Hole tolerance to a certain depth

[mechanate]

Hey guys, I've got an interesting question here. I've got a 2.500-2.503" hole that needs to hold that tolerance through a depth of 6.625", after that the tolerance can loosen up to 2.50-2.53", at least, to a depth of 6.875". Is there a specific way to illustrate this on the drawing, or is this something that should just be supplemented with a note? I can't find anything in Y14.5 relating to this particular case. Thanks in advance!

 

[ctopher]

Look up 'Projected Tolerance Zone'.

http://www.tec-ease.com/tips/october-97.htm

Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion

 

[MadMango]

ASME Y14.5-2009
Reference 7.4.1 Projected Tolerance Zone, and Figs 7-21 and 7-22.

"Art without engineering is dreaming; Engineering without art is calculating."

Have you read faq731-376 to make the best use of these Forums?

 

[pmarc]

I am not sure that Projected Tolerance Zone concept is a proper one in this case. It is typically used when one wants to control orientation of FOS's axis outside the feature but not inside. Infact in this case we do not have any position tolerance.

mechanate, unfortunately I am also not able to find anything in the standard that could help you. It might be silly, but maybe this hole should be considered as two separate holes with two different size dimensions? I am curious how this hole is going to be manufactured.

 

[Belanger]

I agree that this doesn't sound like a case for a projected tolerance zone. You may have to just create a view where the different segments of the hole depth are labeled with A, B, C (and shown with basic dimensions), and then write the different size tolerances with a note tying each to "A" etc.

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

 

[ctopher]

If you don't want to use Projected Tolerance Zone, you can make a section view of the hole, dim the hole to 6.625 with tol, then add another dim indicating the remainder depth tol.

Chris
SolidWorks 09 SP4.1
ctopher's home
SolidWorks Legion

 

[fcsuper]

When a standard doesn't spell out a method, you can still employ a special specification on a drawing. You just have to express it completely within the context of the drawing in the form of notes or dims where the meaning is very clear.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

http://groups.yahoo.com/group/solidworks & http://twitter.com/fcsuper

 

[dgallup]

We do this kind of thing frequently. Define a zone either with basic dims or in your case perhaps a 6.625 min. Then specify the size tolerances in each zone.

In your case, I don't see this buying you much manufacturing tolerance though. The remainder of the hole is only .25" long and you are only allowing more tolerance in one direction.

 

[KENAT]

Depending which end you're coming from etc, maybe you could just dimension it as a counter bore since the mean dimension is different?

Or a section and spell it out. You can apply different surface profile tol's to different portions of a profile per 6.5 ep figure 6-13. So why not extrapolate similar to your situation.

I've done this for various situations.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[SDETERS]

Can you specify a limited length please look at asme y14.5 1.7.3 I know the illustration shows it on a shaft But I think it could work with a hole?

 

[KENAT]

Well spotted SDETERS, that's exactly the king of thing I was thinking of and have used. I forgot there were examples early on like figure 1-11.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[mechanate]

1.7.3 looks like it does the trick. I actually just ended up taking a section of the hole, drawing the first portion at its lower limit and the second portion at its upper limit so it would be clear what diameter and length I was dimensioning, then just adjusted the tolerances accordingly. The hole on the drawing ended up looking like a funky reverse countersink but it appears to have gotten the point across. Thanks for brining 1.7.3 to my attention though, I must have glossed right over that (it's kind of easy to get glossy eyed reading through Y14.5 anyway) and will most likely use that method in the future. Thanks again.