Maximising draw length on a short bow.

[Julian]

I've been trying to cajole a good bow out of some old, dry Osage, but due to its short length and my inexperience I've had several failures. Is it possible to achieve a 27" draw with a 50" bow? How should I try to get the most out of the few workable staves I've got left?

On another note, the sapwood on this osage seems to have weathered to a dark brown colour, and it's quite crunchy/brittle (I dunno how to describe.) Should I remove this and chase a ring, or leave it and back the bow, or something else entirely? I'd love to hear your thoughts. I'm going to post my current WIP for tiller help next time I get out in the shed.

[Pat B]

I think you'd be hard pressed to get 27" from a 50" bow unless you added sinew. The sapwood should be removed. I've made osage bows with sapwood left on but I was sure the wood was handed properly off the stump and during the drying/seasoning period.

[huisme]

http://www.primitivearcher.com/smf/index.php/topic,49241.msg672094.html#msg672094

46"ntn, pulled to 25" fine and chrisaled at 26". I'm sure smoother/more thorough heat treating would have helped, but I'm still shooting this thing.

Flip the tips and make every inch of wood pull its weight.

[bushboy]

Osage molly,53"ntn drawn to. About 30",so I think it's doable.

[huisme]

Does that molle have a bendy handle? I'm already sure molles can be drawn especially far by virtue of the levers minimizing string angle but my most extreme pull with them was a 7" stiff handle for 55" of working wood and levers, pulled to 29" with an extra inch for security. I've been a little shy about their already limited working wood but it seems I could get away with more.

[mikekeswick]

A low string angle will increase strain not lower it as the benefits of a lower angle effectively bend a stiffer working limb due to better leverage.
Personally i'd sinew back it, bend in short sharp recurves, make the handle bend a little and tiller slowly!
You can of course splice in some tips. I have done this on a couple of 'too short' staves. If you look where branches come off trunks you can easily find 'grown in' recurves and as these haven't had to be weakened with steam you can make them super narrow. It's also easy to tweak them shapewise (steam) without worrying about breakage.

[huisme]

I think a lot of the drawx2 rule-o-thumb is more related to string angle than wood capabilities. Locust's tendency to fret hasn't stopped me from overdrawing as much as string angles causing excessive stack and even failed to hold the string securely if I don't flip the tips or use levers long before the wood fails.

Locust's tested modulus of rupture is higher than osage's projected numbers, meaning it would be less likely to fail in tension and not need sinew as quickly as osage, but of course those numbers must be false

[bow101]

Osage molly,53"ntn drawn to. About 30",so I think it's doable.

Thats fantastic for a shorty, my hats off to you.   

[Julian]

Thanks for all the great advice guys. I'm not quite confident enough for a molle yet but I'm going to go for a bendy handle pyramid design and see how it goes. I've started removing sapwood. Hopefully I can get this to a nice 40# but 30# would do just fine.

@bushboy & Huisme those are some lovely bows I'll try to follow your example.

Here's my last effort, which turned out pretty crap so I've got some mistakes I'll be more careful to not make.
http://imgur.com/a/jNXqC#0

@pat & mike I don't have sinew but I have some flax stricks in the post. would that do the trick?

[huisme]

That bottom limb is pretty close; make your next bow match that, bend the handle a hair, you're on your way!

[mikekeswick]

No flax will increase strain due to it being so resistant to stretch.
Sinew has very low resistance to stretching.
Huisme - I think you missed my point a bit. A lower string angle effectively increases the leverage you are putting on the limb. Eg. you can lift a heavier weight with a longer lever. Lower string angle is the same as having a longer lever. Another way to think about it is lower string angle is a good thing because it stores more energy (all other things being equal).
I understand what you are saying about the x2 draw thing but that is simply linked also to archer comfort not just what the wood can take. The op has only so much length to play with and therfore a finite amount of wood to store energy. So lowering string angle will increase strain on the working limb.