Having endmills sharpened

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Harold_V
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Re: Having endmills sharpened

Post by Harold_V »

whateg0 wrote:There are plenty of videos showing sharpening of the ends of endmills. I used an old Craftsman 6" lathe for this with HSS endmills. Indicate the endmill in in the 4-jaw then set the compound at 2 degrees. Then pass a dremel over the ends. I need to learn more about the geometry, though. On some of them, there was a small section hanging down below the corners of the flutes, even with a 2 degree angle.
That's often addressed by grinding a slot, using a slitting blade. You should do some grinding in that area, anyway, as once the end geometry is removed, the center no longer has the ability to cut. You have to use good judgment, as you can't touch the tip of the end mill, otherwise it creates a slight taper in the periphery, where the slot that is created removes a trace of the flute. When you do go beyond the tip, the primary relief grind of the flute is removed, which is why the angle is created.

You can also kill that small area, using the corner of a sharp wheel. Hit the raised area enough to remove it, then index the end mill 90° and repeat. So long as the center is removed, the end mill will cut properly. End mills so ground do not lend themselves to plunge cutting, although they will ramp quite well.

H
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whateg0
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Re: Having endmills sharpened

Post by whateg0 »

Actually, the endmills I have sharpened that way weren't center cutting. The area that I was describing was hard to describe since it's not on all endmills. I guess it depends on how the flute is made. The area I meant is here.
endmill.jpg
On the endmills I have had sharpened, they remove that section of the tool when the center is gashed which also provides the center cutting ability in the same action.
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Harold_V
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Re: Having endmills sharpened

Post by Harold_V »

Got it! When the end mill is ground with a slight taper inward, that area should be below the tip, but as you approach a flat end, it tends to be the high spot. Often the result of not having the faces in the same plane. If all else fails, simply increase the slight angle inward, to ensure that the tips are the lowest point. You can also alter, slightly, the angle selected for gashing. That allows for the face of the grind to be slightly deeper, eliminating the high point.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
whateg0
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Re: Having endmills sharpened

Post by whateg0 »

Thanks Harold! I had considered increasing that angle, but wasn't sure how much of an ill effect it would have. I figured if the OEM used 2 degrees, or whatever it really was that I had read, then it must be "right". The more I learn, the more I learn that what's "right" often depends on what "works".
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