Joining Plywood

[Frosteez]

I am deciding the best way to join plywood. We need 4x9 3/4" Oak for the sides of a 5x9 Benroy> Can I biscuit join it? It will be single wall w/no insulation. Or is there a better way? All I can find from our supplier is 4x8 sheets. Thanks

[Sparksalot]

Have you tried wood working specialty stores as a source? I was able to get
4x10 red oak that way. They needed 2 days notice, but got it no problem.

[Steve_Cox]

When joining plywood there is the best way, then there are the easier ways, one of the easy ways is good enough for a teardrop. If you were building a boat the best way is an 8 to 1 scarf joint. Teardrops can use splines, biscuits, or a butt splice with a backing board just to name 3. Unless you are one of the router gurus here, one of those three would probably suffice.

[len19070]

I like splining plywood to join it.



I've made some pretty big sheets of plywood.



Happy Trails

Len

[Joanne]

I did a three inch lap joint using a router. A lot easier than a scarf, but still probably an overkill for a tear.

Joanne

[cracker39]

This is a topic that I just became interested in, as I got the bug to build a kayak and am going to use 4x8 1/4" plywood and the yak is 11 feee long...that means joining plywood.

I considered just but joining with a backing piece, or butt join at a frame where I can just screw down the ends together on the frame. The latter might result in a not perfect curve where they join.

As 1/4" ply is a little thin for splinig or biscuits, the better method is a scarf joint. I just tried making the angled ends by stacking some sample pieces at 3" intervals and using first my 3 1/2" power hand planer, then belt sander to get the angles to join. The drawing below is how the technique works if you haven't seen it done. The angled ends are supposed to be feathered down to a perfect edge, but mine were not so perfect, still with some tiny width to the edge. I drew how it is supposed to look and how mine looks. I'd have to do some filling with bondo after the piece is on the boat and curved to fit the frame. It will have fiber glass mat and resin over it anyway.

I glued two pieces together and tomorrow, I'll see how strong they are. It it looks OK, I'll try it with the plywood sides. I think I'll just butt join the bottom as there isn't as much curve to it and making the angled cuts are tedious.

[cracker39]

Today, after more than 12 hours drying, I tested the joint and it seems very strong. I guess I'll use this scarf joint on my 'yak sides and butt join the bottom at a frame.

[Juneaudave]

Here is a pretty good method...I personally use a scarfing jig...

Oneoceankayaks