【转帖】serration

yang686526

serration
i admit i am a bit stumped. probably not enough coffee yet!
i am working on a part that has a serrated end (din serration). the other end of the shaft has two flats milled on opposite sides of the shaft (flats are parallel).
the issue at hand is that the serration needs to be oriented wrt the flats.
my initial thought is to define the diameter of the part as primary datum a. secondary datum b to be defined inline with the dimension across the flats. i think this sets up the datums in this particular case according to our requirements.
currently my theory is to use angularity wrt a and b and the first space in the serration (not sure if my description makes sense). not great and maybe dead wrong but i have a major gd&t brain block right now.
i don't have a copy of asme y14.7.1 or y14.7.2 so i am not sure if there is information in these standards that might apply. if anyone has experience with these standards and this is covered i will rush out and nab them but i don't want to purchase them if they don't apply. i am reasonably sure they do not apply to the specification of the din serration but perhaps somewhere in one of the standards orientation of splines is discussed??
any help/guidance would be appreciated. thanks!!
find a job or post a job opening
without seeing what your applying to i can only imagine and my suggestion is purely speculation.  you still need to stop translation along the shafts axis.  typically the flats would be used as a tertiary to clock the component.  perhaps use the shaft end that the flats are on or the shoulder created by machining the flats as your secondary datum surface(s).  i would then apply a tertiary datum to be the mid-plane comprised of the parallel flats to lock the component in 6 dof.  then apply a profile of surface from point to point on the serration instead of angularity.
hope this helps.
if i'm reading it right.  the serrations are the same as spline in that they have spaces and teeth. i would call out a space on the serration and give an angularity tolerance from the center of the space to the flats.
if you can i would machine the serrations 1st then machine the flats to the space.
also tooling can be made to line up a shur-lok serration die to the flats if burrs become a problem.