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CBN Wheels

D

Downwindtracker2

Ultra Member
I had changed my 7" bench grinder over to CBN wheels , a 80grit and a 320grit . I just ground a 55* Whitworth threading bit. I was going to rough it out on the bench grinder and finish up on my Toolmaker surface grinder. I hit the point, bang on according to thread gauge. After the hours of struggle in college grinding tool bits, it was very quick and easy . I only had to cool the 5/16 Cobalt HSS blank twice. I just used the 80grit. WOW
 
Lee Valley carries them as does Woodturners Wonders.
They are very popular with wood turners because the diameter does not change with use so jigs used to put complex shapes on a tool can be set and never touched.
 
Since my 1/2 hp Wissota grinder is 7", Baltic Abrasives made them for me. Great service. My wife's Rock and Gem club uses their diamond lapidary wheels. They never need dressing. But they are heavy requiring a good grinder. They also spin forever.
 
How well do they work on regular high carbon steel like chisels? I gather that they can get contaminated on mild steel. How low can the carbon go before it is an issue?

Brian
 
All my research says that anything less than 45 Rockwell C hardness is no bueno for CBN.
More than .50% carbon is good to go. But I would not grind cast iron.

From the web
"CBN can be used on steel, its diamond that shouldnt be. With diamond, the carbon from the diamond can actually migrate into the steel under grinding heat and pressure, which destroys the wheel in pretty short order. CBN doesnt have the same issue, in fact its actually made for grinding hardened steels, carbon steel included

What you do have to watch out for is soft materials, though bear in mind that means soft as far as metals go, not soft as a general term. Soft materials can smear into the wheel, clogs up the abrasives and prevents the abrasive from actually working. Stay away from anything non-ferrous, i.e not steel. Mild steel is probably safe, though personally id avoid it. Plenty of other options for mild steel, keep the fancy stuff for hardened tool steels"
 
I found wood chisels and plane irons are best reshaped on a belt sander. I use a Veil 1"x42" that Lee Valley sells. I use a reversible 1/4hp motor. on it. I made up a jig for that. But when I want a quick edge, I use a 1000grit belt followed by a hard felt strop with Lee Valleys green crayon. But normally I use ceramic waterstones.

Wood turners use HSS chisels. Even the cheap ones say they are HSS.
 
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