Ipe core on trilams?

[kevinsmith5]

I knkw this isnt too primitive a question, but this is the only place I know to ask. I've recently seen several longbows with bamboo or hickory backing, a hickory belly, and an Ipe core. I was always of the olio on that the core needed to be a light but crush resistant wood that was really just there to thicken the stave. Ipe seems to me to be just the opposite if what you want in the middle and more what you want in the belly. i thought cores should be a layer of flattend bamboo or hard maple. Am I wrong?

[Pat B]

I guess ipe would make a good center lam but with its compression strength it would make a better belly lam with maple or boo for the center lam and boo or hickory for backing.

[Cameroo]

I think ipe makes a good center lam. Although I've only tried that with one bow so far, the bow seems to perform very well with excellent cast for its physical weight of 687 grams. (http://www.primitivearcher.com/smf/index.php/topic,39349.0.html)

I'm not sure why you would want to use a tension strong wood like hickory on the belly though... 

[DarkSoul]

A core is not " just there to thicken the stave". Although it is true that the belly and back are working harder, the core does have some true function. A core of balsa wood will not perform good (okay, exaggeration, but you get the point). The mass principle clearly explains that the mass is the factor that ultimately matters, not the mass distribution. Ipé is a really stiff wood, per mass unit. So an ipé core will mean a stiffer core than a core made of laminated bamboo or maple. It is the stiffness that makes ipé a good core. Granted, many woods will make a good core. The belly and backing are more important to choose wisely, but also the core has a function. A core of steel will be too heavy for the stiffness it delivers. Western red cedar will be too soft and lacks shear strength, while the stiffness per mass is excellent. Maple is fairly stiff and easy to work and glue.

[Thesquirrelslinger]

Palm? its pretty stiff and strong.

[toomanyknots]

I have recently been wetting my beak with bows like these lately, so I have acquired some thoughts on the subject.  I am not in love with super dense tropical woods as cores as much as the rest of the world I guess. I like the looks of em fine though. Like, bloodwood for example makes a beautiful core, especially in a hickory (or bamboo), bloodwood, ipe trilam. But all those woods in the end result in a heavy bow most of the time. I would like to try padauk as a core as it is a nice orange color and seems a lot less denser than bloodwood. Bloodwood seems incredibly resiny too. The piece I got I thought my bandsaw was on fire because of all the smoke coming off the blade from the resin in the wood. I think yellowheart wood be nice as a core, it is lighter and I hear it is a good bow wood in general, or at least in compression. I have one glued up right now. Although for the most part hickory hasn't disappointed me one bit as a belly wood. With elbs anyway. I reflex my glue ups and end up most of the time with a tiny bit of reflex at rest, or straight, with bows around 60#. Warbows take a bit of set, so far, but only 1 - 1 1/4" I think so far. Like any other decent wood, I don't heat treat keep in mind. Which is more than fine by me. I think one thing people don't think about to reduce set in a bow is a quality backing. For example, when gluing a reflexed bow into 3" reflex or so with a good quality hickory backing, the hickory will help hold the bow into reflex just as much as the belly will. I have experienced this even with softer maple bellys, that would usually take set. Also when I have had bows delam, (or rather forced them to myself), before delaming the bow would have about 1 1/2" reflex at rest. After delaming, the belly actually took set/string follow, so it was clear that the backing was the only thing holding the bow into reflex, like sinew will. This bow was initially glued into about 3" reflex. Some people say the more laminates the more stiffness. Some people say that isn't true. I don't really know. I have been told that ipe's stiffness is what makes it a great wood, and that even though it is denser, that pound for pound a well made ipe bow will be lighter actually than a bow made of a lighter but less stiff wood, but I sure haven't been able to do this myself in practice?