Author Topic: Sinew hickory horn bow  (Read 523 times)

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Offline dieselcheese

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Sinew hickory horn bow
« on: July 09, 2019, 05:56:44 pm »
I'll preface by saying that this bow doesn't really resemble a traditional horn bow so I decided not to put in the horn bow forum.  It's more of a tri-lam that happens to use sinew and horn.

50# draw at 28"  (give or take a pound or two depending on the mood of the bow)
58 inches NTN
11 gpp arrows chrono'd at average 161 fps

In my quest to find traditional bow materials that can handle my extreme dry weather I've decided maybe this combo will work.  I used a hickory stave as the core with steam bent reflexed tips.  Laminated the horn on using G Flex epoxy.  Has maple underlays on the tips, butted up to the horn.  Horn nocks as well.  Finished with a tung oil and Tru Oil combo.

I covered the sinew with silk from a Goodwill blouse.  We're so dry here that sinew and hide glue behave funny.  The glue becomes real brittle, and sinew fibers will often lift up just while sanding and strands will pop loose while exercising the limbs.  I probably need to squeeze out less glue from the sinew, but if I use too much glue I get perpendicular cracks that go pretty deep, to the point of creating a hinge.  The silk over-backing seems to be the ticket so far...fingers crossed.  Thought about doing like Ed Scott and using Titebond but will only go that route as a last resort.

To give an idea of my challenging weather, today the measured humidity at the lab sites was 9% with a high in the mid 80's.  And it rained two days ago!!!  The ground is still wet in the shaded areas. 

So far I've shot about 300 arrows.  This is only the second recurve I've gotten to the shooting stage and I was extremely surprised my tip alignment came out perfect, no tweaking required.

Sorry for the crummy cell phone pics and wasn't able to take a selfie (how I hate that word!) at full draw.  Upper limb looks way out of tiller in the fist pic but it's just the crummy phone camera and picture angle.







« Last Edit: July 09, 2019, 06:10:33 pm by dieselcheese »
Trying is the first step to failure
-Homer Simpson-

Offline Hawkdancer

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Re: Sinew hickory horn bow
« Reply #1 on: July 09, 2019, 07:16:45 pm »
Looks good to me!  But I'm new!  The hickory seems to hold up well to the high and dry, though
,Hawkdancer
Life is far too serious to be taken that way!
Jerry

Offline bownarra

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Re: Sinew hickory horn bow
« Reply #2 on: July 09, 2019, 08:58:26 pm »
Cool bow :) I think you are right about hornbows being the answer to your humidity issues. They can easily handle the extreme dry condtions you have BUT you must equilibrate all the materials to your conditions before using them.
To stop sinew strands etc lifting you need to alter not necessarily just the amount of glue but make sure you are using the correct thicknesses of glue. Firstly size very well with about 20 coats of no more than 5% glue. At least the sizing coats won't take long to dry where you are! Then use 25 - 30% glue for your first couse of sinew. 20% for the rest of the layers. DO NOT use any modern method to 'squeeze out' the 'excess'. Ok on a wooden bow but as the sinew isn't very strained but hornbows are a very different thing. The sinew layer must be sound and it won't be if you squeeze too much glue out.
The reason you haven't got better performance is that hornbows need a shorter working limb. You could achieve this with this design by reducing the thickness taper of your core before adding the required amount of sinew. Thus concentrating the bend closer to the handle giving a longer return path for the tips.
Anyway cool bow and good to see people thinking out of the box.

Offline dieselcheese

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Re: Sinew hickory horn bow
« Reply #3 on: July 10, 2019, 04:41:43 am »
Thanks for the info, Bownarra.  I've been kind of shooting from the hip on this.

So, using homemade hide glue, how does one know the percentages?  I'm guessing by drying out the glue and reconstituting by weight when it's time to use it?

Trying is the first step to failure
-Homer Simpson-

Offline bassman

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Re: Sinew hickory horn bow
« Reply #4 on: July 10, 2019, 05:19:28 am »
Good speed, nice paint,and good work. It looks good.

Offline StickMark

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Re: Sinew hickory horn bow
« Reply #5 on: July 10, 2019, 07:28:45 am »
Regarding the humidity swings, I know the struggle.  I am not a big fan of modern sealers, so I build the bows somewhat overbuilt (stronger), for still-appreciable-poundage when the rains come in.

That is a great looking bow. I too appreciated your sharing of ideas to deal with what I assume is the Southwest environment.

Offline dieselcheese

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Re: Sinew hickory horn bow
« Reply #6 on: July 10, 2019, 11:05:10 am »
I too appreciated your sharing of ideas to deal with what I assume is the Southwest environment.

Yes, sir...mountains in northern New Mexico.  Just wish we'd have gotten here sooner so I could've looked up Ed Scott.

Thanks for the complements,  guys.
Trying is the first step to failure
-Homer Simpson-

Offline StickMark

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Re: Sinew hickory horn bow
« Reply #7 on: July 11, 2019, 04:39:46 am »
In Tucson, AZ, area, the humidity had been in a range of 6% to 22%.  Is that similar to conditions up there? 

Offline dieselcheese

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Re: Sinew hickory horn bow
« Reply #8 on: July 11, 2019, 03:31:12 pm »
In Tucson, AZ, area, the humidity had been in a range of 6% to 22%.  Is that similar to conditions up there?

Very similar.  My home sits at 7500 feet and as I posted in another thread it lowers vapor pressure.
Trying is the first step to failure
-Homer Simpson-

Offline bjrogg

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Re: Sinew hickory horn bow
« Reply #9 on: July 11, 2019, 03:54:11 pm »
Nice bow dieselcheese.
Bjrogg
A hot cup of coffee and a beautiful sunrise

Offline Badger

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Re: Sinew hickory horn bow
« Reply #10 on: July 11, 2019, 05:12:58 pm »
 Nice bow and nothing wrong with the performance you are getting.

Offline silent sniper

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Re: Sinew hickory horn bow
« Reply #11 on: July 12, 2019, 09:28:07 am »
I'm glad to see you found a design that would work with your climate conditions. Nice job on a great looking bow!
-Taylor

Offline PatM

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Re: Sinew hickory horn bow
« Reply #12 on: July 12, 2019, 02:52:27 pm »
Nice work.

 It may be my imagination but it seems like Mike might have returned yet again. ;)