Profile tolerance on a biconvex object

[kkeenn]

I have a biconvex object similar to the one that is attached (The actual object has multiple curves per side instead of just 1). I would like to assign a profile tolerance to the front and side view to tolerance it. A colleague of mine says that I can't do it because the profile of the front view changes due to changes in the left view and vise versa. Is this true? how could I apply those tolerances (ideally it would not be all over type solution). I would expect this part to be fairly easy to inspect. If the front view fits through a hole and the side view fits it will function.

 

[pmarc]

Shortly saying, my opinion is that three independent profile of surface controls for three convex surfaces can do the thing here.

 

[drawoh]

kkeenn,

I do not see how adjacent faces would affect a profile of a surface, at least from an inspection point of vierw. It would affect an edge profile, but I do not see why you would specify such a thing.

If this is welded out of sheet metal, the adjact sides will affect the profile, but this only affects the tolerances you can confidently apply. It has no effect on your GD&T specification other than on the number you type into the feature control frame.

Apply the profile tolerance to each surface of interest. Read the ASME standard. You can label two points on your orthogonal view, and apply the profile to everything between the points.

JHG

 

[powerhound]

I think two callouts are sufficient here, one on each view with between points specified; however, you should have provided something a little closer to what you're actually working with because if that front surface is actually faceted, or there are more tangent lines involved in the actual part, then I believe there is another issue and your colleague may be correct. I think you may have oversimplified your drawing. Can you provide a slightly more detailed drawing?

Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[kkeenn]

Sorry, I just reread my initial post and realized that it was not very clear.

The part is to be machined by taking a block of material and cutting the "front" profile. It is then to be rotated 90 degrees and machined using the side profile. My friend suggests that since the cross section changes (e.g. if you where to take the front and cut it every x mm you would get the 1/4 circle only in the middle of the part) a profile tolerance doesn't apply.

My response is that profile of a surface applies to the surface. I think he's getting hung up on the term 'profile'

I will consider the part functional if I can slide it through a 1/4 circle when aligned to datum A and B (the sides). Rotate it 90 degrees and slide it through a half circle when aligned to Datum A (I added these datums in the attached picture).

 

[kkeenn]

Ignore the my reponse line wasn't correctly worded. (or correct for that matter Why is there no edit?

 

[powerhound]

Profile of a surface applies to wherever the surface is. I think I understand what you're saying now and I think your friend is mistaken. Applying profile of a surface to the 1/4 circle view is fine. As you depart from the center, material will fall away in that view but it will be there when you check profile in the other view.

Anyone disagree with that?

If you click on "Preview Post" you should re-read what you typed. You will have the option to edit but once you click on "Submit Post" it's a done deal.

Powerhound, GDTP T-0419
Engineering Technician
Inventor 2010
Mastercam X5
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II

 

[pmarc]

Agree, powerhound.

One technical remark: since there are two side faces I think using profile control as it is now deals only with the one that the leader is attached to. So:
- either you add another profile feature control frame and attach it to the second face, or
- assign two bottom corners of the part that are visible in half-circle view as points A & B and put between A-B symbol beneath the existing profile feature control frame.