Router Scarfing Jig
Boatbuilders often need to join boards end to end to make
longer planks. Instead of a butt joint they make a long taper
on each board and overlap the ends. This is called a scarf
joint. One or two scarf joints are easily planed by hand, but
for any quantity it’s well worth spending half an hour to
make this simple jig.
The illustration shows 3⁄4-in. stock being joined with a
slope of 8 to 1, which gives an overlap of 6 in. Position the
plank so the end to be joined is flush with the end of the jig
and wedge it securely. Make one pass with the router using a
straight-flute plunge bit to remove the bulk of material. Then
reset the router for a second, lighter cut, stopping just short
of a feather edge at the plank end. You may wish to clean up
the scarf with a few passes of a low-angle block plane.