Let's talk core lam's

[twitchstick]

I bought some bamboo and some osage boards. I had not thought about doing Trilams at first but I have being seeing some post on doing them. I'm just looking for some opinions on core lams. How much do the benefit? pro's and con's, kinds of woods? Any thoughts or theory's you have would be appreciated

[takefive]

The two main reasons I use core lams is first, the osage boards I buy are 5/8" thick and when I rip them into two 1/4" thick lams, I need a core lam or a long power lam to add to the stack to give me the thickness I need at the handle and past the fades.  Second, it's easier to get the R/D shape with 3 lams instead of two.
I've used hard maple, walnut, cherry, and red elm for cores and haven't noticed any real difference performance wise between them. They're all in the same ballpark for SG and I would imagine that the tension and compression work is done by the back and belly lam anyway.

[mikkekeswick]

Yes it makes little to no difference.
Common sense would tell you that low s.g. cores would perform better but I haven't really seen the evidence with the chrono.

[monterey]

Can one go too low in SG with the core lam?

I would not use balsa, but as an example of extremes, would it hold a risk of failure?

Like Mike says, common sense says that a lighter core wood should perform better, but can it get too light (weak)?  I have this picture in my mind of a very light core crushed between the back and belly!

[takefive]

That's a good question, Monterey.  I have an Eastern Red Cedar board that I've thought of using as a core lam.  As light as it is, I've wondered if I'd have to go a bit thicker than I would with maple, etc.
This stuff is feather light, but pretty elastic and pretty good in compression.

[mikkekeswick]

All a core has to resist is shear. Not tension  or compression.
I've had core failures. African padauk being the last one. The grain wasn't the greatest and it was in an elb, hickory back, ipe belly. Started hearing the dreaded 'tick....tick' getting close to full draw...could not find a problem...it was the next day when I came back to it I noticed cracks running right through the core for almost the full length of the core.  
There are reasons why maple is a great core wood!