Making precision machinists squares from scrap of metal

[Karl_H]

I don’t understand the mechanics of a surface grinder. How do you avoid a rising surface owing to the gradual wear of the grinding disc?

In addition to the light cuts, you are really only cutting with the very first part of the wheel to contact the piece. As that part wears down, the cutting surface of the wheel moves over to "fresh" wheel. So now, the leading edge of the wheel is cutting the first 1/2 tenth and the "fresh" part of the wheel only has the cut the second 1/2 tenth.

In the video, from 9:05 to 9:20 you can see that the portion of the wheel closest to the machine is doing the cutting, and that there are no sparks forming on the surface closest to the viewer.