Thin Stock Wavey Bevel

Several pass at end of grinding with light pressure , high belt speed and uniform motion of blade cross belt , works for me .This is done that way with 40 grit belt ............

 

Yup.
The thin material deflects while you're grinding from heat, stress, and pressure. And again then later during quench.
Also, the angles are much steeper on thicker stock, and easier to feel, for me anyway.
That particular wave above is pretty minor. For a saber grind on thin stock, I'd correct that with a sanding block, elbow grease, and profanity. But then it would be hand-finished...

 

I'll be watching this closely. The issue is the small angle difference between the bevel and flat that compounds waves.

I find it helps to use a rest so you can focus on pressure against the belt. I place my left thumb behind the blade and draw the knife across the edge of the belt. I keep the blade angled very slightly off the belt. I'll also put my thumb right on the spot where I need to raise the grind line. As my thumb approaches the edge of the belt I start to apply a little more pressure with my thumb and then ease off once past. Very light pressure an sneak up on it. Of course a sharp belt is a must. Unlike above, I try to use very slow speed when getting close as I'm afraid I'll approach the belt at the wrong angle and dig a groove.

Once I screw up it use the slack belt and convex it or do a FFG . I find it very difficult to get straight lines on kitchen knives so you're not alone.

 

Yeah and the stock might have a lateral curve from grinding. It might help to switch grinding sides more frequently.

 

On thin stock blades (kitchen, filet blades ect) i clamp a piece of thick stock on the side im not grinding. Stops it from flexing and causing grind line issues.