【转帖】angular true position

yang686526

angular true position?
i am a little stumped here.  i have a part which we laser etch 3 small rectangles onto.  the laser etching is called off of the centerline of the part, at 12 1/2 degrees 3 places.  it has the true position box around it.  the only tolerancing on the pads is a width of .120 +/- .020, and a box which gives .030 max material.  how can i transfer this to an angle and find where i am?
if the angle is basic, there should be a geometric tolerance governing the attributes of your target pads.
trickysheep,
   when you say "true position box", you mean that there is a box around the dimension designating as basic, right?
   it sounds like your drawing is missing tolerance boxes.  you can apply a true position tolerance to your boxes.  another option is profile tolerances.
   without any of this, i would regard your drawing as uninterpretable.
                            jhg
there seems to be lots missing here. does the angle have a rectangular box around it? if it does, it is basic (theoretical).
positional could be of the 3 holes but it must be relative to each other or to some other datums? mmmm?
dave d.
agree with others, there seems to be a lot missing here.
kenat, probably the least qualified checker you'll ever meet...
what is the laser etch for? is it part of helping in making the part or alignment within an assembly? if it's for some type p/n marking, etc, the gd&t is probably not needed.
chris
solidworks 07 4.0/pdmworks 07
autocad 06
the 12.5 degrees is basic.  the only thing i have to go on for a tolerance block is the pad callout of a|b m | Ø.030 m
with the "m's" being the max material symbol.  a is the backside of the flange, b is the o.d. of the flange.  the pads run from the i.d. of the part out and are spaced 120º apart.  having .030 + the max material, i don't see how i can figure out any radial tolerances out of this....am i wrong?
does the feature control frame not even give the fact it's positional?
are the 120° not basic?
the length of the pads are given by the geometry of the part right, running from id to od?
kenat, probably the least qualified checker you'll ever meet...
trickysheep,
can you gain read access to the underlying cad model (assuming there is one)?  if you can view it or access it you might be able to find your missing information.  i have encountered drawings that had lots of information on feature tolerances etc, but nothing to tell me the basic size of the part.  instead we were to refer to the cad model as the master for the geometry.  i would have been ok with that except that we had no read access to the models in order to bring them up.
regards,
there is no cad model.  the pad length is given as a minimum, with the start point dimensioned at .825 +/- .040 from center of part.  the 12.5º and the 120º are both basic.
the pads run from i.d. to o.d..
the positional tolerance on the pad width should strike your zone on the 120° basic c/l's which are set up 12.5° off of another feature? the positional should not have the Ø tolerance zone then, and from the sounds of it, a tertiary datum as well.