I am finally getting some time back at the workbench and finishing up some knives that I had started a while back. Maybe I lost my touch or something, but I can't seem to get the vee grind true flat. I think I am rocking a bit, making it more of a very slight dome (convex) shape (if that makes sense to you). Visually it looks fine but if you put a straightedge on it you can tell.

Big deal or not?

Any hints on fixing/preventing this? I don't know if it is coming off the belt grinder this way or if I am doing it when I hit it with the wet sandpaper to smooth/polish it out...but I suspect a little of both. The perfectionist in me doesn't like it now that I know it is there...

Are you talking about the edge bevel?

No, I am talking about the flat side of the blade when grinding it from barstock...before heat treating, adding handle, etc.

So you are doing a flat grind as opposed to a hollow grind.
I've found that using the platen on my grinder will leave the surface rounded due to belt deflection. If you watch the belt while you're grinding, you'll see it bow inward as the blade pushes on it while grinding. I don't know of a way to pervent this as you'll always have some belt deflection. It would take a long time to make the sides perfectly flat by hand.
If you can live with the slight convex sides, that's what I would do. As long as the blade is heat treated right, the important thing is getting it sharpened with a good edge, where the edge bevel is perfectly flat on each side; very important to a sharp edge that will last.

I'm not set up with a contact wheel for hollow grinding, so yes, I am doing a flat (as I can achieve) grind.

Your answer made me wonder if I should try to slightly curve my platen to compensate??? I don't know if I could do it well, but I'm just crazy enough to give it a try.

Thanks!

I suspect you're rocking the blade. Perhaps pushing too hard to get material off quickly.

Make sure the belt is sharp and clean.

Cleanup the working blades with sandpaper on an oak or hickory 1 x 2" block. Start with 120 ... sand across, at 45 degrees both ways, and down the blade. Use a good lubricating cutting fluid and don't let the "mud" accumulate too much at the coarse levels. Move to 180, then 240 or 320. HT and go back to 180 and do 240/320, 400, 600, 1200, and 2000 for a matt finish. Use an soft block for the 1200 and 2000 to get an even matt.

I may have let the belt get worn, but the hand work is basically what I am doing...though I don't know what you mean by 'good' lubricant. I use plain water (I figured that petroleum cutting fluids would be incompatible with wet sanding paper) with a tiny bit of soap for better wetting.

I can't push too hard or I'll stall the weak motor my cheap belt grinder wears... though the rocking is a distinct possibility and one I had considered. I guess the cure for that is just practice and experience, or are there tricks I should know. I try to 'lock' my elbows and sort of 'slide with my waist' to keep the knife pretty well stable...

I use Cool Tool II which is certified for use on food handling equipment by the FDA. Works great! Is available from MSC. Wipe off with paper towel though ... you can' get it out of rags easily by washing.

Final grits of matt finish should be done dry.