Pergola Arch.jpg
We made a 36' long laminated box bean, non- structural for a poolside project. 12" wide Cedar, 1/4" thick, joined with scarf joints for length, bent on a form of sorts, and then placed into the upper and lower 'faces' of the beam. Epoxy, Western Red Cedar, KD, and scuffed faces on the laminations.
I have recently learned that about 20% of W R Cedar has so much oil/resin that TB 1/2/3 and other water based glues are failing to set. The practice of wiping with acetone may help, but is hit or miss. How will you do that with mortise and tenon joints?
I also learned that a freshly cut surface glues better than one that is a day old. I'd scuff each ply just before gluing. Epoxy is a rare glue in that it is a true gap filling glue with strength even in the gaps, and it does not like/require lots of clamping pressure.
If I were where you are, I'd build the form for the one piece beam. Plan on 3/4" W Oak. Scarf them together, staggering the joints. Buy lots of epoxy.
I want to stay as close to the edge as I can without going over. Out on the edge you see all kinds of things you can't see from the center.
- Kurt Vonnegut