Steam bending bamboo recurve?

[nabiul]

If anyone is still following, I'm going to try and save this malnourished bow.

A picture of the patient before the operation.


A little bit of the fade milled off to make a flat surface and the first incision. Diluted TB3 definitely does not soak through wrappings into the wood below.



Even more revelations about TB3, areas not exposed to air do not harden. The uneven joint at the end grain between the limbs was of a gel like consistency making a rubbery hinge at this point. Now I understand why Dave Mead is confident in using hot glue to assemble his bows, the gelled TB3 felt  just like hot glue.



And the first limb is off with most of the bamboo intact. My fears were unfounded, the poorly clamped TB3 joint was more than strong enough and stronger than either the bamboo or maple. More to follow in the future.

[DC]

What's your plan? I'm still watching

[Pat B]

Wrap the whole riser/handle area. Put glue down first for a little ways, wrap, glue another section, wrap and so on and finally add glue over the wrap, maybe watered down first then full strength. Trying to feather out your fades would help with the transition.

[bassman]

Either use hot glue with a full wrap on the limbs to riser or epoxy.If you use hot glue you can correct your mistakes. You can heat it back up ,and the limbs will pull off the riser.If you use epoxy you have to get the line up  right the first time. Mead sales quite a few of his bows, so he knows Hot glue, and wrapping work best, and is the cheapest way to go. TB3 is good stuff ,but not for this style of bow.

[nabiul]

The plan is to plane the limbs flat again, heat treat them and then glue them to some 1/4" thick oak slats. The oak would be worked to fade with the bamboo near the recurve and then assemble the whole thing again with the handle, maybe with a slightly more reflex this time. The question is whether to only heat the belly with a heat gun or do the whole limb evenly in the oven, and what would it do to the glued on tip overlays?

@Pat B, never thought about doing it gradually; initially I was just going to smear the whole area in glue and then wrap, but then I thought I would do a dry run first to see how it goes...and then I learned that I have two left hands and gave up the idea of wrapping on wet glue. Thanks, next time I will try it your way.

@bassman would you still say the same thing for gluing on oak overlays for 2/3rds of the limb length?

[bassman]

Nabiul, here is a 53 inch knock to knock bow with tip over lays, FF string, and Oak riser.The limbs are made with  Bamboo slats for the back, and heat treated Bamboo floor boards for  belly that taper from end to end when tillered. The riser  is hot glued ,and wrapped. The limbs are glued with Smooth On AD 40.Many guys on here use TB3 for limb glue ups with good success. I use Epoxy, because it is works best for me. This shows a different option. Maybe it will help. The working limbs are 20 inches long, and one and an eighth wide at the fades and taper to three eighth,s at tips. Over all length of the riser is 13 and three quarters of an inch. Braced at 4 inches it is 46 lbs. at 25 inches of draw.
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[bassman]

more pics

[nabiul]

Impressive, what do you think the max draw length is on that bow and have you ever chrony'd it?

[bassman]

26 inches. Never chronied, but it is a snappy bow. Not trying to steal your thread Just thought I might be able to help you with some ideas.LOL.

[nabiul]

Is that artificial sinew wrapping at the tips? I wanted to use the stuff, but it's waxed and I thought it wouldn't adhere to glue. My preferred draw is also around 31" which I think makes bamboo only limbs impractical for me.

Update: I cleaned up and heat treated the limbs which went pretty terribly; all of the recurve straightened out once heated and the treatment is uneven. some lengthwise cracks also opened up which I filled with CA. I originally cut the limbs from two different slats of bamboo and didn't check the density, one of them is significantly more dense than the other. The less dense limb is now glued and clamped to the denser of the two oak slats I bought.

I think I'm going to do a oven heat treat for my next bow and do a dave mead style construction, any tips for temperature and length of time for a good heat treat?

[nabiul]

The first limb is dry and ready for cutting, second limb is glued up and under clamps.



The limb roughed out, you can see from the glue line that I didn't completely flatten the belly side before glue up because I was afraid of making it too thin. Again my fears were unfounded. It's stiff...really stiff.. like 100lbs to make it bend and it will explode in the process stiff. Next I'm going to try to thin and fade out the oak while judging how much meat to leave for my desired poundage.

[nabiul]

Back to tillering again, with more meat this time. right now it's sitting at about 40# near a short brace height. Not sure how I want this to bend now, the recurves are gone and it feels like the tips should be doing alot more of the bending this time. How should I do the belly; flat, trapped, curved?

[DC]

 Flat is good. If anything maybe trap the back. Depending on the kind of Oak the bamboo might overpower it.

[nabiul]

Progress update.

I lost a lot of weight chasing out a hinge that formed in one of the limbs where the oak slat ended and transitioned to bamboo only. Now I'm scraping the other limb which is stiffer. Currently sitting at 35# at around 29" which is 2" shy of under my chin but it stacks rapidly if I try and draw it more. I'm afraid of going further and ending up with an underweight bow while trying to even tiller which may not even fit my shooting style which I don't even have yet.



The tiller is obviously out by quite a bit but I thought I'd check exactly how much in photoshop by flipping and overlaying the image onto itself.





The awful string follow as was expected with bamboo after reading Tim Baker's article on bow woods.



Now the million dollar question is should I take it to the field and shoot it or keep scraping the stiffer limb?

[simk]

this doesn't look too bad - just pretend the uneven limbs were done intentionally to get a positive tiller. i'd take it out and shoot it if it's shooting good start a new bow. If it's not, start a new bow  cheers