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Author Topic: How much weight does sinew add?  (Read 8079 times)

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Offline coaster500

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How much weight does sinew add?
« on: June 09, 2012, 03:44:57 pm »
I've got a take down that I built that comes in about 41#s. It shoots very well but I was thinking about sinew to add a bit of weight. I could pike it a little but it is at 62"s now and I like the length.

Will sinew help with a 62" bow and how much weight would two or three layers of sinew add?
« Last Edit: June 09, 2012, 04:07:04 pm by coaster500 »
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Offline JW_Halverson

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Re: How much weight does sinew add?
« Reply #1 on: June 09, 2012, 03:51:07 pm »
The longer the bow, the less result you get from the sinew.  You have to "load" the sinew to a certain point to overcome the weight it adds to the limbs.  On longer bows your arc on the limbs is less than on shorter bows, the return on investment is just not there.  How long is the draw length?  Stiff handle or bendy handle?

You might need to pike an inch off each limb and add sinew to boot if you are looking for 50#'s of draw.  One really good layer on the whole bow (if you are good at laying up sinew) and another right down the middle of the limbs would give you a good 5-6 lbs, plus what the piking adds.
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Offline coaster500

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Re: How much weight does sinew add?
« Reply #2 on: June 09, 2012, 03:55:21 pm »
So how much would you pike it to get the most from the sinew? Is there any benefit to flipping the tips for the sinew or should I leave them straight?

sorry the draw length is 28"s for this bow...
« Last Edit: June 09, 2012, 04:01:23 pm by coaster500 »
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Offline PEARL DRUMS

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Re: How much weight does sinew add?
« Reply #3 on: June 09, 2012, 03:58:11 pm »
I believe it to be a perfect canidate for sinew. I would leave the bow as is and put 5" blocks under each tip. Tie the center down and add 2-3 layers of sinew. It will add well over 10# and give you a chance to scrape some compressed fibers away and start virtually fresh. The take down part is the tough part. That sinew matrix works together all across the length of the bow. Stopping it midway will negate some of the bonus, but still serve its purpose.

Side note: Flipping tip adds at least 3-6#'s.
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Offline Pat B

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Re: How much weight does sinew add?
« Reply #4 on: June 09, 2012, 03:59:58 pm »
It is hard to say. Depends on the bow, wood and design,and your local RH. You could get about
10# with 2 to 3 layers.
 Other options would be to kick the tips up a bit and tempering the belly.
  Ideally 2x your draw length would give you a good bow length for sinew.
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Offline JW_Halverson

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Re: How much weight does sinew add?
« Reply #5 on: June 09, 2012, 04:01:59 pm »
I just realized I don't know what wood you used.  Osage? 

If you got osage, you could pike it down to double your draw length and lay on the sinew.  My every-day-shooter is 52" nock to nock and I pull 26". 

With the 28" draw, 59-60" of bow would get decent reaction with the sinew.  The back of the bow would really start to resist tension and cause the plane of neutrality to move closer to the back.  You would, in effect, have more belly wood resisting compression causing the limbs to store more energy. 

But that's just my take on things.  Don't grab the saw just yet, let's get a few others to weigh in on the subject. 
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Offline coaster500

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Re: How much weight does sinew add?
« Reply #6 on: June 09, 2012, 04:05:14 pm »
The bow is Osage made from matching billits..  it is finished with tru oil with a flat spar finish. How would you remove this finish from the back of the bow?
« Last Edit: June 09, 2012, 04:09:42 pm by coaster500 »
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Offline PEARL DRUMS

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Re: How much weight does sinew add?
« Reply #7 on: June 09, 2012, 04:11:43 pm »
The amount of reflex is every bit as important as the length is. A short bow with follow still wont work the sinew as hard as a longer bow with ample reflex will. I have a 64" ttt sinewd osage flatbow with 2" of solid relfex at it shoots great. Im quite sure the sinew is working hard even at 64" ttt. Like J-dub, this is just my spin on it. None of us have done much lab testing!
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Offline PEARL DRUMS

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Re: How much weight does sinew add?
« Reply #8 on: June 09, 2012, 04:12:48 pm »
Easy does it scraper work is how I remove sealer Kip. You will see the white curls turn to yellow, stop there and finish with sandpaper.
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Offline coaster500

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Re: How much weight does sinew add?
« Reply #9 on: June 09, 2012, 05:14:54 pm »
Thanks guys I'll get at it next week :)
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Offline osage outlaw

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Re: How much weight does sinew add?
« Reply #10 on: June 09, 2012, 06:35:42 pm »
How is the fact that it is a take down bow going to affect the sinew backing?  Won't you have to stop the sinew in the fades?  I'm just having a hard time picturing this in my head at the moment.
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Offline gstoneberg

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Re: How much weight does sinew add?
« Reply #11 on: June 09, 2012, 06:48:15 pm »
I've tried a couple times to add draw weight with sinew and wasn't very successful either time. On the other hand bows I've designed from the start to be short, stressed and sinew backed are great. My honest opinion is that piking, flipping and heat treating will serve you better.  I will defer to Pearlie on adding reflex. I hate to tiller big reflex so I never do it. Perhaps had I done that things would have been better on my fix it attempts. However, my rule is that I only use sinew if I'm planning on it from the outset.

Good luck with the bow.

George
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Offline PEARL DRUMS

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Re: How much weight does sinew add?
« Reply #12 on: June 09, 2012, 07:38:37 pm »
Quote from: osage outlaw on June 09, 2012, 06:35:42 pm
How is the fact that it is a take down bow going to affect the sinew backing?  Won't you have to stop the sinew in the fades?  I'm just having a hard time picturing this in my head at the moment.

Clint I mesh my entire bow together when I sinew them. My first piece is right dead center with equal portions each side of center. Then continure on with that pattern. The whole bow worth of sinew is working as one. The two piece bow wont allow that.
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Offline osage outlaw

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Re: How much weight does sinew add?
« Reply #13 on: June 09, 2012, 07:46:47 pm »
So Coaster500 won't be able to add sinew to his bow?

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Offline PEARL DRUMS

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Re: How much weight does sinew add?
« Reply #14 on: June 09, 2012, 08:30:54 pm »
Sure he can. I just prefer to tie it all together. Sinew can still work split at the middle.
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