section view edges

Hello

Imagine a diecast box with bosses that stick up through the circuit board
trhough holes in the circuit board. The shape of a couple of the bosses has
to change to let the mold flow better, so now the shape of two of the holes
in the PCB have to change. I set a section view in the assembly at the PCB
bottom face height, so it "trims" off the bosses. I want to offset (in the
plane) the trimmed edge of the boss and have it provide the clearance hole
in the PCB. I thought I could set a new sketch at the cut plane- I know I
can't use the actual cut face- so I used a plane the same height as the
bottom of the PCB. I select the edges of the cut-off bosses and try to
"convert entities" so I can use these in my new sketch, but it won't let me.
I tried one segment at a time, and selecting the whole chain one after
another.

Am I way off here? Can someone please point me in the correct direction?

Thanks

Bill

 

Thanks very much. I'm going to try that in the morning.
Bill