"Allen" wrote in message
m...
These guys (www.collinstool.com/collins_ply_prep.htm) sell a router
bit to put a concave edge on plywood in preparation for edging. They
claim that some of the inner plys swell when glued and cause a small
open seam between the edging and the face plys. Seems to make sense,
but what is the opinion of the group?

Thanks, all.

Allen

In principle these guys are correct, both solid wood and ply will swell with
the application of glue, or most liquids. It is one of the reasons that
joints should not be machined before they are fully dry, otherwise there
will be a small depression which can be seen if a high gloss coat is later
applied.

In practice, unless you are running a large operation where you machine all
parts to high tolerance before gluing, you will need to do a clean up after
the parts are dried and you probably won't notice the difference.

Bernard R