Sharpening 5% cobalt

Just bought some blank bits for a small boring bar. Says 5% Cobalt on the side, 1/8" What do I need to sharpen this - will my regular gray grinding wheels do it? Also have a small diamond wheel that might fit a Dremel.

Reply to
Rex B
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A gray grinding wheel is really too hard for grinding HSS, but you don't have much to remove with bits so small. Make sure your wheel isn't glazed (use a dressing stone or a star wheel but don't tell Harold) and don't let it load up on ya. Watch your temperature. 1/8" bits are easy, only take a few seconds.

GWE

Reply to
Grant Erwin

They should -- I've done so -- though some others might be better.

Proably not that good an idea. Cobalt HSS has steel, and steel absorbs carbon from the diamonds so you will burn up the wheel working on this. Diamond is good for sharpening carbides, but not so for steels, including cobalt HSS.

Enjoy, DoN.

Reply to
DoN. Nichols

:^)

:^)

:^)

Jim

Reply to
jim rozen

Did not know that, thanks

Reply to
Rex B

Reply to
machineman

We sharpen 10% cobalt lathes tools from 1/8 sq through 3/8 square from time to time using the regular AlOx [white] wheel with no problems. We seem to get better results from the fine grit wheel

Be sure the face of the wheel is dressed/clean, take your time, and avoid overheating the tool. You can dip to tool in water while you are grinding to cool it off as long as it dosent get too hot. If the tool is real hot, and makes a hiss when you put it in the water you run the risk of thermal cracking and early failure.

We have found that if you will recycle a windex type spray bottle and mist the wheel you can keep the tool much cooler while grinding. Also, avoid breathing any of the dust. Cobalt dust is listed as a hazardous material [do a google search on >cobalt grinding msds< for more info]

Reply to
F. George McDuffee

I like! Another neat trick filed away for future reference!

While a little OT, I use the same spray bottles with alcohol for aluminium samples (for chemical testing) turned on a lathe as a coolant. This prevents the tip "welding" itself to the job and it's surprising how little is needed from a spray bottle to produce a really clean cut on a wide range of aluminium alloys. Between the coolant and the flash triangular lathe tips that can be interchanged and turned three times, you can get an almost mirror finish with slow feed and fine cuts.

Hope this helps, Peter

p.s. Don't try this at home with your smoke hanging out the side of your mouth!

Reply to
Bushy Pete

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