Diamond Grinding Wheels

Diamond is carbon and this can leech into the steel and affect its structure. However if you're grinding a carbide tipped tool you don't have much choice and I doubt it's much of an issue for home shop type people. I've tried my Cronos diamond wheel on steel but it runs very hot and as I don't have coolant set up I went back to a grit wheel. A sharp edged steel tool can strip away the diamond and ruin the wheel. Passing the wheel over a flat surface is better.
In general I'd say remove as much of the steel as you can with a grit wheel and use the diamond for the final pass where it's mainly grinding the carbide. For HSS tooling you don't need a diamond wheel so why risk using one?

Yes, yes, yes, yes
Nick

Its not for HSS specifically, more that I was going to get one for carbide, and remembered that I thought it was not good for steel, as confirmed by yourself and Nick, so no casual touchups, like I normally do with a diamond file. Ill normally be using a white alox wheel for most of the grinding anyway, guess Ill have to mount the diamond one when needed, and then swap back.
cheers
Dave

Or if you're feeling spendy you could get a CBN (cubic boron nitride) wheel - about £35 on fleabay.

Whats the advantage of CBN then?
Dave

You can use it on steel.
It's almost as hard as diamond and a) it's useable to higher temperatures and b) it doesn't leach into steel.
The few CBN tools I have used seem less brittle than diamond too, but that may be more the result of limited experience than usual practice.