Hansrudolph as requested a sketch of some of the parts for the End mill/slot drill filing/honing jig.

The size depends on the length of the diamond files/laps you will be using. The important thing which controls the size of the end mills you can sharpen is the distance between the rollers, which must rotate easily on their shafts.

It is very important to know how far apart the centres of the holes (5/16” x40 TPI) are which carry the rollers. The rollers are pushed onto the shafts. Flanges, control the file, are to the inside. The rollers are held in place by 5BA/3mm screws and washer. The screws are threadloked in place. These screws are used to adjust the rollers across the face of the tool. Each one is locked by a ‘slim’ 5/16” x 40 tpi nut (not shown

I have omitted base plate which is screwed on to the bottom of the block and has an adjusting screw to raise and lower the platform (also omitted). The bottom of the tool being sharpened sits on it.

The size of the rollers is the ‘Tricky Dicky’ stuff. The honing angle is controlled by the differences in the diameters of the rollers. If the honing angle is 5° and the roller centres are 25mm apart then the difference in the roller diameters is 2 X 25 X Tan5 = 4.37mm. Which way round you set them up will depend on the cutter being filed up. Since the tool is upside down, the larger roller is always on the side which faces the cutting edge. It is easier to make a new large roller than to mess about with complex adjustable roller carriers and set them.

Setting up the tool and using it

Select the worst face of the tool and set the edge to be filed parallel to the rollers. Adjust the rollers so that flange allows the file just to clear the central edge of the cutter. Next adjust the height of the tool to allow you to file out the damage. Lock everything up and start filling until the file stops cutting. If you are taking a lot off the cutter check now and again that the cutting edge is still parallel to the rollers. Remember that cutters are often spirals

Hope it helps