Hand Tools Archive
I don't know what the "clearance wars" were, but it sounds like people were arguing that bevel-up planes have more wear on the back of the blade, and that this would cause clearance problems? I agree with you, David, that the wear on the back of a bevel-up blade is insignificant and is easily honed off during sharpening.
From the close-up images I've taken, it's clear that there's more wear on upper side of a plane blade than ton the lower side.
This is what the back of blade looks like after sharpening (Sigma 6000):
With a bevel-up plane, this is what it looks like after doing a significant amount of planing.
And with a bevel-down plane, this is what the back of the blade looks like after use:
Note that these blades were used in differently -- the bevel-up blade did more planing, but was also a more durable steel. Still, the difference is obvious.
For the bevel-up plane, the back wear is insignificant compared to the bevel-down plane, and I'm pretty sure that sharpening the bevel side will completely remove it. Now, these photos don't show the depth of the wear, but in the case of the bevel-down plane, it's worn enough that the horizontal scratches from the stone are gone -- it looks dark because the scratches are no longer there to reflect light.
The profile pictures from Steve Elliot's site show that at first, there's more wear on the upper side of the blade, but if you keep going and keep using the blade past the point where it's difficult to use, then it will develop significant wear on the bottom side.