On Sun, 1 Aug 2004 13:07:05 -0500, "RonB" wrote:

(Also Posted in abpw)

I would like to run this past the group. For years we have been told that
the best way to glue up slabs, like table tops, was to alternate the
direction of growth rings using 4"-5" boards. Occasionally this caused us
to rip and join a perfectly good 18" to 24" slab of hardwood and end up with
a slab with discontinuous grain pattern -- necessary for the integrity of
the slab.

A couple of years ago I was building a 8/4 Oak table top for a coffee table
and was unsure of the best rip widths for the glue-up assembly with this
heavy material. I posted to forums of a couple of woodworking magazines and
was surprised at a response. A magazine editor said that with heavy stock,
with fairly large radius growth rings, it was ok to rip at 4" to 5" and glue
them back together in their original position. He claimed the glue joints
did an adequate job of relieving the stress and I could retain the original
appearance of the slab.

The post came slowly -- after I had ripped and glued in the conventional
(alternating) manner. The top looked fine but I still
wonder.............????

ANY INPUT?

Disclaimer: I really (really) am no expert, I'm just giving my
input...

Say you rip the slab with a glue-line rip blade and the pieces don't
need rejointing when you are done - there has been zero movement. It
seems to me that with regard to internal stresses existing in the
wood, you've either done nothing to relieve them or they didn't exist
in the first place. Then you reglue the pieces back together, and
you've lost a few kerf-widths of wood. I'm not sure you've
accomplished anything. Does the fact that wood glue is stronger than
the wood itself make the slab stronger as a whole? Maybe very, very
slightly. If the pieces needed significant rejointing, my guess is
that you have probably increased the structural integrity of the
board.

However, it's my understanding that the reason you alternate flipping
the boards over is to create an alternating warp pattern. Rather than
risking the whole board being in one big cup, you end up with a series
of little up and down cups across the width of the panel that tend to
even each other out.

JP
*********
Warped.