In a message dated 12/3/99 8:16:48 AM Eastern Standard Time,
bugbear@c... writes:

<< To those of you who hate analysis, engineering and
 especially maths, but prefer honest sweat and shavings,
 I say: Move along, nothing to see here.

 Hmmm. Gone kinda quiet. Anyway...


  >>
Ahh, but the analysis is faulty for another reason.  The surface of the wodd
ahaed of the iron is coing to be higher than the suface of the wood behind
the iron.

Let's make some unrealistic assumptions.
1.   the sole of the plane is perfectly flat.
2.   the board is perfectly straight.

If the iron is set at .05mm (that's a hypothetical example equal to .002",
everyone but Jeff), and the cut starts with the sole from the toe to the iron
flat on the board, then the cut starts at .05mm deep.  According to Paul's
figuring, by the time the heel is over the board, the plane will be cutting a
concave arc.  However, if the shaving stays at .05mm, and it can't become
greater than that, then there are three points on the board that are at the
toe, the iron and the heel that describe an arc.  This arc is the exact same
radius as the one that Paul calculated, but it is convex instead of concave.
Keep in mind that the board is not actually arced, it is two flat planes
offset by the depth of the cut.  This counters the tendancy to make an arc if
the cut was started in the middle of the board.  Therefore, it is extremely
feasable to plane a board and make it flat.

David

who is getting called away to light candles