I'm in a bit of a quandary.

I know how to machine this, but I don't know how to call it out on a
drawing.

I'm working on the mechanical drawings for a small electronic enclosure,
to modify a purchased case by drilling some holes for some connectors.

The holes are 1/2" diameter, and are on an end of the case that forms one
wall of a well: the other wall is formed by the molded-in battery box
about an inch away.

In order for the circuit board to fit, it must be tilted at about 40
degrees, the connectors that go through the above-mentioned holes are
inserted, pushed home as far as they'll go, then the whole shebang is
rotated into place.

In order for this to work, the top edges of the 1/2" holes need to be cut
at about a 40 degree angle. The end effect is that on the outside of the
case the holes are round, but on the inside they are oval.

Assuming that the above discussion makes sense, how would one call this
out on a drawing? Just draw the hole outlines, and leave it to the
machinist to figure out how to make it all work?

The case is ABS plastic, and the way that I'm making it is to machine the
holes on a mill, but make the 40 degree chamfer with an x-Acto knife.
But the case manufacturer is putting themselves forward to machine the
case for production. I'm going to send them a case with all the bits
installed, but I'd like to send them a drawing that could at least be
construed to be correct in some sense.

Suggestions welcome. Thanks.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com