Parallel coincident faces
Parallel coincident faces
(OP)
I am trying to define a geometrical tolerance scheme to control two separate faces to be in the same plane.
I can define one face as a datum and control the other parallel to within a tolerance band. And if the faces were offset from one another, I could place a basic dimension which would control the distance. But since I want them coincident, I cannot put a basic dimension of '0'.
Do I need to add an additional position tolerance? Or can anyone suggest a better way to achieve a tolerance between 2 parallel and coincident faces?
Many thanks.
I can define one face as a datum and control the other parallel to within a tolerance band. And if the faces were offset from one another, I could place a basic dimension which would control the distance. But since I want them coincident, I cannot put a basic dimension of '0'.
Do I need to add an additional position tolerance? Or can anyone suggest a better way to achieve a tolerance between 2 parallel and coincident faces?
Many thanks.





RE: Parallel coincident faces
It's been discussed here before, maybe try finding it.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Parallel coincident faces
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Parallel coincident faces
RE: Parallel coincident faces
One advantage of GD&T feature control frames is that you do not always need to apply a dimension to have a tolerance.
If it is not obvious that two surfaces are coincident, you can connect them with a phantom line. In general, if they look coincident, they are coincident. This is the same problem as when you have a feature located on a centre line.
RE: Parallel coincident faces
I've attatched an approximation of figure 6.5.6.1 from this standard showing how to use profile of a surface for multiple coplaner surfaces.
http://f
Andymat, are you actually using ASME stds, if not then there may be other options. If in the UK or somewhere and using ISO there may be different ways of doing it, I've got a vague recollection of some ISO standard allowing you to use postion for this, there may even have been a previous post about it, but I can't recal for sure.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Parallel coincident faces
It is implied that the two surfaces are 0 mm (or inches) apart, and since a profile will be imposed across it, it is understood to be a basic dimension of 0.
John-Paul Belanger
Certified Sr. GD&T Professional
http://www.gdtseminars.com
RE: Parallel coincident faces
Thinking about it, a connecting line will imply that they are co-planer and with a parallel tolerance from one to the other this is probably all that is required.
I did think about using a profile tolerance but that does seem a little away from it's intended use.
I think I am making things more complicated for my self, although it's good to have a discussion.
Many thanks every one.
RE: Parallel coincident faces
ASME does not allow this.
Dave D.
www.qmsi.ca
RE: Parallel coincident faces
RE: Parallel coincident faces
Dave D.
www.qmsi.ca
RE: Parallel coincident faces
In ASME, using the profile in this way is intentional. I don't know about ISO rules, but I suspect both ASME and ISO will use the same method one day (as ASME Org is now a contributing member of the development of ISO).
With CF functionality in ASME Y14.5-2009, the flatness way of calling out the two surfaces may be allowed now.
Matt Lorono
CAD Engineer/ECN Analyst
Silicon Valley, CA
Lorono's SolidWorks Resources
Co-moderator of Solidworks Yahoo! Group
and Mechnical.Engineering Yahoo! Group
RE: Parallel coincident faces
Particularly after we steal their idea to make "CONTINUOUS FEATURE".
Frank
RE: Parallel coincident faces
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Parallel coincident faces
I am only interested in providing some support to people who work with the ISO standard when they do appear here, I have a selfish intrest, I want to learn more about it.
Frank