Originally Posted by
BobWarfield
littlerob, if he toe clamps, he can't cut the circle all the way around, and will have to pause to reset the clamps and will encounter the problem you suggest.
If the circle really has no internal features that allow clamping (often a small feature is enough to allow bolting down), and you want to cut the whole circumference in one shot there are a couple of approaches.
First, you can cement the part down just as you do with you router provided the cutting forces aren't going to knock it loose.
Another approach is to use material slightly thicker than the finished part. Mill the circle to finished depth. This is going to leave your milled circle edge clean, but the part is still embedded in the workpiece by that difference in thickness. Flip it over clamp the piece down at the edges, make sure there's room for the part to drop, and then facemill that thickness away to drop the part out.
Yet another approach is to mill all the way around to partial depth, and mill widely enough that you can flip the workpiece and seat your disc (that much that is exposed) in a set of custom cut softjaws in a vise. Cut the rest with the part flipped.
There's a ton of other approaches, those are some simple ones to ponder a bit.
Cheers,
BW