On Thu, 17 Jun 2010 09:23:22 -0700 (PDT), Andy Dingley
wrote:

a half-lapped edge is better. Your boards
should only be fastened in the centre of the board, so that their
edges can move in and out freely. The half-lap stops a gap appearing.
You can buy timber machined like this, saw it on your table saw
(best), hand plane it with a #78 or rebate with a router.

Thanks. I'm wondering why using the table saw is best rather than a
router? Wouldn't you have to make two passes with a table saw but only
one with a router?

Is there a reason to use half lap joints rather than saw the edges at
45 degrees? Wouldn't that allow for expansion without creating gaps to
see through?

TIA