Scarfing plywood tools

Use the glue lines in the plywood as a visual aid. Try to keep the glue lines straight and parallel as you remove the excess material. If the plywood glue lines become wavy, it is because there are humps and hollows. Use a straight edge to check flatness. Wear a dust mask if using a sander. The method described above is an excellent way to bevel several panels at once.

However, there are more efficient methods if you have many panels to cut. These involve specialty tools or fixtures to guide your power planes, circular saws or routers. Some of these fixtures you can build yourself. You attach the Scarffer to the base of a circular saw. It features a safety shroud that covers the blade. The Planer-Scarffer Attachment is another popular scarffing tool. Jig handle with the other. It does glide along smoothly. I put a handle on the above homemade scarfer this morning, waxed it up with furniture wax and cut some plywood.

The following panel is cut but not glued up. I'll do that glue it up tomorrow. This is to make a boat-shaped plug or form, not for making the actual boat. The home made scarfer pictured above made the smoothest scarfs I've ever made. Far better than the old metal factory made jig I bought from Gougeon Brothers 30 years ago.

The home made jig is larger and heavier and it doesn't shake vibrate or jiggle. Should'a done this a long time ago. I used to cut with the saw and factory made jig and then I had to clean the scarf up with an extra sharp hand plane, prior to gluing. No need for that now. This will glue up just fine. Right off the home made saw jig. I may want to use these temporary form panels for years to come.

So--even though it's just a form--I'll probably glass up one side of the panel first, prior to cutting it up into two side panels. And then work with trial and error until I get a good-looking boat shape. That process is hard on temporary side panels made from cheap construction plywood.

If you have any unevenness on the scarf joint be sure to sand the surface with a hard and flat sanding block. The plane will lose its fine cutting edge quickly when you plane plywood due to the adhesive between plies. The lines created by the various plies in the plywood give a good indication of progress you are making when creating the bevel. Any humps or unevenness in the bevel usually show up as a crooked line when you sight down the glue line between the laminations.

You can save a good deal of time when hand beveling by setting up several panels in a stack for simultaneous block planing. Scarfing wood together dates back ages. Scarfing is the process of cutting corresponding angles or sometimes shapes on two similar pieces of wood and gluing them together to create a larger piece of lumber or plywood.

The most common place scarfing is used is in building a stitch-and-glue canoe or kayak. I had plans to build two kayaks over the winter, with five scarfs on each hull. The Scarffer is an excellent tool for cutting the 8-to-1 scarf needed for plywood. Like any new woodworking tool, there is a little setup time required.

You will need to drill holes in the baseplate of your circular saw. Check the alignment of the holes on the base plate before drilling.