EDM stones

jdm61 said:
Bill, I knew one guy who used the large medium grit DMT diamond bench stones to get the bevels nice and flat.
Click to expand...

Oh yeah- I use diamond files quite a bit, before the water stones.
 
Sinker electrical discharge machining is performed with a graphite (or occasionally copper) electrode and allows a mold maker to burn features that can not be directly milled such as deep ribs and sharp internal corners. It leaves a scale and rough finish that gets rubbed out with EDM stones. An EDM stone is a kind of die makers stone. They're sometimes commonly referred to as EDM stones, but the stones have been around a lot longer than the EDM process.

There is a wire EDM process as well that is sort of like a tiny precision bandsaw cut.

An N grade stone is soft enough to cut quickly and the slurry it forms speeds the cut and helps form a smooth even finish. A hard EDM stone that is too hard cuts slower and tends to gouge your work.
 
I ordered several sizes of EDM "N" stones from Falcon tool in 320 and 400 grit. So far I have only used the 320 and I am SOLD! Like an eraser, and leaving a crisp transition from the bevel to the body of the blade. I use a piece of 1/4" glass as a backer for my sand paper but no matter how I tried I could never wrap it tight enough to prevent softening that transition area. When I go to hand sanding I am going to try some peel and stick abrasive discs that my business neighbor uses on his DA sanders. They are 5" round but have a fairly aggressive adhesive on the back. Should stick to clean glass and he has grits up to 2000 grit.

Edit...I bought both 1/2" and 1" wide stones. After using them both I believe that the 1" widths are not going to be as useful as the narrower ones.
 
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