I usually do not buy new lap equipment. I have looked at them at R&M shows, and they have that distinct made in China look, which on the surface appear to be of limited in lifespan, etc. I buy older, Raytech, StarDiamond, Frampton, Poly, and others. I buy them from estate and other sales where folks just want to unload everything, blades, wheels, polishes, and slabs. Ultimately comes out way cheaper, although I always seem to get one or two Carborundum wheels in the mix. (I also have four almost new expansion drums of 6&8" variety which were "throw ins" as well. Oh well)
I have my own diamond wheels and soft wheels, which I use for cabbing, so I am getting quite a few Carb wheels stacking up in my shop. I buy those Rez soft wheels from Baltic abrasive which require breaking in. I have a chunk of opalized agate which I use to break in the new wheels when I get them. Rez wheels seem to last longer, and the guy at Baltic Abrasives stands behind his equipment.
My point is that the "break-in" agate I use is pretty rugged. I have been grinding / smoothing it on the "C" wheels to knock off the edges etc . Occasionally I have used them to "rough out" pre-forms. Some of these old C wheels are in
bad shape with grooves, channels, etc. Other than taking off the rough edge stuff, I never really use them much because of the shape they are in, and I am not sure if C wheels leave more gouges and scratches,
There has been much discussion about old diamond wheels, -- refurbishing, etc. Does anyone use these old Carborundum wheels for any reasons not mentioned here?