Sharpening end Mills.

[toglhot]

I machined up a new mount for the new Ozito rotary tool this morning, the old one $#it itself. I made the mount to fit the flexible extension, it worked ok, but the cords running everywhere is a bit annoying, so, I’ll make another mount later on just for the rotary tool to keep the cords to a minimum.
This is my procedure for sharpening end mills, but be warned, I have no fancy tools, no QC tool holders, no variable speed, even my tool height jig has no point, I'm a rough, manual machinist in the extreme.

So first I mount the end mill in the chuck and using a straight edge, get the end mill cutting edges horizontal, then make a mark on the chuck or pulley of the lathe, make another mark 90 degrees to the first and so on until you have four marks all at 90 degrees to each other, then set up some sort of pointer.

Next, mount the rotary tool in the tool post and centre the shaft of the grinding wheel and bring the grinding wheel up the face of the end mill, switch your lathe into reverse gear and start it up. Start up the rotary tool and face the end mill until the mill is flat. You can just spin the chuck by hand if you wish.

Once flat, place the grinding wheel in the centre of the end mill and grind a divet in the middle, rotating the lathe chuck to get the divet central, the divet edge should reach the inner edge of where the flute meets the middle.

Next drop the rotary tool down a few degrees, rotate the chuck until the marks on the chuck line up with the pointer and grind the rear most flute, rotate the chuck 90 degrees at a time, grinding each flute, just make sure you bring the grinding wheel to the centre of the end mill on all four flutes.
Next, brush the cutting edges of the end mill with a diamond honer. I have a couple of diamond plates I use. The end mill should be as sharp as you can get it and should cut leaving a no e shiny surface.

You can grind a cutting edge and a relief behind that if you wish, but I don’t bother.

I started making a video, but it would have taken three weeks to upload, so, you’ll have to just look at some stills.
I prefer two flutes for aluminium, as they don't gum up like four flutes do.

 

[Signal]

Thanks that's a great idea I have a few cutters that could do with a sharpen.