Originally Posted by pbc
Thanks, next dumb question of the day. For the router, just a simple cutting bit to cut the circles? I.e., I know with a jig saw they have special "curve" saws.
You don't need a special bit, although a solid carbide spiral up-cut (1/4" for cost reasons) will plunge straight in and do a good job getting debris out of the cut.
I wouldn't remove more than 1/4" per pass and you don't want to push hard enough that the router slows down (that will burn out the bit and may break it).
You can either anchor both the outside and inside (discarded) pieces to something solid, or stop just short of going all the way through (under 1/32") and finish with a utility knife or jig saw (you can clean it up with a flush trim bit)
Also, if I wanted to "flush" mount the terminal cup (there's about a 1/8" lip), do I use the same bit with the driver or is it a different bit?
You can. It'll work good in MDF. In plywood the up-cut spiral can cause the surface veneer to splinter so I use a straight flute for recesses (that means plunging while the router is moving for standard straight bits without a plunge tip that cuts all the way across).
Be sure to cut the recess first.
You could also use a rabbeting bit after you make the main cut-out, although making the rebate first with a normal bit is easier because the router is fully supported and you have a lot more options on how wide it is.