There are many ways to clamp butt block
skarfs. (Scarfing is a fancy woodworking term used to
describe making two shorter pieces of wood into one longer piece.) You can use weights or short #6 sheet metal screws, or even clinch
bronze nails and leave them in place, but I prefer a staple gun with half inch
staples. The staples are removed after the joint cures.
Draw a center line down the butt
blocks. This line will be above the joint of the ply pieces. A large flat
surface is needed. It can be the floor or a table or workbench. I like to set up
saw horses with a sheet of ply or OSB on some 2x4s. Use wax paper or plastic
wrap to prevent gluing your pieces to the work surface.
a dry layout of the pieces and trim the butt blocks to clear the stem, chine
logs or inwales if you plan to install them. Trace the butt blocks during the
dry run. You can also round the edges and sand the blocks making them ready to
paint, before gluing them.
sure you weight or tack your pieces so they donít slide around when they have
the glue on them. Apply glue to the edges and the surfaces using your pencil trace lines as a guide. If you use PL Premium spread it with a notched trowel.
If you use Titebond II you can spread it with a brush, roller or spatula or
scrap of cardboard.
the butt blocks, drape twine over them and staple stradling the twine. A staple
every couple of inches will do. Make sure you get the corners. The twine both
prevents the 1/2Ē staples from going all the way through the ply and makes
removal easier. I usually let my joints dry overnight.
Here is a tip on this scarfing method.
I learned this trick while joining tops for musical instruments.
Slip a small strip of wood (say a 1/2" thick) under the joining edges to
hold them in a sort of tent position then clamp (or tack) both ends to your work
When that prop strip of wood is removed, and you flatten the
pressure gets transferred inward, to the edges of the glued pieces.
This is a rather unconventional approach to scarfing, however
if you read the fine essay by Jim
Michalak on various joining systems he's used you'll see he concludes that
all the systems have worked fine. He says:
"I've tried lots of different ways to make the joint in the 15 or so boats I've built
over the years. All the methods worked. I have a feeling that the butt joints on the
usual instant boat hull are not highly loaded and not too critical to overall boat
So it appears that the stresses on
these joints is not excessive. I've designed Summer Breeze so these joints occur
where the bending is very gradual. If you lack my faith in PL Premium feel free
to use any of the other approaches to joining wood outlined so well by Jim
Michalak and others. If you decide to use PL Premium, here are some tips.