: ANY THOUGHTS ON USING A WIDER KERF (1/8") AND WHAT WOULD BE IDEAL SPLINE
: STOCK,

The plywood is either 3mm or 4mm thick in total. With 25.4 mm to an inch you have 3mm plywood coming in at just under 1/8th of an inch thick. A 1/8th inch kerf would be bigger than the thickness of the 3mm plywood, and it would simply turn your "joint" to a pile of sawdust. If youwere working with 4mm plywood, then by very careful centering you could remove 1/8th inch of material from the center of the plywood, but you would be left with a front and rear veneer face that was so thin as to have negligible structural strength.

As Ted Henry's pictures show, a 1/16th kerf eats out the center layer-- which is just under 2mm thick -- and leaves the full thickness of each of the face veneers.

While the wood that you remove has the grain going at right angles to the grain on the face veneers, you would not want to use a spline that had the same orientation as the center veneer. If you did, your joint could fail with jsut gentl flexing of the joined plywood sheets, as the spline would split along a grain line (which would be parallel to the edges of the joint). Your options therefore are to make splines with the grain running in the same direction as the face grain, or to make splines that had grain running at an angle -- say 30 to 60 degrees of the angle of the face grain.

ass for stock for the splines, you could use scraps from your 4mm plywood, if you have any. Either use a saw to remove the face veneers from your scraps, leaving the center core -- which should be the right thickness. Or use your saw or power planer to cut through the plywood and reduce it to the desired thickness. If you do this you'll have a spline that is made of two plies. One will be the outer veneer and the other will be a thinned center ply. This can be used at almost any angle or alignment as a spline. If you have no scraps of your particular boat plywood, you can use any other plywood scraps, or solid wood stock that you might wish to reduce to size. If you are working with solid stock, you can use many tiny chips, too. Rip a strip to a 1/16th thickness and cut it to length to fit your groove, stacking as many of these as it takes to fill the slot.

Hope this helps.

PGJ