How much weight does sinew add?

[Pat B]

The first couple of sinew backed bows I built I only put sinew on working portions of the limbs, not the tips or the handle. They all took set in the handle area. I think it is important to make the sinew backing "matt" all one piece through the bow, limbs and handle. The tips on the other hand I don't think need sinew and it will only add extra physical weight to the tips without any performance advantage.

[MWirwicki]

I wrote an article in a German magazine about 15 years ago about sinew backing. 
In the article I stated, "I disagree with backing a bow with sinew as a remedy for a poorly built bow."  (Not to say Coaster, that yours is poorly built.)   If I wrote it today, I would add, "for a bow that turned out light."

I also went on to say, "Backing a bow with sinew should be intentional.  It should be done for the purpose of building a special bow with unique requirements.  A considerably shorter bow that still allows the same draw length and weight of its all wooden counterpart." 

I've sinewed a bunch of bows since then and still agree with my statement of yesterday.  Again, not that yours is poorly built.  More times than not, the "fix" doesn't turn out as you hoped.  Sinewing should be part of the plan from the very beginning.  What I'm trying to say is, be happy with the bow you just made and chalk it up to experience and learning.  To this day, I make bows that come out lighter than I wished for.     It happens.  If you just can't stand it, do what I do...give it to a kid.   

[coaster500]

This is interesting and I may do it just to find out how it works with the takedown. I've got enough sinew prepared to do this bow and the Ishi type yew I'm working on (it was planned for sinew)....  just thought it would be cool to add a bit of weight to the takedown as I did miss the weight a bit.

You guys have got me thinking 

[mikekeswick]

 Here is what I would do.
Cut to 60 ntn.
Recurve the tips, short and sharp recurves.
Heat treat it into as much reflex as you dare osage can take a lot.
Crown the back if it's flattish now. Even it if fairly crowned then excentuate the curve by rounding the edges.
Sinew it. You want the finished back to be nicely crowned. With most of the sinew running down the center - this way you save on weight and get the most out of it.
Then have fun trying to string it for the first time
A while ago I did this process to on osage bow I made before I understood the materials properly and got quite a few extra fps out of it.

[mikekeswick]

http://www.primitivearcher.com/smf/index.php/topic,29960.15.html
This is the bow and i'm just off to a 3d comp shooting it

[Pat B]

I totally agree with Matt's thinking and writings. This should go for any bow building process. If you want a selfbow, build a selfbow. If it comes in under weight or whatever, mark it up for experience and make another using that experience. This is how we learn.
  After my experiences with not having the sinew backing one continuous layer through the handle I am curious how using a take down system will affect the overall performance of the sinew. Can each limb be isolated from the other and still give max performance that is expected from a sinew backed bow? 

[PEARL DRUMS]

Its a curious thought for sure Pat. I think it could as long as the handle area was wrapped and secured well so the limb stayed "loaded" when the two halves are seperated. I would like to see a few built and see what happens. Its really so hard to measure and know with all natural stuff. It just varies too much. Suppose thats why we all agree to disagree so friendly like huh?