Sinew backing

[woodenwonder]

I just finished an Osage longbow 40# @ 28", 1 1/2" wide x 64" n to n. But then I dry heated a reflex/deflex curve in it. The dry heat made small cracks on the bows back. I removed the cracks by chasing down the outer ring. But now I have a nicely reflex/deflex 25# bow. So I want to add some sinew to bring it back up to 40-45#. I've read up on gluing down sinew with hide glue but I don't know how much sinew to use. Also I am not sure how long to dry it because I have heard several different lengths of time. Please advice.

[loefflerchuck]

For a bow that long and wide I would go for 2- 2.5 ounces of processed sinew. To bring a bow from 25- 45# with sinew I would want to let it cure for at least a month. If you are keeping the bow you can shoot it after a couple weeks but you may need to adjust the tiller a little after a couple/few months. With that much sinew you might want to do it in two sessions 1 week apart. Apply 2 layers and then a week later put on 2-3 more

[loefflerchuck]

BTW I have gotten those cracks from steaming and just put sinew over them. I also once left them and t5he bow shot fine and still shoots. To prevent them put a coat of shelac on the part your bending/steaming

[JW_Halverson]

I am not sure you have enough "meat" left on that bow to get the weight you are looking for. 

I would recommend you start a new bow.

[bowmo]

^ Likewise. I would have filled the cracks with glue and then put a rawhide backing over them. Buuut hind sight is 20/20.

[Danzn Bar]

Hey Wonder
I would not waste the sinew on that bow...sinew is too hard to come by  ....chalk it up to experience and start another like JW noted.  Sinew will not add that much weight to a bow.  Sinew works well on a short bow with a long draw length.
DBar 

[PatM]

Cut it down and then add the sinew.

[loefflerchuck]

Shorten your bow 6" and back it. That will be easier and use less sinew. I just finished a juniper bow with 9 layers of sinew. It draws 48-50# but the wood core is only about 25#. The bow it 46" ntn and draws 48 @ 23.5. It goes to 3 3/4" reflex right after it's unstrung.

[Danzn Bar]

Guys,
I think I learned more by starting over and using the sinew as it was intended,  believe me... I tried repairing and increasing poundage on a lot of bows when I started but learned its better to give the 25# bow to a kid and make a heavier bow from the beginning.  JIMHO....  
DBar

[Pat B]

Flatten the belly and add a osage or ipe belly lam. You'll have to re-tiller but I've dome this a few times with very good results.

[PatM]

Guys,
I think I learned more by starting over and using the sinew as it was intended,  believe me... I tried repairing and increasing poundage on a lot of bows when I started but learned its better to give the 25# bow to a kid and make a heavier bow from the beginning.  JIMHO....  
DBar

But if he cuts it down it's not the same as trying to bump up the same 25 pound bow. Cutting it down will get it most of the way there and the sinew will protect it and take care of the extra poundage.

[mikekeswick]

Of course he could get the weight up to 50# or whatever with sinew. What to bear in mind tho is that sinew/glue matrix has a specific gravity of around 1.3 s.g. ....and you will need a lot of it. You would also need to add a lot of reflex before and during sinewing which isn't the best idea once the belly has been to full draw.
If I had to use that 25# stave I would shorten a little, recurve the ends as much as possible and THEN add sinew. I would be using around 60 -80 grammes.
Like I said though in my eyes with the belly already having been to full draw....it's never going to be a rocket launcher!
Start another with the lessons learned 

[bradsmith2010]

yes if he cuts it down to a good sinew back length for his draw,, reflexes and sinews,, it can make a great bow,, I agree the 64 is too long for his draw with sinew,, even shot in,, a bow can gain weight and perform very well,, almost a rocket launcher,,,   so I would not start over,,no nead to waste a really nice piece of osage,, I would make the bow and see how she does,,, ,, I have made sinew bows from longer bows that were shot for years,,,and when cut shorter, reflexed and sinewed ,, shot very well,,,not much different than bows sinewed before tiller,,  I was curios so I looked up in my notes from 2004,, I had a long bow that I shortened and sinewed,, it went from 45@28 to 60@26,, and would shoot a 500 grain arrow 178 fps,, with a b50 string,(not a rocket launcher but good hunting bow for sure),the bow was about 10 years old when I revised it,,and is still shooting today,,20 years later

[dylanholderman]

while you guys are talking about sinew witch do you like better back or leg sinew? i had thought that back sinew was better because of its length, but the 3 rivers store said to use leg sinew for backing a bow.

[PatM]

 Leg by far.