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Surface Grinding question

Last night in a fit of insomnia, I decided to mill a .125 lip in the top of both of my mill vise jaws, to hold small parts.

My vise is a decent copy of a Kurt anglelock, so I chucked up an endmill, figured speed and feed, and started taking the cut, on the first jaw. BANG! busted the endmill.. $#@! hummm ok..maybe the removable jaws are a bit harder than I thought....chucked up a brand new 5/8 4 flute carbide endmill, turned on the coolant, and started to mill...

When I got to the far end of the cut..I was shocked to see that the end cut had gotten deeper and deeper and deeper into the jaw...shit..it had moved in the collet. $&^%!!!!!!!!!!!!!!!

Ok...installed a endmill holder, ground a flat for the set screw..lets try this again, another .065 back from the edge.... Cool! nice clean cut. Move it back another .06, and finish the cut. Way cool!

Moved to the movable jaw, put a pair of 1/2/3 blocks between the jaws, to keep the movable jaw parallel, and started milling. Going was a bit harder this time..but was chugging along, making a nice shiney chip. Finished the cut..and #!!!!%$ the damned jaw was so freaking hard it had actually rounded off that solid carbide endmill. Speeds and feeds were dead nuts, I had a fair chip, good coolant flow...AAAAAAAAAAAAAAAAAAA!!!!!!!!!!!

Now I have a $#@! endmill suitible only for a paper weight, and a jaw with a nice .03 radius in the corner... and a 008 taper from one end to the other...

Sigh..

Ok..I have a surface grinder and a life time supply of wheels, and it does track square with the rail I put on the back of the mag chuck....

Put the first jaw up against the rail, turn on the mag, and install a cup wheel, BACKWARDS, so its grinding benieth the spindle. Spray some dichem on the jaw, and go to town. Hum de dum...ok..looking good..hummmm the radius is much smaller, but its not a sharp corner... dress the wheel again.. smaller radius...but still not sharp...

Remove that jaw, and grind the other one..dress the wheel, grind, dress, grind, dress..still a small radius...

Retire for the night in a bit of frustration.

How the hell do you grind against a flat and get a sharp corner?

Somebody,,for the love of (insert deity of your choice) please help me!..sob..whimper..grovel....

Oh..I was using a pretty course white cup wheel. Im a bit short on harder cup wheels, but figuring that the jaws were harder than the hinges to Hell...

Today I dug around and got out a brand new diamond wheel that Id been hiding from the guys in the black helicopters...and very gingerly dressed up the jaws..but there is still a very small radius. Maybe .008.

At this point..Id use a dove tail cutter and undercut a bit..but those jaws are hard hard hard and figure Id simply burn up a cutter.

Any good ideas, hard and fast rules? Hints and kinks?

Gunner

"War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself."

- John Stewart Mill

Reply to
Gunner
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When I have a grinding job that just has to be right, the guy I send it to asks for an undercut, if at all possible. If not possible, a .010 radius is generally OK, but .020 or .030 makes him happier. Actually, I don't think anything I do makes him happy--make that less likely to piss and moan.

Ned Simmons

Reply to
Ned Simmons

If you have a steady hand, you might use a 1" dia cutoff wheel on a hand pencil grinder and undercut the corner slightly. The unreinforced wheels cut a pretty narrow kerf...

The spindle on my pencil grinder is sloppy enough as long as my hand doesn't contribute too much misdirection it'll track a preexisting groove or corner pretty well. I've held cuts to +/- .005 but it took a pretty fair bit of patience and good hand bracing. Groan.

If you don't want an undercut the fiberglass reinforced cutoff wheels could be dressed to 90deg but it might not be pretty.

StaticsJas> a bit of frustration.

degraded state of moral and patriotic feeling

nothing for which he is willing to fight,

miserable creature and has no chance of being

Reply to
Statics

I would grind the jaws with a flat wheel, just be prepared to dress the wheel alot if you want a small radius.

However I wouldn't have messed with the hard jaws in the first place. Just get some mild cold rolled or aluminum and make your custom jaws from that.

Reply to
Tony

I use flood coolant. I can get about 2 gallons a minute of oil on the work piece. I rigged the coolant system that came with my surface grinder to feed both the grinder and the big Gorton mill. But that's an interesting thought. I see a lot of carbide cutting metal every week, and this is the first time I've ever seen this particular thing happen. Hell, I've milled a bit of inconel without wiping out a cutter before. Weird shit Maynard.....

Excellent!!!!!!!!!!!! Idea. And after reading your post, I went out, put the jaws in my big B&S magnetic V block then put it on the mag chuck, installed a 6", 1/16th" cut off wheel, and did exactly that. Worked like a champ! And damn those jaws are hard. It took several passes to get an undercut of any depth, and those wheels go through

440 like a hot knife through a snow cone.

I was told this vise was a clone, but its made mighty darned well for a clone. No markings anywhere on it, so it may be a Kurt. The jaws at the least, were well made.

Thanks again to all of you whom responded!

Gunner, wannabe chip maker, and decent MT mechanic.

"War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling which thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself."

- John Stewart Mill

Reply to
Gunner

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