Profile using size dimensions
Profile using size dimensions
(OP)
Another question guys:
I am currently dealing with another spline type issue but it's a different part. The spline is the female part. The standard invoked is 1994.
The 9 spline center of the part has the minor diameter called out as a datum and it is a toleranced dimension. The minor diameter does not meet the definition of a feature of size as there are no opposed elements. There is a profile of a surface control applied to the minor diameter.
Here's the question: Since the minor diameter is toleranced and also has a profile control. Does the profile tolerance add to the +/- tolerance? If it were a feature of size, I would say no but since I don't think it really is, I'm not sure.
I'm sure the intent was to never violate the MMC boundary but we're trying to figure out if that what is legally being conveyed.
Thanks guys,
I am currently dealing with another spline type issue but it's a different part. The spline is the female part. The standard invoked is 1994.
The 9 spline center of the part has the minor diameter called out as a datum and it is a toleranced dimension. The minor diameter does not meet the definition of a feature of size as there are no opposed elements. There is a profile of a surface control applied to the minor diameter.
Here's the question: Since the minor diameter is toleranced and also has a profile control. Does the profile tolerance add to the +/- tolerance? If it were a feature of size, I would say no but since I don't think it really is, I'm not sure.
I'm sure the intent was to never violate the MMC boundary but we're trying to figure out if that what is legally being conveyed.
Thanks guys,
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II





RE: Profile using size dimensions
But even if so, profile must be applied to a true profile (read: basic dims, not +/-).
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
http://www.gdtseminars.com
RE: Profile using size dimensions
Why there is a size dimension (+/- toleranced diameter) on something that is not a feature of size per '94 edition of the standard?
RE: Profile using size dimensions
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile using size dimensions
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile using size dimensions
Now for this one; my thought is that the profile is an attempt at co-cylindricity of the minor diameter surfaces of the spline. Don't see an issue with that per-se; it will ensure uniform assembly which would/could be an issue if +/- alone were used. Opposed points (teeth) could be within the size tolerance but shifted to either side of the intended center axis. To me, +/- doesn't help here, it hinders the appropriate control. J-P, why the concern over the profile on the minor diameter of the female spline?
I've always told my students that you exclusively use (1)a FOS with a position control OR (2) a profile control (with datums) ... NEVER both because there is no indication of which has priority, and therefore they typically will fight each other in some way.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Profile using size dimensions
Thanks again,
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile using size dimensions
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
http://www.gdtseminars.com
RE: Profile using size dimensions
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile using size dimensions
Powerhound, it's illegal.
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Profile using size dimensions
Let me try the next tack -- ground that we've debated before. The standard says that profile is to be applied to a true profile. And by definition a true profile is one given with basic dimensions. The only except is for a cone, where there may be a size tolerance if neither end of the cone is a datum. So here, the +/- tol still bugs me.
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
http://www.gdtseminars.com
RE: Profile using size dimensions
Jim, you didn't miss anything, I just further clarified the geometry a couple of posts back.
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile using size dimensions
Agree with the "12 SURFACES", though not sure that "INTERRUPTED" adds value. Then again, if the radii essentially run together, you may want to put a "between" modifier on the profile control and call out "12 SURFACES"
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Profile using size dimensions
But still, that ± thing...
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
http://www.gdtseminars.com
RE: Profile using size dimensions
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com
RE: Profile using size dimensions
Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Profile using size dimensions
Jim Sykes, P.Eng, GDTP-S
Profile Services www.profileservices.ca
TecEase, Inc. www.tec-ease.com