Laminations

[DC]

Is a laminated piece of wood stiffer than a solid piece of the same dimensions? I'm mostly thinking of recurves(the bent part) but any input is welcome. I'm wondering if I can get away with thinner sections if I kerf my recurves.

[Aaron H]

It is essentially Perry reflex, so I would be inclined to say yes, it is stronger.   I'm sure the science team will be along to chime in though.

[Pat B]

Two laminations glued together are stronger than a solid piece of wood of the same thickness. The glue joint makes the 2 lams stronger than the sum of the two by themselves.

[DC]

Cool, that helps

[jaxenro]

So are three stronger than two?

[PEARL DRUMS]

Yes. That's why laminated beams are used in construction rather than one-piece large milled beams. Its also why plywood has 4-8 layers glued together.

[willie]

The glue joint makes the 2 lams stronger than the sum of the two by themselves.

PatB- what kind of glue do you see the extra strength with?

Jax- I see where you are going with that slippery slope Q.

PD-not quite. most manufactured wood products are designed with multiple pieces to utilize smaller pieces for economy and to create configurations not available in nature.

[PEARL DRUMS]

Have a read:

"Although the term engineered lumber is used to describe a variety of materials, most are defined as structural components that have been fabricated. Engineered wood is manufactured by bonding together wood strands, veneers, lumber or other forms of wood fiber to produce a larger and integral composite unit that is stronger and stiffer than the sum of its parts."

[PEARL DRUMS]

And just a bit more info:

"Glulam beams and wood I-joists can carry greater loads over longer spans than is possible with solid sawn wood of the same size," 

[willie]

PD-
can't argue with a unidentified source. what are you quoting? if I chip up an aspen tree to manufacture a sheet of OSB, the sum of it's parts might be....a pile of chips? 

"Glulam beams and wood I-joists can carry greater loads over longer spans than is possible with solid sawn wood of the same size,"

I do not think that "is possible" is meant as an absolute strength wise in the case of glulams.  "is economically possible" would be true.

There is a reduction of dead load when using sheet product for webs in I-joists, but that advantage s not really what the OP is asking about.

[PEARL DRUMS]

Answer his question if the rest of us are wrong.

[Badger]

  I know that laminated bow will usually have less thickness than a self bow by close to 1/8" on the average.

[PEARL DRUMS]

And I would say on average they hold their glued in shape better as well.

[Pat B]

Willie, I don't think the glue itself matters(within reason). It is the joining of the 2 lams that makes it stronger.

[jaxenro]

I was reading an old book the other day (Pope's or Ford's I think but it might have been someone else) and they were talking about making a bow from hickory where you cut the back off, swapped it end for end, and glued it back on. This was supposed to be stronger and less likely to break than a self bow using the exact same piece of hickory just uncut. I'm not sure if it was the glue or the fact that the grain was swapped so that (in theory) the different variations in the grain would cover one another that made it stronger?