General Note will give Tolerance for Hole Location Dimension? 1

[CATchecker]

Hello,

This is my first question after my registration. I found this site
when I am searching answer for my question.

My question
1. General tolerance (UNLESS OTHERWISE SPECIFIED ALL EDGES AND SURFACES PROFILE TOLERANCE 3 DATUM A, B and C) will give tolerance to hole locating dimension. For the hole size tolerance shown, but no position tolerance feature control frame.

 

[KENAT]

Profile combines size & location tolerance (+ orientation where applicable) into a single tolerance.

So if you have a default profile tolerance that does control the holes.

With classic size & position call out they tell you where the center needs to be (with a tol) and how far the edge can move from that.

Profile is specifying directly where the 'edges' can be.

Note, this doesn't mean that default note is necessarily a good idea or the correct control for all holes but yes, it does cover them.

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[CATchecker]

Thanks.

But if the size tolerance shown for the hole. when the general tolerance covers the location of hole then it will also cover size of the hole.Then there will be conflict between size tolerance and profile tolerance?

correct me if am wrong..!

 

[KENAT]

Sorry, didn't read your last line properly.

Yes, you have a problem.

Either size & position is covered by the profile tolerance or else you are correct - if separate size tolerance is provided for holes then you'll need to have position tol too.

While I think it's been debated on here before, my understanding is you can't combine direct size tolerance and profile tolerance.

What drawing standards are you working to out of interest.

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[CATchecker]

Thanks.

My drawing standards based on ASME. Do you have example(images or pdf's) to show that this not possible. I know about this, but unable to convince my counterparts.

 

[KENAT]

Look at section 6.5 of asmeY14.5m-1994 where it talks about using basic dims, undimensioned drawings (essentially MBD) or formulas.

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[axym]

It's an unusual practice, but I don't think that there is a conflict between a profile tolerance and a size tolerance on the same hole. The profile tolerance would control the location, orientation, size, and form of the hole. A size tolerance could be specified along with the profile, to refine the size and form. So as long as the size tolerance is a refinement i.e. smaller than the profile tolerance, then I would say that the standard allows it.

Whether this was the intent on the OP's drawing is another question entirely.

Evan Janeshewski

Axymetrix Quality Engineering Inc.

http://www.axymetrix.ca

 

[pmarc]

Evan,

A question:
What would define size (not width) of profile tolerance zone if dimension for hole diameter was directly toleranced - let's say dia. 9.9-10.4? Would you like to use additional basic dimension just for defining size of profile tolerance zone?

 

[Belanger]

You cannot have a size tolerance on a hole which has a profile tolerance on it. The only exception is if it's a tapered hole.

Why? Because profile on a hole is an all-around thing, so it naturally controls the size and shape of the hole (and orientation and location, usually, with datum references). The ASME standard does mention that profile tolerances must be applied to a "true profile" and by definition a true profile is one with basic dimension for its shape.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems