"Tim Douglass" wrote in message
...
On Sun, 3 Oct 2004 18:57:09 -0500, "Todd Fatheree"
wrote:

However people confuse ejection for kickback,
where kickback is generally far more dangerous. Ejection occurs when the
workpiece is ejected straight back due to the friction force between the
workpiece and the saw blade. Per Kelly Mehler in _The Table Saw Book_,
"kickback is caused by the tendency of the rising teeth at the rear of
the
blade to pick up the workpiece, catapulting it toward the operator at
speeds
approaching 100 miles per hour." When this happens "the workpiece is
hurtled diagonally backward toward the operator." If you're standing to
the
left of the blade, you're going to catch a kickback right in the gut.

I have never seen or heard of a saw actually kicking a piece in any
direction other than in line with the blade.

Then you've never witnessed kickback. I have. Count yourself lucky.
Fortunately for me, when I witnessed it, someone else was driving. Not
including the kickback demonstration Mr. Mehler did at a woodworking show I
attended a couple of years back.

Based on physics, I can
see a potential for the piece to perhaps move somewhat to one side or
the other depending on weight and contact with the fence, but for it
to be thrown so that it will hit an operator to the side seems
questionable.

Consider: The piece gets caught on the teeth at the back of the saw
and the back edge of the piece rises, for all intents and purposes the
force acting on the wood is tangent to the circle of the saw blade.
The saw cannot exert any force to either side so I would assume that
the piece will rise from the table and the leading end will be kicked
upward and back in line with the blade. The piece will only travel
diagonally in the sense that it is moving up and back from the saw,
toward where an operator in-line with the blade will be standing.

This would probably be true if the fence was not in the way. However, its
presence creates different forces than just the force of the blade against
the wood as the piece binds against the fence. If you were correct, the
mark the blade left in the workpiece in a true kickback would be a straight
line. However, many people that have had the misfortune to experience it
can show you a workpiece with a nice arc cut into it as the piece was shot
out diagonally.

todd