Author Topic: juniper bow design.  (Read 9006 times)

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Offline Turtle dragon

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juniper bow design.
« on: March 13, 2014, 01:44:21 am »
I've recently come across a beautiful juniper log around sixfoot long and 3-4 inches thick. I know most designs for juniper are similar to English style long bows, which I have some experience making. I'd like to try a flat bow design, similar to that of
Osage bow. would there be any problem with that design? or should I stick with the trusty long bow?



Offline Wiley

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Re: juniper bow design.
« Reply #1 on: March 13, 2014, 01:54:48 am »
Do you know the species of juniper?

The only ones I have really looked into was eastern red cedar (its a juniper). If it has similar mechanical properties to that and I wanted a flat bow I would want to back it with something. Tends to be much better in compression than in tension, which if I understand it right is why the ELB is an effective design for it with the back being larger than the belly those forces are brought closer to being equal. With a flatbow you will probably need something able to take the tension.

Feel free to correct me if i'm wrong but this seems to make sense in my head.
« Last Edit: March 13, 2014, 02:06:52 am by Wiley »

Offline Turtle dragon

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Re: juniper bow design.
« Reply #2 on: March 13, 2014, 02:11:44 am »
Common juniper from the sierras above 8000 feet. What if I was able to Include sapwood in the backing? most juniper long bows have a sapwood backing, although I understand it's not entirely necessary with a self-long bow

Offline Bryce

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Re: juniper bow design.
« Reply #3 on: March 13, 2014, 02:20:46 am »
Juniper makes a great short bow! Best when the heartwood is backed with sinew.
If you want a selfbow make it as short as possible while still keeping it in a safe margin of reason ability.
 
From talking with Keenan and other juniper addicts it makes a sluggish longbow (as far as common juniper concerned)  :(

Have fun! Juniper is some fun wood to work :D
Clatskanie, Oregon

Offline Peacebow_Coos

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Re: juniper bow design.
« Reply #4 on: March 13, 2014, 02:24:14 am »
I made a sinew backed juniper paddle bow that really was a sweet bow, I like the combo as did Ishi.  Rawhide would probably work, the stuff that I had was from Oregon so it might be different but it was real hard to break test pieces definitely great compression properties.  I would keep a ring and go for it or sinew it.  What length are you thinking?

Offline Wiley

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Re: juniper bow design.
« Reply #5 on: March 13, 2014, 02:24:33 am »
Someone with experience working with juniper and it's mechanical properties would be better qualified to answer that.

Your humidity probably isn't as high as it is here in Georgia. If I lived in an area with a low humidity, a sinew backed juniper flatbow would be the design I would like to make. A search turns up a good number of other successful designs using this combo.

mikekeswick

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Re: juniper bow design.
« Reply #6 on: March 13, 2014, 02:27:13 am »
Sinew back it.
It's heartwood is better in compression than thesapwood is. If I hada choice I would use sinew backed heartwood.

Offline Turtle dragon

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Re: juniper bow design.
« Reply #7 on: March 13, 2014, 03:07:52 am »
what if I tried to use another wood like hickory? I've never tried to do a wood backing but I'm willing to ruin a stave or two to learn the technique.

Offline wizardgoat

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Re: juniper bow design.
« Reply #8 on: March 13, 2014, 04:17:04 am »
I'm currently working on a Rocky Mountain juniper bow, from a 4" diam branch. It will mostly be sapwood, except for some heartwood at the handle and fading out. I'm playing it safe at 55", slightly bendy handle, 2" at the fades. I flipped the tips 2", and will brace is backwards and lay down 1 nice layer of sinew.
I'm following the advice of someone who has made many similar bows, but this is my first in this style. I'll let you know how it goes!

Offline Michael Scott

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Re: juniper bow design.
« Reply #9 on: March 16, 2014, 01:45:07 pm »
Good morning, guys.

This looks like a good spot to glean some information. Around this time last year, I split a juniper log in half that I brought from Montana to Texas when I moved in 2011. The tree grew nearly straight as an arrow, but when I split it, I found the 8' log to have almost a full 180* twist, end to end. I split one half down a bit, and roughed out a 60" tip to tip bow. I would have to measure widths, but it is around 1 1/4" at the handle, tapering to around 3/4" at the tips, I think. There is some (maybe 4-6") twist at each end of the limb tips, too. Not really knowing what I was doing, I started forming it into basically a flatbow, with a kinda trapezoidal cross section. Of course, this was before I was informed that juniper does well as a D bow. I think I can still form it into a shallow D, and I am considering trying to trim off as much twist as I can by shortening the limbs a bit.

I started asking questions about backing, and got three basic varying answers. Somebody told me to leave the cambium on and back over it with rawhide or sinew. Others told me to strip the cambium off completely and back it that way. Then, recently, I was told by another guy that he had seen juniper bows that were stripped clean and left unbacked. I saw acker's juniper bow, and it looks great unbacked.

Anyway, any information or advice you guys can share would be most appreciated. I would like to try and finish this bow and see how it works out.

Thanks!

Michael
Michael Scott

After 10+ years shooting traditional archery, I am now interested in progressing farther back in time to primitive archery.

Offline Bryce

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Re: juniper bow design.
« Reply #10 on: March 16, 2014, 02:16:24 pm »
Cambium need to come off. There is no other way. The backing need to be glued securely to the wood.
Clatskanie, Oregon

Offline Peacebow_Coos

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Re: juniper bow design.
« Reply #11 on: March 16, 2014, 05:05:40 pm »
I'm sure you could leave a 60 inched unbacked if the design were right all I know is the two I've made (one still drying almost been a year)  I rasped the back to the shape I wanted pretty much regardless of knots or violations then sinew backed.  Seems to work well as long as knots are filled and you get your sinew on right

Offline Ross.m.

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Re: juniper bow design.
« Reply #12 on: March 16, 2014, 05:10:38 pm »
You could try making the same sort of bow that Ishi made. He made great bows out of juniper, he also backed them with sinew as stated above. He also made them very small, in the 40 inch range