Proper bow design effieciency, performance, and reliability. Where can it meet?

[Chris grimbowyer]

Hello gentlemen, I have recently been brainstorming on what I want to do with some truly blessed osage staves I have cut the past year. I cut a tree that was 15" in diameter before split. The tree was growing on a fence line, leaning inward. From all the staves it yielded the one on the inside curve of the tree was beautiful. It has some serious reflex, the fattest rings of the whole tree, and it was the darkest amber when fresh cut in color, compared to all the other staves from the log. This stave was wide enough to get two out of it. Now I am planning on chasing the highest performance self bows I can with these staves. I would like to do a custom Holmegaard (reflex/deflex) straight stave vs a recurve and see which I like more. For the holmegaad I wanted it to be 68" long. Pulling around 50-60# @28". I am planning on making it 1" (parallel width) in the bending section 2/3rds of the limb, then have the thin reflexed tips. What do you think about this design? My other question is, I don't know much about what makes a recurve a fast shooter. So should I go static/ or working, and at what length down the limb should I induce the recurve?   Thank you all for your time.

[Jim Davis]

First, the inward curving side of a leaning tree is known as compression wood. It typically has wider growth rings, as your sample does. It is weaker in tension than the other side of the tree and is commonly considered  the inferior side from which to make a bow.

However, most wood, including Osage, is stronger in tension than compression so most compression side Osage staves make good bows despite the above considerations.

Second, recurved limbs are of more help in making  a smooth draw and reducing string angle than about improving speed. That is more dependent on such things as outer limb mass, having good force/draw numbers and a long power stroke.

Jim Davis

[Joec123able]

If youre Going to make a self bow that's recurved you cannot make working recurves because they will straighten right back out eventually so go with static

[Chris grimbowyer]

Those are both helpful comments, thank you. I could consider a light backing like flax? It's not that I am only about speed bows. I simply like to learn as much as I can about bow efficiency through personal experience while I have the oppurtunity, that is with selfbows. I'd love to make a laminated BBO but I'm more of a selfbow enthusiast. I am trying to push the selfbow limits with atleast one of these staves to see what I get.

[ssgtchad]

I think i'd go a little wider, 1.5 to 1.75 " it will help prevent set IMHO. But I still a lot to learn. Cant wait to see what you come up with!

[Joec123able]

The best way to get as much speed as you can is to get your tips as narrow as you possibly can. When I make bows I don't worry much about speed. But the lighter weight your tips are the more speed you will get that's one tip on speed

[Badger]

  Check out some of the bows being made over at Twin Oaks. This is a group of guys consistently putting out top notch bows in all aspects including performance. 1' wide limb will likely breakdown and cost you some performance, you don't see too many holmgardes with and r/d profile for a good reason, they are hard to keep stable. Just keep the outer limbs narrow and you should be fine.

[blackhawk]

Hey Steve...good to see ya around

Use Steve Gardner's mass principle and make narrow outer limbs for the last several inches

I'd go at least an 1 1/4" wide for your holmgaard if your still planning on going parallel for 2/3 of the limbs...and make an Eiffel tower taper to .250"-.300" at the string grooves and use tip overlays...they are a must to achieve that narrow....id maybe change up your front profile to starting at  1 3/4 wide at fade and semi pyramid taper to 1 1/8" two thirds down then Eiffel tower taper to the same dimension tips I suggested....if done right and used with the mass principle you can acheive fast speeds in a stable durable good shooting bow.

[JackCrafty]

Yep, 1" wide limbs on a Holmegaard is a bit too narrow.  I just finished a Mollegabet style (similar to Holmegaard) and the limbs were 1-7/8" wide.

Check out this thread:

http://www.primitivearcher.com/smf/index.php?topic=24295.0

[Chris grimbowyer]

The outer limbs being thin is certainly the most crucial attribute of the speed. I have read the TBB IV chapter on the mass principle. Thank you for your input on that anyways. I can see that 1" could be too narrow. I was considering it simply because of the long length, but then again all the bend being in the mid limb, I can see that it would take less set with extra width. Now I am wondering if I should leave the bending section a parallel width of 1 1/4, or 1 1/2. Or I could have it slightly taper (By no means steep) maybe 1 1/2 to 1" before the actually eiffel tower taper to the tips. The stave is naturally reflexed more so on one end than the other. So this is mainly going to be toawrd one end of a limb. I would heat bend the other to match its reflex. I am probably going to come out with a somewhat reflex deflex looking holmegaard. I will be sure to take my time and be very careful so it doesn't end up strung backwards. When I get the staves down to a growth ring here soon I will post some picture, and keep you guys up to date.    I hear Native Americans valued trees for bows which were struck by lightening because they have "Power in them". Anyone have anything to say about this? I found it quite interesting.

[blackhawk]

I've made oodles n oodles of holmgaards n mollegabets n lever style bows from 50" bendys to 76" long stiff handled bows with almost every kind of side and front profile you can imagine......and this bow here is really close to what your wanting to do and  is still one of my fastest bows of these types... accurate shooter to boot...I'd highly recommend following this example somewhat

http://www.primitivearcher.com/smf/index.php/topic,28407.0.html

[Badger]

Blackhawk, I thought about your bows when I was posting. I figured you would be along shortly.

[Pat B]

Hey Steve. Been missing you.    Will you be coming east this spring?

[Badger]

  Pat if I can find a partner to split expenses I think I will, negotiating with someone as we speak.

[mikekeswick]

Follow the dimensions Blackhawk gave you. He knows what he is talking about