Seems like every bowyer offers some type of bamboo am as an option. I have always heard that bamboo, having such low mass and high strength, was a smooth, fast backing material, BUT it seems I read in some older source (can't remember which) that Bamboo fails faster (shorter lifespan) in tension or compression than, say, a maple lam. Implying, therefore, that Bamboo doesn't last as long (catastrophic failures and delams), or that the performance fades over several thousand shots.
Is this true? I can't believe that all these well-regarded bowyers would use a material with a shorter working lifespan unless it came with dramatic performance results. Even then, I'd rather pass my bows on than gain a few FPS.
Maybe I missed some new Bamboo development over the last several years. Maybe it has something to do with the meaning of "vertically stacked", which I am also unclear on.
Thanks!
-Charlie
Actionboo (vertically stacked bamboo) is laminated bamboo flooring cut into limb laminations. In building construction The use of laminated woods such as plywood and LVL beams most made of fir creates an incredible amount of strength out of less cubic dimensions than stardard lumber. Although laminated contruction material is stacked with the grain going in opposite directions which creates most of it's strength. Actionboo still I beleive would be less likely to loose it's structual integrity through the whole limb like a natural wood limb core. Natural wood can be funny a certain coarse of grain check or a knot can cause stuctual failure in a piece over time. I think this is why this is why a lot of bowyers offer actionboo or actionwood laminations for warranty reasons.
You're right in that boo isn't very strong in compression (weaker than red oak actually), that's why on the boo backed boo bows (either vertically stacked or raw) you'll see them start out with more reflex to end up with the same final profile as osage or similar wood.
However, lams in between glass behave much differently than a belly lam on a boo backed bow. In this case it's the glass (or carbon) that's taking most of the tension and compression forces, with the wood lams being there to separate the two (build strength) without adding too much weight. Here's where natural bamboo shines IMO (as well as yew and walnut). The actionboo is just as dense as most of the common lams (maple, elm) but b/c of it's construction you don't have to worry about any faults (grain checks etc) that you do with natural wood.
That's my take on it from tinkering anyway ;)
Howard Hill started making bamboo/glass laminated bows in the 30s. It's durability has been proven long ago. A big reason for subsequent manufacturers/builders not using it is because good bamboo was and is hard to get. For my money, bamboo is the best lamination core material available.
Millions for fly rods were built with bamboo for the action it has. It is a very tough naturally renewable product for bows, that just happens to work great. As the core lamination of a bow there isn't anything finer in my book.