Machining the space for the half-moons

This was a task which was actually easier than I thought it would be.

To place the location of the half-moons, I used my sketchup model to locate where the center of the arcs would be. The half-moons are cut out of what would be a perfect 5.00″ diameter circle. I then used a pointed tool, mounted in the mill,  to locate the center of the circle, relative to where the center of the blade would be. I then “marked” where the circle would be removed by mounting in the boring head, and setting it to make a 5″ diameter circle. I lowered it onto the piece, and it cut a groove into the metal where the half-moon would go.

The material removed by mag-drill

Before beginning, I removed as much material as possible from the area with a Mag-drill, similiarly to how I did for the space for the angle blade.

Then it was just a matter of boring. Once I started getting close to the line I marked, I began inserting the half moon to see how much more I needed to machine. Once it got really close, I began taking very small passes( .005-) and checking the gap with a feeler gauge set. See this video for a better explanation:

In terms of how deep to machine these slots, they should be between 0.24 and 0.25″ above the bottom, where the blade will go. When both the angle blades and the half moons are in place, the half moons should be slightly recessed, so that the blade sits a few thousandths above the half moons.


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