I've been offered a surface grinder

[TomG]

Darren,

I think I posted some info on wheel grades a while back, but I can't remember where.

That knurl pattern you were wondering about is caused by one knurl having more pressure on it than the other, which results in one diamond pattern being deeper than the other. The clamp knurling tool I'm currently making all but eliminates that problem and also helps prevent double knurls.

Tom