profile and MMC 5

[dho]

[.005][(B) mmc] applied to inside wall of the rectangular shaped can (cover). B is a hole at the can bottom. the hole has +.002/-.000 on its diameter. how can i apply MMC to this bilateral profile? bump .005 to .007 or else?
thanks.

 

[dho]

What I meant was, in your example, it could be read as

[prof][.5][B(M)] = [prof][.6(U).25][B(S)]

 

[pmarc]

No, it could not .
These are not equivalent callouts (even if you correct the second one to [prof][.6(U).35][B(S)]).

Like I suggested, think of minimum and maximum size of rectangle allowed by the callouts.

For [prof][.5][B(M)]:
- min. size of rectangle would be 1.50 x 2.50;
- max. size of rectangle would be 2.50 x 3.50;

For [prof][.6(U).35][B(S)])"
- min. size of rectangle would be 1.50 x 2.50;
- max. size of rectangle would be 2.70 x 3.70;

Since they result in different extreme sizes of the outline, they cannot be considered equal.

 

[MechNorth]

My apologies, gents, and thank you for the graphic, pmarc. I think that my mental gaff there comes from my mental bias towards using CMMs for verifying profiles, which is stupid because I teach people how to check profile in open-setup. CMMs still don't address datum shift in a profile callout (as of a about 18 months ago...do correct me if I'm out of date), which makes them useless in that environment. As pmarc clearly, and nicely, illustrated, there is an appreciable difference otherwise. I must watch that more carefully when I teach.

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

http://www.profileservices.ca

TecEase, Inc.

http://www.tec-ease.com

 

[SeasonLee]

pmarc

A star for your valuable profile MMB post.

SeasonLee