huangyhg

gd&t question regarding teeth on sprocket
this part is a sprocket with 21 teeth. the attached drawing provides enough information to construct the teeth profile (i've verified by starting from scratch in cad and recreating the profile from the dimensions.) my question is: can someone comment/verify the profile callout as a means to:
(1) ensure proper tooth form (ie the roller bottom radius has a +0.09/-0 tolerance; etc)
(2) ensure alignment with keyway (it is important that the keyway have a certain angular alignment with the teeth)
the attached pdf has comments enabled.
thank you very much!
potrero,
if your part were a gear, you would not try to specify the tooth form. you would simply quote an agma precision number. this saves a lot of work for you, for your fabricator and for any inspectors. i have never called up a sprocket like yours. you should investigate the standards. you may be reinventing a perfectly servicable wheel.
if you are concerned about clocking, you could call up your slot as datum_c, and apply a position tolerance to one of your teeth.
drawoh,
thanks for the reply. the tooth is not a standard profile, hence the need to spec it out. regarding the idea of calling out the position tolerance on the tooth; i had initially done just this (position tolerance on the center of the tooth bottom arc), but i'd removed it because technically none of the arcs that make up the tooth profile can be considered features of size. your thoughts?
potrero,
if your tooth has a specified location, it can have a position tolerance.
if your geometry is too weird for position tolerances, you can use profile tolerances and a composite tolerance block. i assume your tooth form is very much more accurate than your location.
|profile|0.05|a|b|
|profile|0.2|a|b|c|
how does this look folks?
jhg

jhg,
regarding the tolerance of position, i don't think that it's because the tooth geometry is "too weird", but that since the teeth aren't a feature of size, top isn't applicable.
on the other hand, i think your suggestion of a composite tolerance block is great. it allows tight tolerance around tooth profile and less tight tolerance about location (just as you say).
thank you.
would both of the items in the composite tolerance block have the callout "between m & n"? or just the
|profile|0.05|a|b| ?
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