"Kevin L. Bowling" writes:

I didn't even know what a scarf joint was. Had to do an internet search.
Apparently used in boat building to join two or more sheets of plywwood
lengthwise. Supposed to use at least an 8:1 ratio. You could do a butt
joint
using a small piece of wood glued to the back and have as much gluing
surface as you want.

No, not quite.

A butt joint made with a backing block would, as you suggest, provide more
than enough strength compared to a scarf joint; however, it would also
provide a "hard spot" that would not provide a continuous curve when bent,
which is why scarf joints are usually used.

Whether you use a scarf joint in a piece of crown molding is no big deal,
especially if you set up a jig for either a router of a hand power planer.

I have a couple of scarfing jigs made from nothing more than 3/4" plywood.

One advantage of a scarf is that it allows you to recover short pieces of
expensive material to make longer pieces.

(Ever try to find some 60 ft long pieces of clear Doug Fir for a boat mast
lately?)G.

HTH


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures