On 18 Sep 2006 09:40:22 -0700, stryped wrote:

I layed a metal square on the table and could see light under the
middle. Did not use a guage to see how much.

What is the best way to determin if the table needs reground and how to
measure it?

Can any metal rule be used as a straight edge?

Only if its edge is straight.

Better to use an instrument built for the purpose. A 24" aluminum
straightedge, probably just about long enough to check your jointer tables,
can be purchased for around $25. Still, that's money that could be used for
something more useful, especially if you can borrow a proper straightedge for
the few minutes it will take to properly evaluate those tables.

--
Art Greenberg
artg at eclipse dot net