I came to this razor hobby from my knife hobby. Not knowing any better I’ve been using a belt grinder to sharpen dull razors, and it seems to work well for me. The time commitment is certainly less than that required for a manual sharpening.

I use care not to heat the blade and destroy the temper. Also, I sharpen so the belt runs from the spine of the blade towards the edge, as is done in stropping. That way the edge will not catch on the belt as it would if I let the belt run towards the sharp edge. It goes without saying that complete attention is required, as razor + power tool is a potentially dangerous combination. I usually use a supported section of the belt, to avoid convexing the edge.

If there are large nicks in the blade I take them out with a 20 micron belt. This process is pretty sure to leave a wire edge on the blade, so I break that off with slicing through some cardboard.

Then I go down to a 9 micron belt. If there were no big nicks to grind down I can just start with the 9 micron. I use a light hand here to avoid the wire edge. If one develops I break it off with the cardboard. Next I use a leather belt on the grinder with green chrome compound. After that the razor is ready for a light honing on the Swaty and a shave.

There was no magic to the abrasive grits I’m using. They were what I had and they work. Some finer grit belts may be available if someone should desire an even finer edge.