Jerry Hobson wrote:
The question I have, is he right?
It seems like an easy and cheap method for joining boards if you keep them under
planner width.

It depends on the type of joint:

For edge-joining boards along the grain:
Yes. The glue gives an edge-joint its strength. The biscuits add a little
and dowels even less. Primarily they provide alignment. I use my plate
joiner all the time, but for alignment, not strength. Except in extraordinary
usage, if the joint fails, biscuits would not have helped. In this case, the
nails simply keep the joint from shifting while the glue dries (a la Norm).

For end-to-edge joining boards (such as a rail-to-stile joint in a door):
Probably not. The biscuit offers significant benefit here. Becaue the glue
joint is end-grain to long-grain, the glue-joint strength is MUCH lower.
The tenon, be it a traditional tenon, floating tenon, biscuit, dowel or nail
is providing a significant amount of the strength against 'racking' of the
joint (twisting force). The nails will not provide much strength here,
especially in soft wood like cedar, since they offer little resitance to
pulling them back out.

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Chris Merrill

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