48" osage shorty bendy handle recurve build

[stuckinthemud]

Hi Dave, just wondering why your photos can't be viewed in my region (the UK)?

[superdav95]

Hey gang.  Just a quick update on this little bow.  I am posting a short video link here for those interested in burnishing sinew covering.  Depending on how fast it dries in your area and climate will determine this.  Here in Alberta mine was sufficiently dry for me to burnish mi e smooth.  In the video you can see me showing a smooth piece of steel rod to do this.  I’ve done this with a coffee mug.  Anything smooth will work.  I also use thinned glue.  Some use warm water for this but I like the gap filling aspect of the thinned glue worked in.  It creates a very smooth and compressed top layer finish.  Sanding it down works too to give a smooth finish but this adds the benefit of compressing the fibers down. 

yes!  I just re read the entire thread its great.  I remember reading this years ago and and pats method here is really where I got the idea to use wraps in the first place.  I did try it btw and found it gave similar results as pat and others did.  I heated mine much the same way and ended up doing some experimenting with it after it was all said and done to get to what I do now with wrapped sinew.  Why did i make changes to this process??? 1. I found the diagonal wrap lines were hard to get rid of once dried.  it was somewhat doable with some work but not easy. the grooves were deeper in spots using the sheets.  2. it leaves a heavy crown.  If this is what you want then great but if it is not what your after then its hard to control the crown finish when dried.  The few ive done with this method i was somewhat able to control crown by heating and massaging with my fingers the sinew to be more flat but found it was a little inconsistent.  3.  the wraps did stick a bit on me. 

The great thing about Pats method is that its great for using up shorter sinew strands and controlling excess glue.

What I changed in Pats method.  I use horse leg wraps that are a little elastic and very thin to minimise diagonal lines in the sinew.  I found the bed sheet strips would stick to the sinew on me sometimes and needed repairs.  not a huge deal I guess but would rather not have to repair and rework.  the horse leg wraps have never stuck on me yet. not sure why that is entirely but it may have something to do with slight tacky coating on the wrap.   Im also able to work things a bit with my fingers still too while wrapped.  like the bed sheet strips it is also breathable.  In the beginning I would apply a little heat with my heat gun on low only and watch the excess glue ooze out a little if i think i may have used a little too much glue.  however these days though I don't heat it when wrapped as the last number of times nothing came out at all as far as excess glue.  I personally think there are some misnomers on the amount of hide needed.  in fact some sinew backed bows used zero hide glue other then maybe a few size coats on the back prior to sinew.  On these examples a few posted on here the sinew was chewed and softened in the mouth slightly to get soft prior to laying it down. no glue.  There is some thinking that the saliva generates a glue type matrix with the sinew to form a similar matrix as if glue were used.  this is a debatable topic for sure as ive only tried it once myself but i know others here on pa have made nice bows using the chew method.  My point here is that sinew needs far less glue then we sometimes think.  The addition of equal parts (mass in glue/sinew) is the rule of thumb for good ratio.  I have come to realize that this is not the case in my personal opinion.  in fact i have found that about a 1/3rd mass of glue to sinew is still very safe.  so how do i measure this??? Its hard to be sure but I do do my best to take notes and keep notes as to mass and weights start to finish.  generally speaking most of my finished bows with sinew backing have the original weight of the dry weight sinew plus approx 1/3rd for dry glue weight.  surprisingly sometimes less.  When fully dried Ive had no issues with sinew holding up.  Its strong stuff.  for a mental visual consider this,  I was making my strips to prepare for a bow and had laid out all my bundles like normal to prepare to be dunked in my glue and then laid down as normal.  I had finished backing the bow and had a bundle left over that i didnt use that was intended as a possible handle overlap.  My left over bundle had been sitting there all combed and shaped  and left overnight and dried.  in the morning i found the dried bundle had shrunk a bit and was very solid.  again i repeat no glue!  I could not pull it apart.  i could not bend and break it up either.  it was very firm and solid bundle.  I had posted about it here I think at the time and was surprised at how strong it was without glue.  Again to my point It may be argued that less glue is better if not at least a benefit to contributing less mass where its not needed.  Im sure there will be those that may disagree with this but I invite you to try and dry a clean bundle and see for yourself.  I ended up soaking the bundle and reuse on another project.  Im realizing this is a long answer/reply to your comment Willie!  anyway my point is that Pats method is an adapted version of what i do now.  when i clean and comb my sinew and dunk it into my glue i wring out most of the glue.  I also have used a small paint brush and put a light coat of glue as i comb the bundle and it also works.  similar results.  I let the bundle gel a bit before pulling off my shaping board to lay it down.  I use warm water only with a heat lamp sometimes to assist in shaping and blending.  Like pat I also lay the bundle and work in down with my fingers to rid the little crackling of air pockets that may exits.  once its barley gelled I add and thin layer of brushed on glue.  when wrapping with the horse wrap i again work it a little with my fingers.  this does not interfere with the wrap or it sticking to the sinew.  Ill leave this till the next day and unwrap.  The burnishing is the finish touch to get it compressed and very smooth.  anyway Pats method may give similar results in the end and maybe with more practice i would get better at it perhaps but i found the finished dried weight of the bow minus my sinew added was more then 1/3 glue mass added if that makes sense. It was more like 50/50.   sorry for the long winded response and thanks for linking Pats thread.  He was the inspiration for what I do now. There are more ways then one to reach the goal in the end.   cheers

ps,  Our alberta move involved us buying a home here and so residency was pretty quick. our health coverage overlap from Ontario took a few months but that was to be expected. 

Did you see the method posted by a fellow Ontarian? It seemed to come out rather smooth at the outset?  http://www.primitivearcher.com/smf/index.php/topic,43246.0.html

Just curious, How long do they make you wait before you can claim to be Albertan?

[superdav95]

Hi Dave, just wondering why your photos can't be viewed in my region (the UK)?

if you click the link i posted just below the description you will see pictures for you blokes in the uk.  lol

the program i use for hosting my resized pics imgr is not allowed in the uk i guess

[wooddamon1]

Pretty sweet, Dave!

[willie]

in the morning i found the dried bundle had shrunk a bit and was very solid.  again i repeat no glue!  I could not pull it apart.  i could not bend and break it up either.

this link points to the middle of a long conversation touching on multiple topics at the same time
http://www.primitivearcher.com/smf/index.php/topic,63182.msg888073.html#msg888073,
there is some historical evidence for twisted bundles used without hide glue and discussion of such in following pages in that thread

[superdav95]

in the morning i found the dried bundle had shrunk a bit and was very solid.  again i repeat no glue!  I could not pull it apart.  i could not bend and break it up either.

this link points to the middle of a long conversation touching on multiple topics at the same time
http://www.primitivearcher.com/smf/index.php/topic,63182.msg888073.html#msg888073,
there is some historical evidence for twisted bundles used without hide glue and discussion of such in following pages in that thread

Very interesting Willie.  I read through some of that’s stuff on sinew and chew vs hide glue.  The twisted sinew cable bow is also very cool.   

[stuckinthemud]

Thankyou for the link, it's a lovely bow.

[willie]

I read through some of that’s stuff on sinew and chew vs hide glue.  The twisted sinew cable bow is also very cool.

knowing you are an experimental and questioning kind of guy, I would ask....

do you have any ideas about how much sinew should stretch in order to add the most benifit?

or asked another way, how high or far away from the belly is optimal?

[superdav95]

I read through some of that’s stuff on sinew and chew vs hide glue.  The twisted sinew cable bow is also very cool.

knowing you are an experimental and questioning kind of guy, I would ask....

do you have any ideas about how much sinew should stretch in order to add the most benifit?

or asked another way, how high or far away from the belly is optimal?

Great question.  Preamble… I make these statements and claims purely based on my own experiences.  FWIW. 

BowEd and myself have discussed this topic together quite a bit.   How much sinew??? A general rule a thumb has been and continues to be 1/3 overall thickness in the case of a tri lam of sorts for the lack of a better term.  1/3 sinew thickness: 1/3 wood core: 1/3 horn for example.  This ratio works really well for a belly laminated bow with horn having wood as the core.  In other examples that are just 2 laminated sections like wood core only with sinew then this would depend on how heavy you want your bow to be I suppose.  Like any sturdy backing added to an existing bow it moves the neutral plane further towards the belly.  The neutral plane is generally in the middle of the bow limb but this can be manipulated with laminate backings or sinew or linen even on the back.  The same can be true with adding a belly laminate that acts as an increase in compression to move this neutral plane more towards the back.  Tension side failures are easy to spot and are often hard to miss with a lift or a violent break.  Compression is where the set is less obvious in the same way that tension failures are.  They can sneak up on us and show up as stress marks and crushed wood fibers.  Sinew added to a bow with no belly laminate I generally aim for 1/8” thickness.  This obviously varies a bit depending on the width of the limbs and where along the limb I’m measuring.  For example I will taper the thickness of sinew out towards the tips to keep mass light in those areas of the bow for better cast.  I’ll thicken it up on bending portions.  For reference the little Osage 48” bendy bow recurve I just sinewed last week I only added 50grams.  This may seem like very little sinew and may seem like it will make no difference perhaps.  My draw weight prior to sinew was 48lbs at 26”.  My goal and likely outcome with strategically placing sinew with the least amount of glue as safely as I can hopefully get 55-60lbs at 28” safely.  So the little added mass added with the sinew I estimate will get me there.  If this was a bow with a violated back or decrowned for example then 50grams would not be enough imo.   In the case of an already well tilled and shooting bow that the builder has maintained good build principles and not violated the outer ring then less is more to a point.  If the builder is merely looking for extra draw length with a margin of extra safety then it’s a good option.  I’ve built self bows in the past and backed with heavy layers of sinew and glue only to find it was slower then before.  Stability is another issue that gets overlooked.  I built a bow for a member here with out mentioning him by name where the bow had more sinew then the core would could control.  This particular bow build was a white wood bow and the target draw weight was too high or over estimated so I proceeded to scrape the belly to reduce weight.  In so doing the wood was about half the overall thickness of the bow with the sinew and the wood could not control it and became unstable.  Constantly needed correction and tweaking for balancing the limbs.  I then decided to add a thin belly lam of horn and it turned out great and moved that neutral plane where it was more stable.  So my advise to anyone wishing to add sinew to an already well behaved shooting bow that they just want a little more out of as far as weight and length of draw aim for approx 1/3 of overall thickness for a standard 1-1/2-1-3/4” wide limb out the fades.  On some wide limbed paddle bows or the like really the same sort of principle applies but it’s gets tricky to determine on some of those as far as thickness is concerned as there often more tapers and narrowing sections where no sinew may be needed at all.  For these measured bundles of wide strips of sinew bundles I find work well on the working part of the limbs.  As a rule of thumb on a hunting bow for example say 45-50lbs of standard flat bow or pyramid style 1/8” thickness of dried sinew layer is a good baseline.  The great thing about sinew is that if you screw it up you can always redo it sand it scrape it or add another layer to get it right.  You can’t really do this with any other backing.  So to sum up,  an all sinew bow doesn’t work for a reason because it’s not stable so putting the neutral plain somewhere within the wood portion of the limb is best for stability and balance.  The sinew will enhance the wood adding to it.    These are my opinions from my own experiences and experiments (so called)and from the input of many others along the way.  I learned from Ed and others like Arvin here the importance of taking measurements and keeping notes to assist with the best build.  I hope this somewhat answers your question Willie!   

[willie]

Like any sturdy backing added to an existing bow it moves the neutral plane further towards the belly.  The neutral plane is generally in the middle of the bow limb but this can be manipulated with laminate backings or sinew or linen even on the back.

Thanks for replying. There is indeed quite a bit to consider when working with materiels of different stiffnesses. 
I like to think that a laminate of two materiels of different stiffnesses, when bent, the neutral plane will move towards the stiffer side. It shouldnt matter whether the stiffer materiel is on the "back" or the "belly" or rather, which way the laminate is bent.

I’ve built self bows in the past and backed with heavy layers of sinew and glue only to find it was slower then before

Did this a bow have a long working length bend and have sinew applied thruout?

Sinew is wonderfull stuff that can stretch much more than other bow building materiels, but because it is not all that stiff, it needs to be stretched alot further to store the same energy as wood. Which is to say the most energy storing part of the sinew is furtherest away from the middle of the laminate.  If only there was a way to place the sinew even further away from the center of the bow limb.

[superdav95]

Like any sturdy backing added to an existing bow it moves the neutral plane further towards the belly.  The neutral plane is generally in the middle of the bow limb but this can be manipulated with laminate backings or sinew or linen even on the back.

Thanks for replying. There is indeed quite a bit to consider when working with materiels of different stiffnesses. 
I like to think that a laminate of two materiels of different stiffnesses, when bent, the neutral plane will move towards the stiffer side. It shouldnt matter whether the stiffer materiel is on the "back" or the "belly" or rather, which way the laminate is bent.

I may be thinking of neutral plane little different perhaps… in my mind the neutral plane would move the other way.  Towards the weaker side.  As an example take a bamboo backed hickory bow.  The boo strip will most definitely overpower the hickory if not made very this and appropriate tapers.  On early boo backed bow builds it took some experimenting to get this right.  I even had to trap the boo backing to even this issue out.  In my mind the neutral plane had moved too far towards the belly (weaker side) causing stress compressing fractures.  The sinew is great in that it is much less harsh to mitigate this issue.  It’s a more gradual softer transition than a hard backing like bamboo for example.  I hope this illustrates my point on this. 

I’ve built self bows in the past and backed with heavy layers of sinew and glue only to find it was slower then before

Did this a bow have a long working length bend and have sinew applied thruout?   Yes it was and it was in my early days of sinew backing and still learning.  Placing the sinew in the right spots like bending portions of limbs makes a difference in the cast of the bow.   I learned with each bow that I sinew.  And still learning. 

Sinew is wonderfull stuff that can stretch much more than other bow building materiels, but because it is not all that stiff, it needs to be stretched alot further to store the same energy as wood. Which is to say the most energy storing part of the sinew is furtherest away from the middle of the laminate.  If only there was a way to place the sinew even further away from the center of the bow limb.   Agreed!   It is great stuff and it turns a regular bow into something alive feel to it.  Almost magical.   

[willie]

Like any sturdy backing added to an existing bow it moves the neutral plane further towards the belly.  The neutral plane is generally in the middle of the bow limb but this can be manipulated with laminate backings or sinew or linen even on the back.

Thanks for replying. There is indeed quite a bit to consider when working with materiels of different stiffnesses. 
I like to think that a laminate of two materiels of different stiffnesses, when bent, the neutral plane will move towards the stiffer side. It shouldnt matter whether the stiffer materiel is on the "back" or the "belly" or rather, which way the laminate is bent.

I may be thinking of neutral plane little different perhaps… in my mind the neutral plane would move the other way.  Towards the weaker side.  As an example take a bamboo backed hickory bow.  The boo strip will most definitely overpower the hickory if not made very this and appropriate tapers.  On early boo backed bow builds it took some experimenting to get this right.  I even had to trap the boo backing to even this issue out.  In my mind the neutral plane had moved too far towards the belly (weaker side) causing stress compressing fractures.  The sinew is great in that it is much less harsh to mitigate this issue.  It’s a more gradual softer transition than a hard backing like bamboo for example.  I hope this illustrates my point on this. 

I’ve built self bows in the past and backed with heavy layers of sinew and glue only to find it was slower then before

Did this a bow have a long working length bend and have sinew applied thruout?   Yes it was and it was in my early days of sinew backing and still learning.  Placing the sinew in the right spots like bending portions of limbs makes a difference in the cast of the bow.   I learned with each bow that I sinew.  And still learning. 

Sinew is wonderfull stuff that can stretch much more than other bow building materiels, but because it is not all that stiff, it needs to be stretched alot further to store the same energy as wood. Which is to say the most energy storing part of the sinew is furtherest away from the middle of the laminate.  If only there was a way to place the sinew even further away from the center of the bow limb.   Agreed!   It is great stuff and it turns a regular bow into something alive feel to it.  Almost magical.   

as you mention, a layer of sinew 1/3 the total thickness might work out well with a wood bow without a horn belly. (I have no reason to doubt the experience of those who have built with sinew more than I have)
that said, limiting the use of sinew to the short working limbs of a lever bow might be a better placement for the magical stuff.
Have you looked at any crossections of turkish bows?
here are some pics of a chinese bow
https://atarn.org/chinese/visible_bow/visible.htm

[superdav95]

I got the coral snake skins laid down on this bow.  i used tb3 glue to lay this skin on.  worked well and just worked it down with my fingers and workedand air bubbles out the sides.  Its 2 different snakes actually the one was quite small so i spliced a section at each end. 

Link for pics
https://share.icloud.com/photos/0b5GOus3oKnU3v0KSEmfb8N9g


Heres a video link

https://youtube.com/shorts/gIzxKAHtbg8?si=nBV86Rb_llqL4e0W