Profile of a surface

[ag162]

Good Morning Everyone,
I had a situation with our Engineering Group and VP. A callout on a print has "profile of a surface to datums AB&C, with a tol of 1.5mm". The part is a rail about 550mm in length. The callout is refering to the edge surface. Basically the straightness of the part. Ok, this is the question.
If I use the profile option in pc dmis, then I have to take several points, create a line and profile dimension the line. The software will only allow a positive value. That would be 1.5.
However the group pulled the GD&T examples out of their files and according to that, then I should dimension all the points taken and tolerance them as
±.75mm.
What is the correct way of doing this????????

Thanks in Advance,
A.Gore

[\v/inston]

use form and location - make sure you enter the nominals or they are taken from clicking the cad model

[Matthew D. Hoedeman]

Either way is correct. Using the profile of a surface will (should) give the same in/out of tolerance, but by measuring individual points and dimensioning the individual points, you get instant results of IF it is out and if so, where. You simply use DIM LOCATION and use XYZT for the report axis. If these are edge points, you can also use a single surface sample hit (you should, anyway) and you can add the S axis for the surface deviation.

[Schrocknroll]

If you are dimensioning the profile to datums, make sure you have "form and location" selected, then you can dimension it +/- .75

[Jeffrey Lovely]

I like to report the points individal
if you use form and and it measures .90 = -.20 +.70
Engineers think it is bad - then you may need to do min/max
each engineer is different

[george frick]

be sure to check the print to determine if your looking at a bilateral or unilateral profile tolerance as indicated by dashed lines around the surface to be checked. if it is a unilateral profile tolerance you may have to dimension it
+1.5mm or -1.5mm depending on the callout.

[ag162]

Tolerancing

The print does not identify the uni or bilateral tolerances. It only has the control frame pointing to the edge. Under that, it has the sets of points that are to be dimensioned. Attached is the trihedron and the control frame. The strip length is in the Y, the measurable is the X.

Thanks for the Help,
A.Gore

[kbotta]

The default for Surface profile is equal bilateral.

I report each point individualy, and give the "total profile" also.
kb

[george frick]

profile tolerance

The print does not identify the uni or bilateral tolerances. It only has the control frame pointing to the edge. Under that, it has the sets of points that are to be dimensioned. Attached is the trihedron and the control frame. The strip length is in the Y, the measurable is the X.

Thanks for the Help,
A.Gore

the profile callout for unilateral or bilateral is not in the feature control frame. there should be dashed lines at the end of the arrow leader to indicate both sides of the surface to be checked (bilateral) or there may be dashed lines offset to one side of the surface to be checked (unilateral) to detemine how you apply the tolerance. if no dashed lines are apparent- bilateral tolerancing is "implied". i also report points as others have mentioned.

[J Temmen]

The only problem with doing it "as needed", is that I usually don't find that out till somewhere in the middle of the program.

[Jeffrey Lovely]

of coarse
Oh by the way
here is an updated print
Am I too late ?

[Sl33stak]

Grrrrrrrrrrr

The only problem with doing it "as needed", is that I usually don't find that out till somewhere in the middle of the program.

How timely, it just happened to me today, but it went like this.

Engineer: Jamie, I decided we'd be better off if the features on this pan face were dimensioned off of A|B|E rather than A|B|C.

Me: I already wrote and dimensioned the program using the original datum structure, I even suggested the revised way from DAY ONE, but you didn't want to do it!!

Engineer: We (head engineer and him) mulled it over for a while (2 weeks!) and decided we'd get better tolerancing from this method. (like I told them two weeks ago?)

I wish it was FRIDAY!!!

[kbotta]

the profile callout for unilateral or bilateral is not in the feature control frame.....

Ahhh....but it will be

Kev

[Paul Sarrach]

This is one of the good ones. It does usally depend on the engineers. I do it as points, And then I report only the worst case, and double it and put that on the results. I then submit the CMM Report with it. If there is any questions I revert to the Report. Some will want the +/- I will give it only when requested. And that is not to often. Right or wrong that how I do it. And have never been taken to the floor for it.

[kbotta]

That is exactly how I report it also.
kb