【转帖】controlling radius size within a profile

yang686526

controlling radius size within a profile
what is the best way to control the size of a radius within the boundaries of a profile?
in the attached sketch, the nominal line in blue is flanked by the min and max profile boundaries. an undesirable condition is shown in pink. what controls are best utilized to ensure that the corner radius of the measured part does not exceed the min/max radius of the profile limits? specifying a locational tolerance for the center of the radius seems logical, but presents it's own limitations when measuring a semi-circle less than 180°
i can't seem to attach the file, so here's a direct link:
jszymkowski,
   why not just apply a tolerance on the radii that is tighter than the profile tolerance?  the inspector would have to check both the profile tolerance and the radius value.  a true position tolerance would not mean anything.
   alternately, you could apply a tighter profile tolerance to the radii.  what are you trying to accomplish?
                           jhg
wouldn't the application of a tighter tolerance profile around the corner radii result in a sudden step from the end of one profile at the tangency to the beginning of the next? perhaps tangency is implied?
the application of a tolerance to the radius in addition to the all-around profile should accomplish my goal. the goal being to prevent a large radius occuring at mmc or a very small radius occuring at lmc such as depicted in the picture.
i had thought of the solution you provided, but it seemed somehow unorthodox and perhaps invalid.
thanks.  
it almost looks like you would need to double-dimension the radius: once w/ basic for the profile and once with a tolerance.
have you looked controlled radius (cr) in the asme y14.5m-1994 standard (or are you taking this into account)?
matt lorono
cad engineer/ecn analyst
silicon valley, ca
a controlled radius requirement would not prevent the condition i wish to avoid. it would, however, cause the heads of people in our quality department to explode.
here is a thought:
now that i look at your second post, jszymkowski, that may be what you were suggesting. perhaps moving the d and e further out on the 'flats' coupled with a basic dim locating d and e would cover it.
jszymkowski,
   a smaller profile tolerance on the radii allows a step between the radii and the straight sides.  does this matter?
   what geometry are you trying to achieve?
                        jhg
why do you think that cr would not prevent the condition you are trying to avoid? your arc would start and end tangent to the profile per the tangency rule and no flats or reversals are allowed along the profile it must be one sweeping arc. see fig. 2-19. the line in pink would violate the cr specification if cr were to have been applied to the drawing.
powerhound, gdtp t-0419
production supervisor
inventor 2008
mastercam x2
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
i might suggest that you back up and determine the size of the radius to be functional.  drop the profile tolerance on the area of the radius and add a controlled radius.  that would appear to be more appropriate.
i think your concerns are slightly misguided, in applying the profile and additionally the radius.
hope this might be of some help.