When I first started using a mill I destroyed a fair number of end mills including solid carbide. After I had accumulated a drawer full of dull ones I decided it was time to try my hand at sharpening them. I bought the sharpening fixture that everyone sells for around $40 only to find that it was designed to use on a surface grinder with a magnetic chuck. Not having such a machine I proceeded with Plan "B". Using a cobalt drill, I drilled holes so I could clamp the fixture to my mill table. Then I made clamps to fit in the holes. The first set of clamps were too narrow for the tee slots of my new mill so I am in the process of making new ones. I now am able, using a cupped grinding wheel, to resharpen all my inventory. I recently bought a diamond encrusted cup wheel for sharpening carbide.
Here is what my fixture it looks like.
And what the hold downs look like. The small ones were too small.
I centered holes along each flat and up 1/2" up from the bottom. With the fixture laying on its side with the locking screw to the right, locate the hole for the front flat, centered and half inch up. Once you do this use a square to carry your center line across to the other side to locate that hole. The reason for this is the 5 degree slope on the bottom of the larger flat shortens that side of the front flat. (That slope is what keeps you from just clamping the fixture in your mill vise.)
I made the hold downs in the four jaw chuck on the lathe so I could offset the pins. I did this so the rear of the clamp could rest on the mill table and not need any further clamping hardware, just a couple of bolts and tee nuts. BTW the unfinished ones pictured are 5/8 X 1" SS because it was what I had handy.
To use the fixture I start by clamping the small flat to the table using a machinist square to set it parallel with the "Y" axis. The flute you are grinding must parallel the "X" axis. After getting that set you should be able to slip the spanner underneath to snug up the collet. You will want to work on the flute to the right of the center and use the "Y" axis to move the tool under the grinding wheel. This is because of the 5 degree slope toward the center of the cutter. After you have ground all the flutes at this angle drop to the larger flat, square up, and grind the cutting edge. Being a two fingered typist I can grind a tool quicker than I can write about it!!!
Joe
