: ???? I've built 2 Pygmy's and really found their approach simple and strong.
: Why would you fabricate splines that would be visible through the
: fiberglass? Or am I not getting the picture?

Hi Jim

The spline joint goes inside the plywood on both edges and is totally hidden. I seriously doubt it will help the joint in any way as the plywood, whether 3 or 4 mm, will be really thin after cutting out the kerf for the biscuit or spline. I think this would possibly weaken the outer sides of the joint and mot give much more strength than a regular butt joint. This joint is good for adding extra glueing surface when putting thicker ( 1/2 - 3/4" ) materials together in an end-grain situation. In the case where you are covering the materials with glass and epoxy on both sides, the actual glue bond falls a ways short of the strength gained by the glass sandwich. It's been proven over and over that the simple butt joint and/or the scarf joints are plenty strong for this purpose. In my opinion, this joint is way more work than the amount of useful strength difference it will add to the joint.

The spline joint is very useful in cases where you are joining sides of a cabinet or corners where only the glue joint is holding two pieces together, then they affectively tripple the glue area and increase the strength of the joint measureably by adding some side grain to the joint. It's a good joint and certainly won't take away from the strength of the panels, but takes some extra set up time, extra tools and, in my opinion, doesn't add measurably to the joint in the glass sandwich layup. Course, that's just my thoughts on this and no proof to back it up. ???? Take it with a granule of Sea-Salt!

Rehd