Drill bit web thinning.

[tonyfoale]

I find that the fixed attitude of the grinder angle does not match well to the factory grind of many chains.
........ My grinder spins at 6500 RPM hence is why I use only the 10,00 RPM or better disks

I had no trouble with the angles nor sharpening the chains, but I do find it faster to do with a file. My needs are minimal, if I have to do a chain once a year that would be a lot.
I misunderstood your previous post. I read it as if your grinder spun at 10,000 rpm, now I see that you buy only buy 10,000 rated disks.