Hello Bernard
The center hole is accurate as in concentric,you may have to turn up a bush to fit whatever spindle you use whether a bench grinder or a tool cutter grinder.
I have several different shape wheels as I also sharpen my Mills Taps
Chisels Knives punches and any thing else.
I never found they run out of true.I think one vibrates a little but did not effect the sharpening.
I have used mine for over 5 years with no sign of wear, nearly all my lathe tools are carbide.
I also have a number of carbide drills and they are sharpened with the diamond wheel.
At times I have chipped a drill or lathe tool and ground back to shape so 2mm is not a lot and does not seem to wear the wheel.
I grind at high speed and dry.
Don't let the tool get to hot and don't quench as it may cause hair cracks.
As for Green stone! never again for me I could never get the edge I required.
Regards
Trev
