Intro: Porboy CNC/rotary Table
Let's say you need a circular feature on a piece you're working on. Let's say you either don't have a CNC or a rotary table, or since it's only the one piece, setting up either would take too much time.
This is a stripper plate for a die that punches a hole and rounds the end of a flattened piece of conduit that will become a geodesic dome.
Step 1: The Set Up.
To start with, the jaws on my mill vice are level and parallel. I didn't do anything extra here, it's just the way I keep things set up. It's a useful thing for a lot of reasons.
There's a conveniently placed hole at the center of my circular feature. This is required for this trick to work. The size of the hole does not matter, only the location. If your piece won't allow a hole, there are some workarounds, but I'm not going there for this Instructable.
Put a gage pin, dowel pin, or some round stock that fits snug in the whole. Clamp it in the vice with the pin setting on the vice jaws and set your cutter "Z" from the pin and lock it down. We won't be changing "Z".
Now it's just a matter of taking a cut and then rotating the part a little and repeating.
Step 2: Keep Going!
Since I was working into a corner, I turned the part around to keep things simple.
Step 3: Finished!
If you are very patient, you can get a pretty good finish by making many cuts at small angles of rotation.