Profile of surface applied to irregularly shaped features with drafts

[pmarc]

Hello,

I would like to use profile of a surface to tolerance some features in my application (attachment). However the issue is a little bit tricky, because these features have got irregular cross-sectional shape and additionally drafts on the walls. I am afraid the way I did it is not exactly in agreement with ASME Y14.5M-1994, but on the other hand I think there is no suitable example in the standard that shows the method of tolerancing such type of features.

I am curious what do you think about it. Any hints or remarks?

pmarc

 

[PeterStock]

The first thing I would change is to move the profile tolerance of the outer surface to section d-d as this is where you have the dimensions for it. The second thing I would change would be to move the section a-a, section b-b, section c-c and section d-d callouts to below the views. Picky-picky I know but I am a checker now and I can be (your company standards may be different that mine but I would look under the view for the callout.) You should also check if you need to create a min thickness dimension in addition to the profile tolerances. The only thing I see missing is the corner radii arount the shoud profile and that may be taken care of in your general notes. Personaly I think this should be shown in the model as well.

Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services

 

[MechNorth]

Your profile callouts are fine. The tolerance zone is established based on the basic geometry, so the zones are inclined at your taper angle as well. If this were a casting/molding with draft allowance (i.e. not in the basic geometries) rather than dimensioned taper, then the actual surface with or without taper would have to be within the zone.

I'm not keen on using datum references at MMC for surface profile. It's like saying "here is where I want this feature to be in x-y-z-space, but now I'm going to let it shift around...". Last I can recall, CMM (contact or vision) software weren't providing the datum shift with surface profile; may have changed, but I haven't heard of it.

Jim Sykes, P.Eng, GDTP-S
Profile Services

http://www.profileservices.ca

TecEase, Inc.

http://www.tec-ease.com