Hi John,

I make my strongbacks from 2 spruce 2x4s glued & screwed together. Any beam made from a single piece of wood is more likely to warp that a laminated beam.

Watch the grain pattern and the natural curve of the wood. Try to have any warps arranged to cancel each other out. Do a trial fitting to find the best assembly. Apply the glue, clamp one end, check the seam is straight. Add more clamps and screws as required.

Two 2x4s makes a good sturdy beam. I have a 1 foot lap joint in the middle so I can take the beam appart for storage or extend it easily.

Because double 2x4s are a bit big at this point, the ends of the beam are a single 2x4 "spliced in" [tendon joint]and bolted in place . These end pieces can be changed/angled as required to suit different designs. I plan to leave the end forms and the last form or two of my Guillemot permanently attached the single 2x4 as an "assembly".

Hope this helps. Enjoy your building.

Hank