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Perpendicular GD&T on a Radius cut???

Question asked by Kevin Andrews on May 2, 2018
Latest reply on May 3, 2018 by Kevin Chandler

I have a situation where I am having to produce a drawing for an additional machining step to be done after the original machining was done.


In other words, someone screwed up and did not allow enough clearance for a couple of bolts in a cylinder head. Since there is already a drawing for the original machining operation, I am simply providing details for the additional machining to be done for clearance. This drawing will only be used for the previously machined parts. I will provide a revision drawing for the casting and machining going forward.


Since the cylinder head is cast, there is draft added to the pull direction. The inside of the cylinder head (the cavity) does not get machined - just the mounting holes and the mating surfaces. This means that the inside walls of the head have draft on them as well (1° draft). Please refer to picture below:


The plan is to have the machinist use a Ø3/8" end mill to do a plunge-cut in one corner and then mill over to the other corner. The depth of the plunge should be 0.357 from the finished, previously machined, surface [A]. The distance from the inside edge of the cavity is less than 3/16" (less than half the cutter Ø).


This clearance cut MUST be perpendicular to the face of the finished surface [A]. When I am detailing the drawing, I am calling out the radii on the cuts because it is not showing as a hole. I am applying a perpendicularity GD&T with a tolerance diameter of Ø.016 in reference to datum A. However, this looks a little strange to me. Anyone else ever encounter a GD&T callout for axis perpendicularity with a diametrical tolerance?? See detail below:


Does this look odd or improper to anyone else?


Sorry for such a long description and question