Endmill End Grinding Jigs

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Andre

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Today I attempted to sharpen a ITW 2 flute endmill using the surface grinder. I used a vise, V block, shims, and a magnetic base stand for a flute index. I got the primary grinds, gashes, and center relief dialed in. It was very pretty and sharp, but I the primary edge didn't have enough center relief so it rubbed.

I have the Harold Hall book about TC grinding, and am familiar with the jigs he has made, but what are the jigs you folks use for endmill end sharpening? I am not in need of center cutting geometries, or flute grinding. Just to touch up the ends and reuse endmills with chipped corners. I have a jig in mind but would like some ideas from those who have done this regularly.
 
Watching closely -- I've recently decided that being able to resharpen the ends of end mills would be a worthwhile investment...
 
Take you a Dremel tool or air grinder with a small round rock and carefully grind the center below the surface just enough so it does not rub when cutting.
 
Sharpening the ends of end mills is very easy. It is ground like a drill is...... A primary angle usually about 7 degrees..... A secondary angle for clearance. The big difference is, the ends of the flutes are ground to a 2 degree angle to "dish" . This is so the corners of the flutes cut and the center does not rub. You can touch them up by hand on a bench grinder in a pinch or for good accuracy set the end mill up on your surface grinder to grind these angles accurately . There is a chart of angles for various diameter end mills on my tool grinder thread. You can download it there.
 
I just freehand it on the bench grinder. I use dial calipers on the larger sizes to keep the flutes the same length, and a small precision square to keep the dish angle Mark referred to approximately correct.
 
I'm watching with interest too.
I have done it successfully by hand on the bench grinder, but only for two flute end mills above about 10mm diameter. Would like a jig of some sort to handle the growing collection of 4 flute and smaller diameter one i've blunted.

There was a video on YouTube of someone using a die grinder in the lathe tool post with the end mill in the chuck. Then sharpening using the cross slide and compound. That seemed like a potential solution but I haven't tried it myself yet
 
This would be something that would be of interest to a lot of us.
 
I have found the easiest way on a surface grinder, it to use a spin indexer with a sine plate. If you don't have a sine plate, you can shim the indexer up and block all around it.
 
@TORQUIN Thanks for posting that! I have never seen those before.

I wonder how they do the index and lock feature. Could it be made in the homeshop?.....hmm...

It could probably be mocked up with a horizontal rotary table, and the proper size Morse collets for the tool shank.
But you'd still need the entire works mounted on the sine plate. That might get too tall.

Interesting.........
-brino
 
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