Primitive Archer

Main Discussion Area => Bows => Topic started by: eastcreekarchery on October 30, 2020, 08:41:24 am

Title: Sinew vs rawhide backing
Post by: eastcreekarchery on October 30, 2020, 08:41:24 am
Which does better on a short, heavy draw weight bow?
Title: Re: Sinew vs rawhide backing
Post by: Pat B on October 30, 2020, 08:49:27 am
These are 2 different applications. One is primarily for performance (sinew) the other for protection(rawhide). Sinew can be used for protection but IMO rawhide is easier and more appropriate.
 For your situation, a short, heavy weight bow, I would use sinew, about 3 layers and hide glue.
Title: Re: Sinew vs rawhide backing
Post by: eastcreekarchery on October 30, 2020, 09:11:15 am
Ok thanks for the tip
Title: Re: Sinew vs rawhide backing
Post by: gutpile on October 30, 2020, 09:46:53 am
ditto Pat on this one... if for your cedar bow sinew is my choice.. rawhide will protect the back and thats about it.. sinew will protect the back as well and add performance by inducing some reflex.. I add sinew then hang a 25 lb weight from handle and have tips sitting on two chairs... I'll leave it like that for about a month... sinew will take a while to set up ... it can add poundage to a bow also... gut
Title: Re: Sinew vs rawhide backing
Post by: gutpile on October 30, 2020, 09:52:51 am
I'll add this also.. I draw around 26.5.. so I will longstring till my bow to about 19 to 20 inches prior to sinewing the back... and well before first brace... you want it sinewed before you brace it IMO ..especially cedar.. you just want to get the limbs bending fairly evenly before sinewing and with this method it will add more reflex than a roughed out bow ... gut
Title: Re: Sinew vs rawhide backing
Post by: eastcreekarchery on October 30, 2020, 10:05:23 am
I think im goin to use black locust for my short bow since my cedars are going to be quite knotty. I want a 22” draw so ill tiller to 15 inches then sinew back, let it cure and maybe try the 25lb weight method and then continue tillering.
Title: Re: Sinew vs rawhide backing
Post by: loefflerchuck on October 30, 2020, 11:30:05 am
Keep in mind black locust is not ideal for sinew as it is stronger in tension than compression to begin with
Title: Re: Sinew vs rawhide backing
Post by: gutpile on October 30, 2020, 12:02:59 pm
agree black locust must be tilled spot on or it will chrysal... I know not spelled right ..PAT !!! lol... I did a black locust short static recurve for my daughter when I first started building bows.. it survived luckily... still lives...but honestly not sure if the sinew hurt it or saved it  cause it took some set... gut
Title: Re: Sinew vs rawhide backing
Post by: willie on October 30, 2020, 02:10:55 pm


Quote
I draw around 26.5.. so I will longstring till my bow to about 19 to 20 inches prior to sinewing the back.

Gut, you tiller on the longstring to the intended finished draw weight? or some reduced amount of weight? Perhaps you complete quite a bit of belly tillering after the sinew is dry?
thanks
Title: Re: Sinew vs rawhide backing
Post by: bradsmith2010 on October 30, 2020, 02:24:32 pm
my short sinew back locust is good, I think the sinew reduces strain on the belly
Title: Re: Sinew vs rawhide backing
Post by: aznboi3644 on November 01, 2020, 10:44:04 am
Hmm.  I follow a guy on Instagram what makes some really nice short sinew backed black locust bows with 4oz of sinew on all his bows.  They are static recurved tipped and reflexed. Tiller is spot on but his hunting bows are great.  I do believe the sinew reduces strain on the belly,
Title: Re: Sinew vs rawhide backing
Post by: bradsmith2010 on November 01, 2020, 10:48:55 am
Ive never tried that much sinew, I will have to try that sometime
Title: Re: Sinew vs rawhide backing
Post by: gutpile on November 02, 2020, 07:40:02 am
willie... no I longstring just to get limbs bending evenly.. ..I can always reduce weight not add.... I get fairly close.. I never pull over my target weight either...this helps reduce any set I might experience..... If I'm shooting for a 60 lb bow I won't pull past that weight ...say I hit that at 17 inches I reduce the limbs at that point, put back on tree pull to 60 check till and see where I am at...   gut
Title: Re: Sinew vs rawhide backing
Post by: Allyn T on November 02, 2020, 09:16:13 am
So would sinew reduce belly strain because it raises the neutral plane much like perry reflex?
Title: Re: Sinew vs rawhide backing
Post by: mmattockx on November 02, 2020, 10:15:15 am
So would sinew reduce belly strain because it raises the neutral plane much like perry reflex?

Perry reflex doesn't do anything to the neutral axis, but you are correct that sinew lowers the belly stresses by shifting the NA towards the belly.


Mark
Title: Re: Sinew vs rawhide backing
Post by: Allyn T on November 02, 2020, 10:27:04 am
Then what does perry reflex do
Title: Re: Sinew vs rawhide backing
Post by: bradsmith2010 on November 02, 2020, 11:20:42 am
thats like a whole book,, i dont think I can explain it, some will chime in
Title: Re: Sinew vs rawhide backing
Post by: mmattockx on November 02, 2020, 12:50:23 pm
Then what does perry reflex do

As bradsmith2010 says, it is a large topic. Essentially, it preloads the belly into tension so that it does not experience the full strain from unbraced to full draw. The method of preloading the belly by gluing in the reflex also gets some work/energy storage out of the core material instead of having it only concentrated on the belly and back surfaces.


Mark
Title: Re: Sinew vs rawhide backing
Post by: Allyn T on November 02, 2020, 01:10:45 pm
I knew it allowed more of the core to do work but I thought that had to do with the neutral plane
Title: Re: Sinew vs rawhide backing
Post by: bradsmith2010 on November 03, 2020, 05:50:06 am
bottom line for me is ,, the bow will hold reflex with less mass weight overall,, so it shoots a bit harder for its draw weight,,
Title: Re: Sinew vs rawhide backing
Post by: Allyn T on November 03, 2020, 07:31:49 am
Brad which is simpler, perry reflex or sinew?
Title: Re: Sinew vs rawhide backing
Post by: gutpile on November 03, 2020, 07:50:06 am
simpler in terms of application... ?  perry reflex... lots of work goes into prepping sinew ... LOTS... not too mention dry time... sinew more primitive.. yep...sinew is primitive fiberglass... yes I said the f word here...LOL.... don't delete me...my boo backed perry reflex bows are screamers... gut
Title: Re: Sinew vs rawhide backing
Post by: mmattockx on November 03, 2020, 09:08:54 am
bottom line for me is ,, the bow will hold reflex with less mass weight overall,, so it shoots a bit harder for its draw weight,,

This is in favour of Perry reflex?


Brad which is simpler, perry reflex or sinew?

Perry reflex is far and away easier to implement. All it entails is gluing two pieces of wood together while holding the bow pulled forward into a reflexed shape, which can be as simple as clamping the handle to your bench and putting blocks under the limb tips.


Mark
Title: Re: Sinew vs rawhide backing
Post by: Allyn T on November 03, 2020, 09:40:01 am
Yes that's what I was asking, ease of construction.
Title: Re: Sinew vs rawhide backing
Post by: bradsmith2010 on November 03, 2020, 10:10:59 am
I dont know which one would be simpler,, :)