only a minimum callout
only a minimum callout
(OP)
Hi everyone,
this is my first post so go easy please. I've got a part that my mfg engineer wants to dimension as: 3" minimum. is that an acceptable callout? what is trying to be said is that there is no limit on how long it can be, as long as the part is 3" or longer. is this dealt with in asme 14.5? is so where?
thanks in advance for the help!
this is my first post so go easy please. I've got a part that my mfg engineer wants to dimension as: 3" minimum. is that an acceptable callout? what is trying to be said is that there is no limit on how long it can be, as long as the part is 3" or longer. is this dealt with in asme 14.5? is so where?
thanks in advance for the help!





RE: only a minimum callout
Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Apr 30, 2008)
RE: only a minimum callout
Now if we are talking MAX, use this frequently for radii that are not critical. I give the machinist some freedom, if they need a radius, it can be up to this size. If they don't need it, there can be a sharp corner.
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RE: only a minimum callout
Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Apr 30, 2008)
RE: only a minimum callout
As Mad says, saying 3" min means you'll accept 4" or 5'...
Maybe this works for your part but off the top of my head I can't think of a situation that's true in.
How about 3.5 +- .5 or similar?
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RE: only a minimum callout
In the case of radii, I can imagine that if you are OK'ing a radius but not requiring it, then a max only callout might be acceptable.
In any of the cases listed by me and others here, there is always a limit of some sort in the other direction. It's just that limit may sometimes be stated in difference terms from the primary specification.
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RE: only a minimum callout
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Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Apr 30, 2008)
RE: only a minimum callout
Six inches is ok?
Three feet is ok?
Fifty feet is ok?
At some point the must be a length where you say "That's not going to work."
RE: only a minimum callout
RE: only a minimum callout
That being said, I am not saying that what I just said can be applied in blanket form across the board. The statement I make is in general, I'm sure there are situations where using MIN or MAX is not appropriate but in this case where ME2QE gives me the impression that this part is something simple like a rod of piece of tubing I think it suffices. In my specific field, material is bought and sold by the kilo. Using MIN and MAX works because you're not going to get any more than you ask for.
To answer your question, MIN/MAX is addressed in the fundamental rules as a way to avoid tolerancing a part. I don't know if it is addressed anywhere else. I think it has it's place at times but you just need to fully understand the repercussions of using it. The others here gave you the big reasons.
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RE: only a minimum callout
Yes, if it is not per print and bigger than the max tol.
Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 06/08
ctopher's home (updated Apr 30, 2008)
RE: only a minimum callout
The case is that this part is cut to length during final assembly so his argument is that there was no need to put an upper limit on it. Realistically speaking, no shop is going to send us a 12' piece if we kept it at 3" min. But just to stick with some sort of familiarity (as least for me), i'm going to stick with a lower and upper limit tolerance.
Thanks for all the advice!
RE: only a minimum callout
RE: only a minimum callout
RE: only a minimum callout
I'm curious, what is the finished size with tolerance? Is it specified on the assembly drawing? What is the process used to finish the size? Also, is this requirement on a BOM?