On 8/20/2013 8:57 PM, Leon wrote:

;~) Well hopefully your fence is not square to the slot, it should be
parallel. But that is probably what you meant.

What condition is your saw in? Could worn bearings be a possibility.

Secondly you mention that the edge is concave, is that bowed along its
length or is the middle of the cut deeper than the top and bottom sides
of the material?

Are you using a think kerf blade? If it is a very likely culprit
especially if it is not sharp.

Are you buying quality lumber? Case hardened wood will bow after being
cut although this does not explain the problem with plywood.

My first guess is that you are using a think kerf blade and that is
giving you problems.

I thought I knew a little about saws but then saw your reference to a
"think kerf blade" What is it.