CMM Inspection of Profile Tolerance

[Thetree]

I have a request from a customer to inspect the following (note:units are inches)


------I have a picture for this but due to forum rules I am not allowed to post it. Can anyone help?-------


Datum A is the face of the .305 diameter and there is a .285 hole through. There is no true definition of the location of the 16.000 R. Is it acceptable to assume tangency? If that is the case, does it allow for any step between the 16.00 radius and the .6615 diameter? I would assume it would allow for .0015 step. Also, would you consider the .305 diameter to be a part of the profile? There is an abrupt change in direction here, but the .305 is only shown basic and is not dimensioned anywhere else.

I am being asked to inspect this on our starrett manual CMM with apogee software and I am not confident at all in my ability to get an accurate reading due to short chord length of large radius and small datum face.

Any help would be appreciated.

Moderator Note: Added in edit: See picture in post #4.

 

[Stijloor]

I have a request from a customer to inspect the following (note:units are inches)


------I have a picture for this but due to forum rules I am not allowed to post it. Can anyone help?-------


Datum A is the face of the .305 diameter and there is a .285 hole through. There is no true definition of the location of the 16.000 R. Is it acceptable to assume tangency? If that is the case, does it allow for any step between the 16.00 radius and the .6615 diameter? I would assume it would allow for .0015 step. Also, would you consider the .305 diameter to be a part of the profile? There is an abrupt change in direction here, but the .305 is only shown basic and is not dimensioned anywhere else.

I am being asked to inspect this on our starrett manual CMM with apogee software and I am not confident at all in my ability to get an accurate reading due to short chord length of large radius and small datum face.

Any help would be appreciated.

Without a drawing, it's very difficult to advise you.

I will PM you.

 

[Thetree]

I emailed you a link to the picture. Please post it if possible. Thanks, Dan

 

[Stijloor]

Dan,

Here is the picture.

I leave it up to the CMM guys here to comment.

 

[Thetree]

If anyone could help with at least the interpretation of the drawing, I would appreciate it. Thanks, Dan

 

[Stijloor]

If anyone could help with at least the interpretation of the drawing, I would appreciate it. Thanks, Dan

The profile tolerance applies from tangent point to tangent point.
{From the edge on the .305 basic diameter to the end of the (2.38) reference dimension (The 2.38 should actually be basic too)}

The actual profile must be located within the .003" tolerance zone.
The .003" means equally disposed about true profile.
(.0015 up and .0015 down from true profile.)
Flats and reversals are permitted within the profile tolerance zone.
So a "step" at the end is permitted.
This interpretation is per ASME Y 14.5 with a disclaimer that we can not see the entire drawing.

 

[sagai]

That's magic!

All I see is dots and lines and numbers and arrow heads

Cheers!

 

[Thetree]

I was unsure about whether or not tangency could be assumed. With the 2.38 not being basic, the radius is under defined unless I can assume tangency. Thanks, Dan

 

[Michael_M]

The .305 diameter and the length (1.670) are basic so those define 'where' the profile must fit along with the actual radius.

As Stijloor said above, the profile must fall within +/- .0015 off any true (perfect) point.

 

[Thetree]

The question stands that I would like to know if tangency can be assumed. With the 2.38 being reference it does not control the feature and it could be .25 long and still hold the 16.00 radius and .305.
The 1.67 basic is not the length but the location of an internal feature. I should have removed that for clarity.
Thanks, Dan