Quote:You definitely can't soak and bend 1/4" plywood- it's just too thick and the laminar construction
It is possible to bend (make sure it's exterior plywood) 1/4" plywood along its long grain. I've made several of our gladiator shields in this way.
I took some scrap plywood and other stuff, and built a wooden tank of sorts, larger than a scutum. A sheet of black construction plastic lain inside, filled with water in the sun makes for warm water.
Put the scutum blank(s) in the water, set some sticks of scrap wood between them, to make sure they get water everywhere, and weight them down with some bricks or something. After two or three days, you should be able to bend the plywood in your frame, press, barrel, or whatever your bending rig is. Don't forget to put some reinforcement strips in the water to soak while the blanks are drying.
The full strength wood glue will penetrate better in a wet wood surface, but be sure you use plenty of glue. Paint it on with a rag or old brush. When the glue begins to penetrate both surfaces, then put them in your bender, and put the pressure on. That way, there will be new glue
in both outer wood surfaces, as well as
between the woods. It will take a few days for the glue to dry in this wet environment (like pottery clay, when it no longer feels cooler than the outside air, it's dry...leave it one more day). When done, even one layer of 1/4" will hold its shape pretty well. Now it should be time to take the wood strips out of the water, and bend them in the same shape.
Put the wood strips (be careful they are not on the bender at an angle, or you'll regret that mistake!) straight across the bender barrel (or whatever). I hold them down with a scrap of plywood about 100mm wide, bends like paper...and squeeze it with cargo straps.
When they've dried, clamp and glue them to the blank and clamp in a curved surface, like your bending rig, until this
glue is dry. Your shield will hold its curve.
We use an oil drum, for the reason that we haven't built a proper scutum press yet. One advantage here, though, is that the wood strips can be bent around the same shape as the sheild, and the glued support strips can be held onto the same rig, so everything stays nice and similarly bent. In a press, the wood strips will be a different radius from the outer edge AND the inner edge of the scutum, so that might be an issue. Can't win an argument with plane geometry.
That barrel method would probably not work for a three layer, historically accurate, laminating method, though, as it would be pretty difficult to keep everything lined up correctly while the gushy glue spread over everything. At least that's the impression I get from looking at that process.
M. Demetrius Abicio
(David Wills)
Saepe veritas est dura.