One question, Why do you want to keep the blade edge straight? Much too much grinding with no improvement in cutting. As the blade wears, the tip gets the most wear. Grinding the blade edge straight to match the tip width is not required. The reason I say this is because I have built a couple of blade grinders and one of them was set up to do as you say. Took forever to sharpen with no appreciable cutting quality. The machinist's vise moves slowly and you MIGHT have trouble not over heating your blade. Typically a machinist will have a cooling agent running over the stock being machined.
I sharpened blades on a lathe. Took forever and it was the same principle as what you are talking about. Then I converted a big radial arm saw, again the same principal, the stone would slide back an forth on the edge of the blade and it took forever to sharpen.
My best sharpener is a belt sander I built form scratch with an adjustable blade rest. I use a 36 grit belt two inches wide and 72 inches long. 1 hp motor at 3475. One minute a blade. I have a wire brush mounted on the belt sander also too facilitate cleaning the build-up of before sharpening. Total cost was somewhere around $250.00 and it will sharpen any type of blade and is useful for many other things. I have used all the commercial blade grinders and the belt sander is much better, IN MY OPINION!