Cutting down endmills?

Yup, and nope..sure dont. On the list, though they tend to be extremely large, bulky and of limited use to me.

Ive got a couple centerless shops who would do a brother-in-law job for me..but where is the fun in having someone else do it?

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

You don't. That's a stupid idea, hardly worthy of your time, Gunner. You'll never achieve the level of precision necessary to achieve a good running end mill. Further, unless you have a good precision grinder, you're in for one hell of a rough time grinding the shanks, anyway. It will require flood cooling, or you'll heat the shanks red hot grinding them. Turning would be difficult, but not impossible. The interrupted cut would raise hell for sure.

The only way I can think of to do this job reasonably easily is to do as Jim suggested, part them on a cutter grinder, then infeed them in a centerless grinder to reduce the shank size. You'd have a fair chance of staying concentric. If you're really hell bent on running them, and have no access to a centerless, cut them in half, bore a sleeve that is a snug fit with the end mills, then hold the sleeve in your 4 jaw and dial it in two places. You may be able to hold a half thou that way. You'll also risk the end mill moving, or chipping the periphery by chucking pressure. As I said, bad idea all around.

Harold

runs cooler and

Ayup. I was getting a beautiful finish. My OD grinder is a Covel 512, with 10 gal of grinding oil in the coolant tank.

Gunner

That rifle hanging on the wall of the working-class flat or labourer's cottage is the symbol of democracy. It is our job to see that it stays there. - George Orwell

This is obviously "a long run for a short slide", but if I was stuck absolutely positively having to do that job I'd probably approach it this way:

Chop off one fluted end.

Use one of the low temperature melting Cerro alloys and "pot" the full length of the remaining fluted end centered by eye inside a 7/8" I.D. mold. The mold can be made from almost anything, even wood.

Holding the Cerro Alloy end in a 3/4" collet, grind the end mill shank to 1/2".

Melt off the Cerro Alloy.

QED

Maybe you can teach the guy who owns those end mills how to do it himself.

Jeff

Well I think everyone was dancing around that idea but wasn't brave/blunt enough to simply blurt it out. Thank you harold. It had to be said at some point.

Jim

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You have to hold onto some of the shaft in addition to the flutes and that will end up being very little material for holding the mill. Holding by the flutes will destroy the collet in short order and if the flutes are not a spiral, there is no possibility of holding the mill without cocking. It would be fun to do to the guy if you really consider the guy to be an idiot in many ways.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

My mamma taught me not to lie! :-)

Harold

runs cooler and

Cool -

I mean Good job !

Martin