At 6:51 PM -0400 12/3/99, David wrote:
>Ahh, but the analysis is faulty for another reason.  The surface of the wood
>ahead of the iron is going to be higher than the suface of the wood behind
>the iron.
        [more snippage]
the board is not actually arced, it is two flat planes
>offset by the depth of the cut.

        Ain't gonna get into the math(s), because I can barely do enough
cipherin' to balance my checkbook.  BUT, I have a, um, practical question
prompted by David's seemingly logical comments on these arcane matters.
I've thought about it when these issues have come up before, as when
discussing the difference between removing wood with a p*w*r jointer vs. a
hand plane.  But I can't let it pass this time.
        The standard bench plane configuration, as I contemplate it, is a
(nominally) flat surface or sort of platform with the cutting edge of the
iron protruding from it. Again speaking "nominally," the plane won't cut
unless the cutting edge protrudes from the (nominally) flat sole. I would
like to focus our attention on those little strips of the sole that flank
the cutting edge in either side, preventing the body of the plane from
falling into a lower *plane* behind the cut than in front of the cut.
        If I'm right about this, then all surfacing is like a delicate
version of a scrub, in which the shaving is a slice of wood scalloped out
from between those little strips of sole on each side of the mouth.
        I started thinking about the process in this way when I once
grabbed my Stanley #10 1/2, a rabbet plane in which the cutting edge of the
iron extends through openings in the cheeks clear to the edge of the sole,
and tried to plane a flat surface with it.  It is ground as straight across
as I can make it, no radius, which is essential for a rabbet plane.  It
grabbed.  I backed off the iron.  It grabbed.  I backed off some more.  It
didn't cut.  A #3 smoother with a straight-across edge will take a
U-section shaving off, but its sole will slide along supported on both
sides of the cutting edge by those little runner-like pieces of sole on
each side of the mouth.
        So maybe a bench plane *needs* to be a sort of a platform or
4-sided frame with a slot through which the cutting iron protrudes.  And
maybe a board, after a plane has made a cut, is still (nominally) flat,
with a very shallow gouge down the path where the plane passed.
        Of course, I don't think much of this arcane speculation has much
to do with dimensioning and smoothing wood in the real world, but since
BugBear decided to get theoretical on us, I thought about my experience
trying to plane a flat surface with a rabbet plane, and decided to join the
fun.
        Am I crazy, or just silly?
                Tom Holloway