Author Topic: reflex/static re-curve sinew/oak/fiberglass combo!  (Read 4642 times)

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Offline tkdHayk

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reflex/static re-curve sinew/oak/fiberglass combo!
« on: January 07, 2017, 02:16:31 pm »
Unstrung: http://imgur.com/csOL7aw

Strung: http://imgur.com/jVpaNFp

4-5 layers of sinew, red oak board core. Bows is 2 inches at the widest point and tapers to the narrowness of my finger. Bow is in progress. All I have to do is add a belly. I was  planning on using horn but couldn't find any so I decided to try fiberglass for the first time. Not sure how well this will work out as it is a curious combination. I'm mostly concerned that the bow will be too light even after the fiberglass belly is glued up. I have pre-tillered the bow before adding fiberglass since I don't want to have to remove lots of material once it is glued up.

I want the the recurves to have extra support as well, so Ill have to heat treat the fiberglass into a new shape, then glue it on. Is this possible/safe? i was planning on using a heat gun  and bending it by hand. can fiberglass be molded with heat?

Is fiberglass supposed to be stiffer than wood for its weight? the black fiberglass lamination I got from an archery supply store doesnt seem stiff at all. how much weight do you think it would add to my bow? its 0.04' thick. Thickness with fiberglass held up to the bow: http://imgur.com/rF4VObJ

P.S. is there an easier way to post photos on here other than linking to a 3rd party image hosting site like imgur?




Offline penderbender

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #1 on: January 07, 2017, 02:49:49 pm »
This is a primitive forum. You'll have better luck asking that question on a different site. Why not just a wood belly? Cheers- Brendan

Offline 1442

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #2 on: January 07, 2017, 02:59:13 pm »
Beautifull bow so  far.
I don't think the FG is gonna do anything mechanicaly or astheticaly for it.

Offline loon

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #3 on: January 07, 2017, 03:10:25 pm »
I guess fg would be too stiff. what about "toxhorn"?...

Offline bubby

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #4 on: January 07, 2017, 03:16:54 pm »
Sorry no f- word allowed
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline osage outlaw

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #5 on: January 07, 2017, 03:20:32 pm »
Move it to the campfire page.  No glass fibers on the bow page. 
I started out with nothin' and I still got most of it left

Offline willie

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #6 on: January 07, 2017, 03:34:26 pm »
Quote
Is fiberglass supposed to be stiffer than wood for its weight? the black fiberglass lamination I got from an archery supply store doesnt seem stiff at all.


Yes, stiffer than everything else on our bow. Stiffness meaning a higher tensile and compressive strength. In a .04 thickness it seems floppy, but if it was half the thickness of the limb, you would see the "stiffness". I will bet that your choice of materials will also show you what sinew can do, as the belly might "overpower" the back, or at least make the sinew elongate and work more than it usually would, on wood/sinew bow without the f.ff..ff.... (I cant say it here, without ruffling feathers)

BTW, challenging design, and nice job so far.

Offline tkdHayk

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #7 on: January 07, 2017, 03:37:39 pm »
This is a primitive forum. You'll have better luck asking that question on a different site. Why not just a wood belly? Cheers- Brendan

I know, I wanted horn because it is stiffer against compression than wood and I could push the bow further than with wood only (longer draw length, more stored energy). because the bow is reflexed, I wasn't sure if wood would hold up at my desired 30 inch draw length. what wood would you recommend? bamboo?

Offline tkdHayk

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #8 on: January 07, 2017, 03:42:25 pm »
I guess fg would be too stiff. what about "toxhorn"?...

Why would it be "too stiff"? I have 5 payers of sinew so I don't see the back failing. Is fiberglass supposed to be stiffer than wood?

Offline tkdHayk

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #9 on: January 07, 2017, 03:51:16 pm »
Quote
Is fiberglass supposed to be stiffer than wood for its weight? the black fiberglass lamination I got from an archery supply store doesnt seem stiff at all.


Yes, stiffer than everything else on our bow. Stiffness meaning a higher tensile and compressive strength. In a .04 thickness it seems floppy, but if it was half the thickness of the limb, you would see the "stiffness". I will bet that your choice of materials will also show you what sinew can do, as the belly might "overpower" the back, or at least make the sinew elongate and work more than it usually would, on wood/sinew bow without the f.ff..ff.... (I cant say it here, without ruffling feathers)

BTW, challenging design, and nice job so far.

Thank you. I think I may have to add more than one layer of fiberglass because the bow is much too light at this point. I'm willing to do that, but fiberglass seems really heave for the amount of stored energy it would add, compared to wood. Is there a drawback to using too much FG in a bow? for example, If i made a bow out of 100% FG, would be physically heavier or lighter than a wooden bow of the same design and draw weight? there must be a reaosn that FB laminated bows have wood in the middle. I'm assuming that wood gives more stiffness for its weight, while FG gives more stability and allows more extreme designs. Otherwise, we would see more bows made 100% from FG.  Right?

I'm still not sure about adding FG to this bow until i make sure that FG offers more stiffness for its weight. i want my bows as physically light as possible while storing as much potential energy as possible. I didn't want to use wood on the belly because the bow is reflexed, so i wasnt sure if wood would hold up at my desired 30" draw length. Horn or fiberglass seem to be the only viable solutions for this design since they resist compression better than wood (supposedly).

Offline PatM

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #10 on: January 07, 2017, 03:52:40 pm »
   Horn is stiffer than wood?

Offline tkdHayk

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #11 on: January 07, 2017, 03:56:28 pm »
   Horn is stiffer than wood?


it resists compressive forces better than wood as far as I understand, and prevents the belly from crumpling under compressive forces.

Offline PatM

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #12 on: January 07, 2017, 04:14:24 pm »
What types of wood do you have access to and how long is the bow? You might as well ditch the glass idea if you want more feedback on here.

Offline tkdHayk

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #13 on: January 07, 2017, 05:40:02 pm »
What types of wood do you have access to and how long is the bow? You might as well ditch the glass idea if you want more feedback on here.

the bow is around 60 inches and has a somewhat hinged limb design with the inner midlimbs doing most of the work as you can see in the photo.

I have access to hickory and bamboo "backing strips". But my goal is to make the best/fastest bow possible, so whatever material works better, Ill use it, even if its FG. Form my understanding, wood is stiffer than fiberglass for its weight, but breaks more easily. So ideally, i should have a wood core, sinew backing, and fiberglass or Horn belly. Do you think bamboo or hickory could really do the trick for the belly? keep in mind this bow is reflexed and will be drawn to 30 inches.
« Last Edit: January 07, 2017, 06:30:47 pm by tkdHayk »

Offline scp

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Re: reflex/static re-curve sinew/oak/fiberglass combo!
« Reply #14 on: January 07, 2017, 06:26:33 pm »
Depending on the total length of the bow and the desired draw weight, heat treated bamboo might work. As fiberglass is not allowed in this forum for philosophical reasons, you really need to try harder to use bamboo at all cost. If you only have bamboo backing strips, you might have to use more than one layer of bamboo. Good luck.