Is the tru-grit disk aluminum? (Honestly, I do not know) If it is steel, then why not go with that for your needs of a steel disk? Apparently, the Beaumont Metal Works disk is aluminum. I didn't realize this in my original reply.
I own the Nielsen disk system and am completely satisfied with it although it is a bit pricey and because I am not worried about 0.002" surface flatness or rotational run-out after easily slapping a different grit disk onto the magnetic hub. It does a great job of flattening handle tangs and scales and allows for easy grit progression.
As Karl stated, he is simply seeking a steel disk. I guess that he grinds a lot on the edge of the disk and aluminum is not quite up to the task?
I can't imagine that any machine shop which supplies disks to the various knife making suppliers are not aware that it is best to machine the bore, face, and OD in one set-up . . . it's not rocket science to machine it true whether it is steel or aluminum. Since these are intended to install onto a motor shaft, there are tight tolerances already generally established for the fitment over motor shafts and most shops wouldn't simply drill the hole with a drill bit. It's generally understood that the bore must be turned with a tool rather than drilled with a bit. Properly annotated detail drawings with geometric tolerances can force these requirements upon the supplying machine shop, as well.
Machining hardened steel to such a thin profile is a different story, but I argue why that is even necessary due to the economics. Yes, I would like a very hard plate which will last a long time, but . . .
By the way, no one . . . can machine with
zero run-out. There's always an allowable tolerance.
I think disk grinder systems are over-discussed.
Mike L.
