Dimensioning a countersunk slot on a curved surface

[Kyle2]

I have a cylindrical part with a radial screw hole pattern for flat-head screws; the application requires that the screw holes be axial slots and I'm curious what the best practice is for dimensioning this feature. See the attached image for a better description. A chamfer dimension would not be correct as the chamfer length is longer at the ends of the slot due to the curvature of the surface.
Has anyone encountered this before?
-Kyle

 

[MikeHalloran]

Man, that's ugly.

I'm sure you had good reason to do it, but do take note that if the screws don't end up at one end or the other of the slot, tightening them will coin the countersink faces because of the theoretical line contact. If the screws have to be loosened and retightened, it may not be possible to make small adjustments of location because of the brinelled impressions in the countersinks. ... but I'm sure you knew that, too.

I guess I'd dimension one such detail in a nominally normal view, as if it were an obround, then treat the remainder as an array of the dimensioned detail.



Mike Halloran
Pembroke Pines, FL, USA