: I haven't seen anything in the archives about using a half lap joint on
: 1/4"x3/4" strips. Is there a reason for this? After building a
: scarf jig for my router and one for my table saw, I wasn't real happy with
: either. I ended up with a 2" half lap that I am happy with, using
: dado table saw blades. It looks like this would be a stronger joint since
: the end grains wouldn't be glued together as a scarf joint would. I will
: use this half lap joint only on my long starter strips for the sheer and
: the rest will be butt joints, I think.

: John

The process of joining two pieces end to end to make a longer piece is often referred to as scarfing -- and there are several joints used for this. Half-lap joints are one style used. Another style commony used is a long diagonal joint. Ofentimes we refer to this diagonal joint (and this alone) as a "scarf joint". In doing so we may be making a semantic distinction which is not always correct.

Pictures I have seen of scarfing of bone and driftwood, as used in the early crafts of indigenous peoples, are rarely a long diagonal joint. They seemed to favor a joint where the parts interlinked. In the absense of the strong adhesives which we have available today such a joint made sense as it could be wrapped on the outside with sinew or wet rawhide, which would shrink while drying, and hold the pieces firmly. I believe one maker of kayak kits (I think it is Pygmy --someone will certainly correct me if i am wrong ) uses a similar profile on the scarf joints they make on the plywood panels for their stitch and glue kits. It helps aling things while the glue sets up.

For creating the few full length strips you would need for starter strips a half-lap joint is ideal. It is simple and frequently overlooked by many builders.

I think the big reason most texts and home builders concentrate on the long, diagonal scarf joint is that it can be formed easily without power tools. Stack your two strips on your workbench and a few strokes with a plane does the trick. The soft cedar is easily and rapidly shaped. Tolerances can be rather loose as the exact angle is not important. As long as the angles for both pieces match, or come close, you can draw the wood together with some clamp pressure to get a neat joint.

The diagonal scarf joint is also a bit faster to set up if you are just doing several, but on different thicknesses of stock, as you can make a variety of jigs that work with several different types of power tools. As long as you establish the angle of the scarf, you cna make your jig as long as you want so it can hadle thicker materials. So, you make one setup and you can scarf 3/4 inch chines, or 4 mm panels, 1/4 inch strips or maybe 2x4s.

With a half-lap joint you need to spend a (very few) minutes setting up the cut on a tablesaw or router. The setup changes with the difference in thickness of the various pieces. If you have the dado head, then you are nearly home free. Set the depth and length and go to it. Once the wood is cut the parts line up easily and are easy to clamp while the glue sets.

Hint: You should trim about 1/4 inch off of the ends of each strip before you make the half-lap joint cuts. The ends of the wood discolor a bit with age, and the end grain is rougher. The difference makes the joint more noticeable. Trim off the ends and the joint is less noticeable. Usually in cutting a diagonal scarf the very end is cut away, so this problem is not so noticeable.

If you are all set up to do dados, and you forget to knock the end off of the strip, just let the dado cutter remove some stock form the end, then flip it and the dado will remove the rest from the other side. Spend time setting up your alignment and you will save much more time in sanding later on.

have fun.

PGJ