End mill sharpening

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torker
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Post by torker » Sun Dec 09, 2007 9:49 am

Or you could gather a bunch of junk parts and build one of these. Don't laugh too hard...it works! I've only sharpened the ends with this thing and am still learning how much it will do.
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Russ

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BadDog
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Post by BadDog » Sun Dec 09, 2007 1:19 pm

Russ, that things gives me a headache every time I see it. Don't get me wrong, I like it, and I love the thought process that went into it, but... I need some asprine... ;)
Russ
Master Floor Sweeper

torker
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Post by torker » Sun Dec 09, 2007 4:15 pm

BadDog wrote:Russ, that things gives me a headache every time I see it. Don't get me wrong, I like it, and I love the thought process that went into it, but... I need some asprine... ;)
LOL! Hey Russ...it gives me a headache everytime I try to adjust it. It's got waaay too many adjustments available. I have a new gadget to add to it soon. I'ts for grinding very fine chipbreakers on HHS lathe bits.
I've sharpened about 30 em's on it now and am getting the hang of it.

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Flybynight
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Post by Flybynight » Sun Dec 09, 2007 5:50 pm

JimGlass wrote:I actually sharpen my own Endmills with the sharpening fixture show in the attachment. It only sharpens the very end of the endmill not the perifery. However, most of the time, in my case, only the end becomes dull. I even resharpen the cheap 1/4 carbide endmills.
Jim how do you get that fixtre to work properly.
I have one and I can't seem to get the thing to sharpen correctly.
Jim

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JimGlass
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Post by JimGlass » Mon Dec 10, 2007 7:57 am

Here is a quick rundown of how to use the endmill grinding fixture.

First, eyeball the cutting lips square with the fixture.
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Next, for grinding the secondary clearance angle I hold the fixture in a vise so it does not move while indexing.
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Eyeball the edge of the grinding wheel to the center of the endmill.
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Now index to the next flute. The fixture has 24 dedents. For a two flute endmill count 12 dedents for the next flute. For a 4-flute cutter you would count 6 dedents.
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Finally, grind the primary clearance angle.
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Note: 2 flute endmills are easyest to sharpen. If the endmill requires sharpening way back the cutting lips will need to be "regashed" so the endmill can cut towards the center. By the time most of my endmills require gashing the perifery is also dull so I scrap out the endmill. Carbide endmills I always regash with a 1/16" wide wheel.

This is all a summary of how to sharpen endmills. It takes practice. Do not become discouraged if the first few regrinds look and work like crap. I sharpened 5 or 6 endmills before I had one that would cut.

Jim
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

www.outbackmachineshop.com

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Flybynight
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Post by Flybynight » Mon Dec 10, 2007 7:35 pm

Thanks Jim
Thats what I was trying to do. (I think)
But, with 4 flutes. and I was always bumping one flute when I tried to sharpen the other. By the time I was done I had bumped all the flutes and the edges were all over the place.
Guess I might have to by 2 flutes and practice.
Jim

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JimGlass
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Post by JimGlass » Tue Dec 11, 2007 8:06 am

Jim;

If you bump an edge you are not actually trying to grind then something moved. That is the idea of holding the fixture with the vise. So nothing moves when indexing.

What I do is raise and lower the grinding wheel to the same depth setting. Then index to the next flute. Once you grind the first flute the crossfeed of the grinder is not moved again. In this way, all the flutes come out the same.

I was lucky to work where they charpened all their own cutting tools. While I never actually did the sharpening I was buddies with one guy that did the sharpening. I would watch him sharpen the cutters while we made hunting and fishing plans.

It takes practice and patience similar to sharpening drills but at the same time it ain't rocket science either. To beging with, practice on endmills that are just a little dull where some touch up is all that is needed. Then advance yourself toward endmills requiring more aggresive sharpening. For endmills that have been crashed you will need to determine the value of the endmill and value of your time to recondition it.

Jim
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

www.outbackmachineshop.com

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Flybynight
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Post by Flybynight » Tue Dec 11, 2007 9:13 pm

Guess I don't have the right equipment.
I just move the fixture into the grinding wheel ( It is fixed no up or down movement).
The bumping is hitting the "Upside flute" 90º from the wheel as I try and get into the center of the endmill as I am sharpening the flute under the wheel.
Since the fixture holds the end mill at an angle the one flute on the back side of the fixture is higher than the others and as I get closer to the center of the flute I am trying to sharpen it bumps the higher flute.
As you stated 2 flutes would work (hence no higher flute 90º to it)
Just don't use 2 flutes darn it :?
Instructions with the fixtre would have helped.
But, that is why we have the forum, so guys with all the know how can help up dummies.
Thanks
Jim

Bruce Griffing
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Post by Bruce Griffing » Tue Dec 11, 2007 10:31 pm

I also have a Darex E-90. Mostly I sharpen the ends. But I do sometimes sharpen a few larger end millls along the flutes. I also have a diamond wheel for carbide (CBN for steel). If you use your shop regularly, it is very worthwhile buying or making a setup to do this. An air spindle is essential if you want to sharpen the flutes. It comes in very handy when you need another end mill on a Saturday night.

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carlquib
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Post by carlquib » Mon Dec 17, 2007 7:59 pm

Jim,

I have a quick question if you don't mind. What wheel do you use when you are sharpening HSS end mills on your surface grinder? Do you use a finer harder wheel than for normal grinding? I can't tell anything from the picture except that the wheel appears to be white. It seems like I read somewhere that the harder finer wheels maintain their sharp corners better. Do you have a wheel that you use for carbide? I saw the post by Bruce after your's where he mentioned that he is using a CBN wheel for steel and a diamond for carbide. Is that really necessary?

-brian

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JimGlass
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Post by JimGlass » Mon Dec 17, 2007 9:07 pm

For the larger endmills and counterbores I use a 46 grit wheel. The smaller HSS endmills (under 1/4) are Chinese. At $2.50 a piece they are not worth sharpening.

The fine grit wheels do hold a corner or shape better than the coarse grit wheels. However, the fine grit wheels are slower cutting and will require more frequent dressing. For hardness, most of my wheels are in the
H, I or J area. Never experimented with wheel hardess.

The diamond wheels are for sharpening carbide endmills. I probably sharpen more carbide than high speed endmills. The 1/4 carbide are $10 to $12 each a little more worth while to sharpen.

Jim
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

www.outbackmachineshop.com

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carlquib
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Post by carlquib » Tue Dec 18, 2007 12:47 am

Jim,

Do you have a diamond wheel for your surface grinder or do you use something else to grind your carbide endmills? It isn't really an issue for me yet as almost all my endmills are HSS. I only have a few insert type endmills and a couple carbide endmills. The insert style I can usually sharpen a few times on my accu-finnish unless I completely destroy the insert.

Do you have something that you use to sharpen the flutes of your endmills? I have been looking at building a Quorn, but until I get that done I will have to make due with the surface grinder. I have an endmill sharpening jig like yours coming and am looking forward to giving sharpening a try.

-brian

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