Get your primary bevel down to where the cutting edge is .020" or less to start.
I am sure you are not sharpening a blade before heat treat, correct.
I have never tried to get my final cutting edge using a belt sander.
With a new blade I rough shape the cutting bevel (to save stones) with a 1x42 using 120 grit.
I sharpened blades for 40+ years using 12" bench stones and thought I was doing pretty good until
Boise lent me his Edge Pro. Then I learned what scarry sharp really was.
I use a Work Sharp for my filet and kitchen knives. It gives you a slightly convex edge.
Basic unit is about $80.
It works fairly well, but I go to the fixture system with my custom knives.
If you are going to stick with the 2x72 to get your cutting edge, I suggest you do not try to get a
flat bevel for the cutting edge bevel. I would go for a convex cutting bevel. That would require you
to push the blade edge against the belt in a free span area vs against the flat platen.
I would check for a burr before going to a finer grit.
I would think that 600 to 800 grit would be a good place to stop.
Then strop lightly on a piece of leather impregnated with some mild abrasive.
I use Semi Chrome, but I have heard of people using tooth paste or the slurry of scarf from a fine bench stone.
25 degrees is quite steep. Some where around 20 should be a good place for now.
With the Edge Pro I am going to 18 degrees now, and get a very uniform edge.
With the Work Sharp, I normally use the 20 degree fixture.
You do have to make mistakes along the way, so do not get depressed. Knife makers do not make mistakes, they
just are making a new proto type.
