sinew backed ash bow?

[jasper]

I have a ash bow that has been tillered and is 66" long (tiller not perfect but losing weight) .  It has given me some problems and would like to pike it to 62" and sinew back it to increase weight and strength.  Is this a good length or should I go shorter to get the full benefit from the sinew.  My other question is ash o.k. to sinew?  It is white ash and a pyramid design.  Thanks

[Pappy]

It will work fine,you could cut a little shorter if you like,How much weight is it and how much do you want to gain.And also what is your draw length ?
   Pappy

[a finnish native]

tell us your draw lenght first. a sinew backed bow should be twice as long as the dezired draw lenght for example for 27" draw the bow should be 54-56". in this case the sinew will not add unwanted mass to the limbs and thus eat up cast from the bow. sinew backed bows thoughout history have been made to be short and I truly think we should rely on that information from our ancestors.
Remember also that tillering a sinew backed bow is about 100% more accurate and precise than with a wooden bow, because a sinew backed bow will fin even a small weak spot and start bending from there in time. happened to my sinew backed bow also. A few days ago a weak spot accured on the lower limb after 9 months of hard shooting! here's the link http://www.primitivearcher.com/smf/index.php/topic,1946.0.html

I feel that sinew is not a way to compensate the flaws of the wood. If you want to make a sinew backed bow with excellent cast and so on you should search for only the best type of wood. and then put plenty of reflex into it. If a sinew baced bow gains string follow it loses all of the benefits of sinew exept for the max draw lenght. also the cast will dissapear to a level of a not so good selfbow if string follow accures. Here is an example of an excellent sinew backed bow that has held reflex for 10 years or so http://www.primitivearcher.com/smf/index.php/topic,3166.0.html   
note the amount of reflex on that bow. a bow with such desing holds it's reflex more than 10 times better than a simple D bow.

[jasper]

My draw length is 26".  I want  it to end up somewhere in the upper 50's as far as weight.  Right now it is somewhere around mid 40#s at about 24".  I saw a place that just starting to hinge alittle and inorder to correct it remove more would and in turn lower the weight.  I thought I would try sinew on this one as practice since I got 40 some deer tendons last year and would love to do a short osage bow.

As far as cleaning and degreasing processed sinew, How do you do that?

Thanks for the info.

[Pappy]

It is close to 46 at 26 now ,if you cut it off to 62 you will pick up 8/10 lbs. at least so
if the hinge isn't to bad you can still hit weight,if you just want practice I guess that is ok but I would do it on something I was pretty sure of,It is a lot of work and sinew ant that easy for me to come by.That's just me.
    Pappy

[a finnish native]

If you mean dried sinew that is still in whole and the colour something like brown and NO white in the middle then you just pound it with a hammer against a wooden table etc and tear the "fibers apart of it. a good way to do this is to first split it in half and then those half's to half's and so on until you have about 2-1mm(millimeter) thick strands. if it is only just been taken from the leg then you let it dry on a board or something else. if it is already ripped to those thin white curls you might want to weigh it. I would not use sinew if I have it for under 60 grams.
the next step is to make bunches of about 15-20 strands. define the bunches so that you put the log strands in the same bunches and the short ones to their one bunches. After this you take the bow and make sure that it will not tip over. first heat treat the bow or by some other method put it so that it will have 3-5 inches of reflex when putting on the sinew.you can also put the reflex in so that at first there is somewhat 2" of it and then along the sinews drying time put more of it slowly. even up to 5" of reflex.
now to the gluing part. you take a bundle of those strands and then dip it into water so that it gets soaked (the temperature does not matter) then you pull it between your fingers so that excess water drips out. after that dip it into your hide glue. It must be about as warm as your hand. a little warmer, but if too hot it will lose all of it's gluing potential. about 40 centigrade is good. after dipping the bundle into the glue you do the same procedure than with the water and put it evenly on the back of your bow. (start from the handle and move towards tips) glue the sinew in a pattern like a brick wall is built. remember that towards the tips the amount of sinew should decrease due to its high mass. then after the first layer is done start the other one and glue the bundles on top and "between" the first layers bundles. thus you will get a nice crown and round back from the sinew.
put on the bundles made of the long strands first and then move to the shorter ones layer by layer. you will end up with some excess sinew which is perfect to be used in filling any "gaps" in the back. after all is glued you want to put a layer of hideglue on top to give a smooth appearance. at first when you are done and the sinew is still wet and white the layer will seem to be very thick. even up to 2/3-3/4 of an inch. don't worry about this. the sinew will shrink dramatically when drying. also note that it would be good to wrap the sinew over the tips to the bellyside to prevent it from slipping too much to the handle when drying. do not  dry it in a hot place, but in a normal temperature. This when using hide glue.
It would be good to let the sinew dry for a month or so. it might seem dry before but the glue and sinew are still getting harder and more tough.
Yup it sure is a lot of work!