Profile of a Surface Question
Profile of a Surface Question
(OP)
Good morning everyone. I was wondering how you could interpret this situation:
A box with a profile of a surface of .010" on the top surface, and a second profile of a surface callout of .020" on the bottom surface.
What controls the thickness? And what would the tolerance be?
Thank you in advance for any and all replies!
A box with a profile of a surface of .010" on the top surface, and a second profile of a surface callout of .020" on the bottom surface.
What controls the thickness? And what would the tolerance be?
Thank you in advance for any and all replies!





RE: Profile of a Surface Question
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile of a Surface Question
RE: Profile of a Surface Question
Solid model has to be properly documented.
There should be note somewhere in the model or on accompanying drawing, saying if part was modeled at MMC, LMC, basic, etc.
This way you know what dimensions you derive from the model actually are.
That will be the start.
RE: Profile of a Surface Question
I don't know what your specific role is but if you are programming the CNC and/or machining it yourself, this is information that you also need to know, not just the inspector.
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile of a Surface Question
It is possible to apply GD&T directly to the model, but everyone should see it when opening file with proper software.
RE: Profile of a Surface Question
If there are no datum references in the Profile callouts, then they do not control the thickness. The two callouts would control each surface individually.
I'm not sure where your inspector is getting the idea that the model controls the thickness. The .010" surface being a datum sounds even more incorrect. It's fine to use the model to extract theoretically exact dimensions, but the model itself does not impose anything with tolerances or datums.
Evan Janeshewski
Axymetrix Quality Engineering Inc.
www.axymetrix.ca
RE: Profile of a Surface Question
One question:
Assuming, just for fun, that in OP's case there is a basic dimension between top and bottom surface of the box, will the two profile callouts without any datum feature references be controlling thickness, or in other words a distance between two planes of the box?
RE: Profile of a Surface Question
I think it gives some understanding of where part material should and shouldn’t be…
RE: Profile of a Surface Question
Your answers are always welcome. So if I understand your graphic correctly, you are saying that the profile callouts in conjuction with a basic linear dimension do control distance between two surfaces. Am I right?
RE: Profile of a Surface Question
RE: Profile of a Surface Question
1) CH, there is no GD&T in the model, just the part itself.
RE: Profile of a Surface Question
RE: Profile of a Surface Question
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile of a Surface Question
RE: Profile of a Surface Question
This response does not apply to the positional callouts.
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II