Subject: Re: Green Wheel Grinders

From: Steve Wellcome <[email-masked]>
Date: 13 Sep 1996 15:25:42 GMT

I use a "green wheel" to grind HSS all the time.  I think it
works better than regular wheels.  It wears down faster than
the wheels you're "supposed" to use for HSS, but I find I
have less of a heating problem.

N.b according to several books I've read, you can't get a
truly sharp edge on carbide with a green wheel. No matter
what you do, the edge will have small cracks and chips when
sharpened on a green wheel.  It will seem to be sharp, it
will work, but if you look at the edge under a 10X magnifier
you'll see chips.  To get a really good edge on
carbide, you need a diamond wheel (which you have). So use 
the green wheel for roughing carbide, and finish on the
diamond.  

Another caution: if you sharpen HSS on the diamond wheel,
use water.  Carbon dissolves into steel at high temperatures,
and guess what a diamond is made of?  And the local 
temperature right at the point of grinding can get plenty
hot enough to dissolve the diamond into the steel.  So
use water.

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From: [email-masked] (Felice Luftschein & Nicholas Carter)
Date: Fri, 13 Sep 1996 16:36:43 GMT

In article <[email-masked]> Steve Wellcome 
<[email-masked]> writes:>Another caution: if you sharpen HSS on 
the diamond wheel,>use water.  Carbon dissolves into steel at high 
temperatures,>and guess what a diamond is made of?  And the local 
>hot enough to dissolve the diamond into the steel.  So

I can't comment on the idea that diamond dissolves into steel, although
I think that may not be true. The reason I use water/coolant on my diamond 
wheels is that I've heard carbide dust is toxic, as is stone dust which I 
grind frequently. Also, the bond can contain nickel which becomes dust if it
is rubbed off, also carcinogenic. The heat of grinding dry (except on a dry 
wheel) can cause electroplated backings to separate from the wheel, and loosen
their hold on the diamonds. This does not apply to resinoid or sintered wheels 
though. just my 2 cents.