Before I waste time and $....

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curtis cutter
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Before I waste time and $....

Post by curtis cutter »

Would there be any reason why I could not mount my CBN wheel in the milling machine horizontally and use it to sharpen an end mill by clamping it in the vice and running the table in and out remaining parallel to the wheel? I just have a bunch of mills with slightly chipped edges and would like to clean them up.

Understand that I am not looking for perfection as I am not by any stretch of the imagination a craftsman.
Gregg
Just let go of it, it will eventually unplug itself.
Conrad_R_Hoffman
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Re: Before I waste time and $....

Post by Conrad_R_Hoffman »

I've done similar things and it can work, though it's a poor substitute for a grinder. Speed is usually too slow, you can't dress the wheel and it makes an abrasive mess on the mill. You'll also need to hold the end mills at a double angle, something like 15 degrees for the cutting angle and a few degrees so the outer edge cuts first.
Conrad

1947 Logan 211 Lathe, Grizzly G1006 mill/drill, Clausing DP,
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Harold_V
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Re: Before I waste time and $....

Post by Harold_V »

As a matter of need, I've done the odd grinding job on my Bridgeport. The time it takes to mask the machine generally exceeds the time spent grinding, but it bailed me out on all occasions, where I had no other options. In fact, I made such a setup just a week ago. As my mill has a top speed of 4,200 rpm, speed isn't a factor, although the inability to feed rapidly tends to limit how much you can do. You likely wouldn't have to worry about over speed with a CBN wheel, but vitrified wheels (like the common aluminum oxide type) might be risky to run, as anything over 3,600 rpm for the typical 7" wheel is likely to be too fast. Be very careful about spindle speed if your mill runs faster than that. Small cup wheels shouldn't present any problems at all.

As dressing isn't a part of using a CBN wheel, you wouldn't be plagued with a large amount of damaging swarf, but anything that comes off a grinding wheel is fine enough to get under wipers and get permanently imbedded, so I strongly recommend you mask accordingly if you wish to pursue your idea.

There's a holding device on the market that will hold an end mill in the proper attitude for sharpening the end. I don't have a link, and don't even remember what it's called, but you most likely would enjoy success simply doing a search online.

Sharpening the periphery requires a spindle with a finger, so unless you intend to pursue that acquisition, you won't be able to sharpen them that way, but in a way that's not exactly a bad thing. If you dull the ends, you can continually push them back, keeping the full diameter, and the required rake angle, so they cut well. End mills have a finite life and lose their ability to perform with each sharpening of the periphery.

You'll have to gash the end mill to restore the geometry required for handling chips (and for proper cutting), but that can be done by hand if necessary. It wouldn't be very pretty, but it would work. It's best done with a narrow wheel, and is often done with a slitting (cutoff) wheel. The gash creates the necessary end rake angle, so it can't be ignored, otherwise the end mill will have great difficulty plunging. It wouldn't be required if you used the end mill strictly on the side, however.

As Conrad said, end mills are not ground flat. They should have a taper (1° inward is enough) so they make contact only at the periphery. The end mill holding fixture I mentioned does that for you, and allows for indexing.

H
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curtis cutter
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Re: Before I waste time and $....

Post by curtis cutter »

Gregg
Just let go of it, it will eventually unplug itself.
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SteveHGraham
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Re: Before I waste time and $....

Post by SteveHGraham »

CBN on machine tools. That's an interesting idea. I assume there would be little or no abrasive dust to cope with.
Every hard-fried egg began life sunny-side up.
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Harold_V
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Re: Before I waste time and $....

Post by Harold_V »

curtis cutter wrote: Sun Jun 17, 2018 7:10 pm Similar to this Harold?

https://www.ebay.com/itm/End-mill-face- ... 3516231492
Yep! That's the one. For a guy who has no cutter grinder, it could prove to be a valuable asset.

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