Having endmills sharpened

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SteveHGraham
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Re: Having endmills sharpened

Post by SteveHGraham »

It sounds like you're paying more for your end mills than I am. But then I got a lot of mine during the Enco glory days.
Every hard-fried egg began life sunny-side up.
whateg0
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Re: Having endmills sharpened

Post by whateg0 »

Harold, I'm not sure the place I had been taking tools to be sharpened could do it, but using Superior Tool this time here in Wichita, it seems they can do just about anything. The rougher I had sharpened was done in exactly the same manner they would have restored the rake on another endmill. They also can make new endmills here if a special geometry or size is needed. Kind of a cool thing, I think. Of course, it does cost more to have that done that just dressing the edges.

That's good information, though, for anybody who has or plans to have their own grinder. I suppose most people who grind their own endmills wouldn't think of the change in rake as they are removing material.
whateg0
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Re: Having endmills sharpened

Post by whateg0 »

SteveHGraham wrote:It sounds like you're paying more for your end mills than I am. But then I got a lot of mine during the Enco glory days.
My guess is that this Altrax endmill came from Enco, but I bet it was still nearly $50 then. Big chunks of carbide cost a fortune, it seems.
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SteveHGraham
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Re: Having endmills sharpened

Post by SteveHGraham »

I should also add that $5 was a blind exaggeration of cheapness based on ancient and unreliable memories, but I was guessing based on a beaten-up end mill which I would have bought new for somewhere between $10 and $20. You can still get Atrax 4FL 1/2" carbide mills for under $20 without much Googling at all.

http://www.ebay.com/itm/1-2-500-4-FL-1- ... SwcgNZEHaK
Every hard-fried egg began life sunny-side up.
whateg0
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Re: Having endmills sharpened

Post by whateg0 »

It does seem I've overestimated the value of this tool. Must've been the rougher that I was thinking of.

On another note, I guess I need to spend some money on Ebay!
whateg0
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Re: Having endmills sharpened

Post by whateg0 »

To be fair, though, even if it costs me only $17 to buy another, if I have this tool resharpened 10 times, that's $70 I've saved. I'll still take that, and I can apply that to buying additional new cutters so sharpening doesn't interrupt a project for a week. Thanks for pointing out that listing!
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SteveHGraham
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Re: Having endmills sharpened

Post by SteveHGraham »

No problem. I hope it's helpful.
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Harold_V
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Re: Having endmills sharpened

Post by Harold_V »

SteveHGraham wrote:It would have been a tidier job if I had cut the broken end of the mill off. Wonder if the abrasives I have on hand would trim it down. I have abrasive belts, angle grinder wheels, and Dremel wheels. I would not want to do it on my nice bench grinder wheels.
A belt sander/grinder is a very good choice for grinding HSS, assuming you don't intend to use the resulting edge for cutting. It's not that the resulting grind is bad, as it isn't, but a belt bunches up ahead of the cut, resulting in a rounded cutting edge. Performance is reduced as a result.
Hmm...is it a good idea to use a busted end mill to dress an aluminum oxide wheel, or is the carbide too soft?
No, it's not a good idea, as it is too soft, as you alluded, but too hard to remove grains without dulling. The end result would be a wheel that is dull, not sharp and aggressive. It would cut hot, as another reason to not do so. Use a silicon carbide or boron carbide dressing stich, each of which will remove grains without dulling, although you must use a sharp corner of either of them. If you apply a flat or broad face to a wheel, it will be dulled.

H
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Harold_V
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Re: Having endmills sharpened

Post by Harold_V »

whateg0 wrote:Even carbide can be cut on an aluminum oxide wheel, IIRC. It's just slow.
While it does get abraded, it borders on not really being ground, and quickly dulls the aluminum oxide wheel, which, in turn, breaks down quickly. Aluminum oxide is much softer than silicon carbide, which is the recommended abrasive for a vitrified wheel, but even it isn't well suited. Carbide is always best ground with diamond or cubic boron nitride.
For the record, I, too, often end up grinding a little of the carbide with aluminum oxide when relieving the steel shank before sharpening brazed carbide. I try to avoid doing so, but it's better to grind a little carbide with aluminum oxide than it is to grind steel with a diamond wheel that operates at high surface speed.

H
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platypus20
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Re: Having endmills sharpened

Post by platypus20 »

The people who sharpen end mills/saws/annular cutters, around here, are so expensive, I'm not about to spend about 85-90% of what a new end mill cost to have an old one resharpened. I sure if the end mill was large enough, the sharpen cost/buy new ratio would change for the better, about 95% of time, my end mill usage is 1/2" and below, for me, it just isn't cost effective to resharpen.
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Harold_V
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Re: Having endmills sharpened

Post by Harold_V »

platypus20 wrote:The people who sharpen end mills/saws/annular cutters, around here, are so expensive, I'm not about to spend about 85-90% of what a new end mill cost to have an old one resharpened. I sure if the end mill was large enough, the sharpen cost/buy new ratio would change for the better, about 95% of time, my end mill usage is 1/2" and below, for me, it just isn't cost effective to resharpen.
The very reason why one should push back the ends, which can be accomplished by hand, although it does take a little skill. The end mill won't leave a great surface finish (it's hard to get all teeth cutting equally), but, for roughing, you can get a lot of extra miles from what might otherwise be a junk end mill.

H
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whateg0
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Re: Having endmills sharpened

Post by whateg0 »

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.
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