Does anyone sharpen endmills?

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AllenH59
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Does anyone sharpen endmills?

Post by AllenH59 » Sun Apr 03, 2022 12:15 pm

I am not sure they are worth sharpening, but I have a small box of 2 and 4 flute, both HSS and Carbide that I would like sharpened. I do not have enough to justify buying a good machine to grind them with.
Thanks
Allen

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Bill Shields
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Re: Does anyone sharpen endmills?

Post by Bill Shields » Sun Apr 03, 2022 2:27 pm

yes...as long as they are good material. I save up until I have a box and send them to my local guy who does them and sends back in a couple of weeks. MUCH CHEAPER than new...

again...assuming they are good material to begin with.

Some of the imported junk is not worth fooling with the first time around...and you can tell right away..
Too many things going on to bother listing them.

Harold_V
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Re: Does anyone sharpen endmills?

Post by Harold_V » Sun Apr 03, 2022 4:08 pm

Keep one thing in mind if you intend to sharpen end mills. How much damage they have versus the diameter is critical to worthiness.
In simple terms, rake angle of an end mill is determined by the peripheral grind and the original flute generation. Small end mills (less than ¼" diameter) can be rejuvenated by simply pushing back the end (removing the dull or damaged area) and yield an end mill that performs perfectly well. Sharpening the periphery can be counter-productive because the angle (or radius) that creates the required rake angle is so small that the slightest change alters rake, rendering the endmill useless due to poor performance. Further, excessive peripheral grinding also reduces space needed to carry chips.

Larger end mills respond reasonably well to sharpening the periphery. They suffer the same fate, but the changes in rake angle are correspondingly smaller as the diameter increases. They often can be resharpened numerous times, assuming they are sharpened before there is serious degradation of the cutting surfaces. For that reason, if you prefer sharpening end mills, they should be taken out of service before there is considerable damage to the cutting edges. Once well rounded, the amount of stock that must be removed to restore them to usefulness is often enough to destroy their performance ability.

All said, I heartily support the notion of sharpening used end mills.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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Gary Armitstead
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Re: Does anyone sharpen endmills?

Post by Gary Armitstead » Mon Apr 04, 2022 10:16 pm

Endmilland ball cutter grinding is NOT for the novice or hobbyist. Many die shops where I spent my career, had many cutter grinding machines available to sharpen "used" cutters. There is/or was an apprenticeship for tool and cutter grinders. I have file cabinets in my home shop full of every kind of end mill and ball cutter. They are Weldon's-some of the best quality cutters on the planet. Still usable for me in my shop.

My next acquisition for my own home shop would be one of these cutter grinders:
https://www.ebay.com/itm/133835812925?c ... HgQAvD_BwE

BUT at $13,500, I'll have to wait for the lottery to come in. During my 45 year career, this was my goto tool. :)

The "learning curve" on the use of one of these. There is actually a code number on Weldon cutter shanks that corresponds to the settings on the Monoset that automatically sets the correct rake angle and clearance on individual cutters. Just like Harold mentioned above in his post. Grinds straight flute, spiral flute and draft angle cutters (either straight or spiral. It will also grind the ball radius very accurately (either straight or spiral and all in the same operation!
Gary Armitstead
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Member LALS since 1980
Member Goleta Valley Railroad Club 1980-1993

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Bill Shields
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Re: Does anyone sharpen endmills?

Post by Bill Shields » Mon Apr 04, 2022 10:25 pm

In other words.. find a guy that does it and marry your daughter off to him
Too many things going on to bother listing them.

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SteveM
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Re: Does anyone sharpen endmills?

Post by SteveM » Mon Apr 04, 2022 11:07 pm

When you look at the price of a new, quality carbide end mill, hell yes, it's worth sharpening them.

High speed steel, less so than carbide, but still worth it.

Keep in mind that once they are sharpened, they will be smaller in diameter.

If you have scrap carbide that can't be sharpened, set them aside and when you have enough. put them on ebay for scrap. They can get quite a bit.

Steve

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Gary Armitstead
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Re: Does anyone sharpen endmills?

Post by Gary Armitstead » Tue Apr 05, 2022 5:07 pm

SteveM wrote:
Mon Apr 04, 2022 11:07 pm
When you look at the price of a new, quality carbide end mill, hell yes, it's worth sharpening them.

High speed steel, less so than carbide, but still worth it.

Keep in mind that once they are sharpened, they will be smaller in diameter.

If you have scrap carbide that can't be sharpened, set them aside and when you have enough. put them on ebay for scrap. They can get quite a bit.

Steve
In one of the die shops I worked in, the owner had numerous 3 pound coffee cans around the shop and had us deposit broken/damaged carbide inserts and cutters in them. At the end of the year, the owner would sell them to a scrap dealer and give the money he received as a bonus to every die sinker!! Great shop to work for.
Gary Armitstead
Burbank, CA
Member LALS since 1980
Member Goleta Valley Railroad Club 1980-1993

LIALLEGHENY
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Re: Does anyone sharpen endmills?

Post by LIALLEGHENY » Thu Apr 07, 2022 1:42 am

Quick internet search came up with Accusharp in Canada. Sure there are others.

Over the years I acquired a KO Lee tool cutter grinder with all the attachments, a Weldon air grinding fixture, and many of the other assorted endmill grinding fixtures on the market. To date I have yet to sit down and regrind an of my endmills as I don't have the time ( I send them out locally) , but I have used the KO Lee to custom grind many specialized cutters for the various architectural project I get involved with. I know enough by trial and error to get by and get a working cutter that gets the job done. It's been an invaluable asset many times over.

Nyle

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Bill Shields
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Re: Does anyone sharpen endmills?

Post by Bill Shields » Thu Apr 07, 2022 5:32 am

Razor sharp in phoenixville pa
Too many things going on to bother listing them.

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SteveM
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Re: Does anyone sharpen endmills?

Post by SteveM » Thu Apr 07, 2022 8:11 pm

Gary Armitstead wrote:
Tue Apr 05, 2022 5:07 pm
In one of the die shops I worked in, the owner had numerous 3 pound coffee cans around the shop and had us deposit broken/damaged carbide inserts and cutters in them. At the end of the year, the owner would sell them to a scrap dealer and give the money he received as a bonus to every die sinker!! Great shop to work for.
An electrician I know always kept a bucket with him on the job. EVERY scrap of copper went into the bucket.

At the end of the year, he paid for a trip to Las Vegas to see a NASCAR race.

Steve

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TimTheGrim
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Re: Does anyone sharpen endmills?

Post by TimTheGrim » Thu Apr 07, 2022 9:51 pm

My 1st Toolroom job (‘74) was in a technical ceramic company. We took twist drills, cut slots and silver soldered carbide pieces to them and then ground them either in fixtures or by hand. Carbide was precious and when a tool could no longer support a diameter or form, the insert was removed and put in a drawer destined for a smaller hole production run. Carbide was never wasted.
It’s amazing the tricks you learn grinding rotary cutting tools and turret lathe form tools. When working with ceramic you have to factor in %’s of shrinkage, both diametric and linear. I got a dollar raise for making a multi flute form reamer that met specs out of the kilns on the primary test run. That outfit moved out of state and sadly family obligations kept me from going too.

Next was a die shop where we stamped electronic preforms with little die sets in small Perkins presses. My foreman gave me a “kit” to use when cleaning a die after it returned from a press run. It was a nylon stocking, a long snout plastic squeeze bottle and an 8 oz stainless can with lid. The die set was placed on a tilted trough and trichlor was liberally squirted to wash the remaining oil film and any parts or filings left there. The stocking was placed at the bottom of the tapered trough to filter out the metal from the liquid. The stainless can held the spoils. I have 15 oz of AG and 1.3 oz of AU from his tenure as foreman. When he retired and they made me Foreman I discontinued that practice. I did not not however repatriate the previous spoils.

Both of those companies are actually still in existence and I’m retired.

That Razor Sharp company looks like a top notch outfit. Thanks for that.
Illigitimi non Carborundum
'96 Birmingham mill, Enco 13x40 GH and Craftsman 6x18 lathes, Reid 2C surface grinder. Duro Bandsaw and lots of tooling from 30+ years in the machining trades and 15+ years in refinery units. Now retired

stevehuckss396
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Re: Does anyone sharpen endmills?

Post by stevehuckss396 » Fri Apr 08, 2022 3:13 pm

I am not sure where you live but in the Detroit area I took about a dozen 3/4 - 1 inch endmills in to a cutter grinder shop to be reconditioned. Cost was 90 something bucks and they were pretty badly damaged. Got them back razor sharp and a little shorter and a little thinner. I have used 2 of them in the last few years so they last a while and how many 1 inch endmills can you buy for 90 bucks. I don't even know math and i can tell that it was the way to go.

Now my pal David ran a department at general motors. Very intelligent man. He did a study where he concluded that from 1/2 inch and up it was better to get them sharpened and below that it was better to buy new. For the garage machinist it is probably 1/4 and maybe smaller because we are not paying an employee to drive them over and pick them up. Find out what it costs to refurbish and use your best judgment.

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