
One of the big questions is how MMC might play in on the B datum to add more tolerance. Possibly TIR?
RE: Help defining tolerance for true position radial holes
RE: Help defining tolerance for true position radial holes
For how B(M) may help you take a look at section 5.3.2.2.
5.3.5.2 is an example of radial slots which might help your chord/ard (I believe chord since you're worried about the centerline of the holes).
Fig 5-24 on has a pattern or radial holes but it's really a composite position example so might cause more confusion than is worth it.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Help defining tolerance for true position radial holes
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Help defining tolerance for true position radial holes
You mentioned TIR. I don't think that would come into play at all with your callout. That's because TIR feels the actual surface, and will detect any form error. The GD&T that you mention will have no bearing on the form, so I would avoid the TIR business.
Kenat has lots of good info above, but I hope that helps too!
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems