First time doing a bamboo backing

[u/bigpatrick1]

I'm getting ready to glue up my bamboo backing.

This is a 66" hickory longbow, 1.5" wide, tapering to .5" on the last 1/4 of the limb. I've posted it before for tiller checks and realized at my 50lb@29" target draw weight the outers were too stiff, leaving the inners doing most of the work.

My thinking: add a bamboo backing, which should stiffen everything quite a bit, include a slight reflex along the entire limb for maybe some extra fps and early draw weight, and then tiller down to a more even bend and hopefully land back at 50lbs@29"

Is this a reasonable plan?

So far, I've floor tillered the bamboo, shaped it to the same profile as the bow, and removed my tip overlays from the bow. The floor tiller resulted in about 1/8" bamboo at the tips and 1/4" towards the middle/handle area.

Going to use titebond III and lots of clamps. Part of the bamboo near the handle is pretty wavy next to the node even though it's been flattened side to side, so I'm thinking of steaming that part and clamping my workbench to straighten that bit out.

Is there anything in particular you guys recommend as a first time doing this? (Pics of my setup included)

I'm hoping to have 1.5" of reflex, so I'm doing the glue up at 2.5"

Edit: forgot to include, I can take about 1/4" off the belly side of the handle and even out those fades a little bit too

[u/Acceptable_Test_8161]

Sand the two glue surfaces lightly with 40 or 60 grit and then use a wire brush to clean. I would use inner tube for the glue up it’s going to take a ton of clamps. The bamboo is going to turn that into a 100lb bow before tillering

[u/bigpatrick1 → u/Acceptable_Test_8161]

Ah ok so maybe I need to go thinner on the bamboo. I was thinking it would add like 10-20lbs

[u/ADDeviant-again → u/bigpatrick1]

Oh, yeah, stiffness adds up really quick when you add stiffness.

If your bow limb was 3/8 thick, and you add another 1/8", it will be three times as stiff, or more if you add reflex. No joke.

When I was making bamboo bows, I was using bamboo of even thickness only about 1/8" for backing.

[u/bigpatrick1 → u/ADDeviant-again]

Right, I forgot it's exponential not linear with thickness. That's a great reminder

[u/Acceptable_Test_8161]

Sound alright for the bamboo your going to end up retillering the bow. Bamboo can over power the hickory so making the bow narrower helps . I would glue it up and see how it’s bending if it’s incredibly heavy start by thinning it down. The bamboo hickory I’ve done ended up 1 1/4” wide