Primitive Archer

Main Discussion Area => Bows => Topic started by: Jakesnyder on July 21, 2018, 08:33:40 am

Title: Sinew backing
Post by: Jakesnyder on July 21, 2018, 08:33:40 am
I am fairly new to making bows but have made a few and want to try my hand at a sinew backed hickory shortish bow. I have some staves but they are not fully dry yet. (My moisture reader read around 12%) I am wanting to rough it out and get it floor tillered. So my question is can I apply a couple of layers before the bow is completely dry or do I have to wait till it gets to about 8% to start applying the sinew?
One thing that making bows has taught me is patience and sometimes it is best to wait than regret it later on. But I wanted to see what some experienced bowyers had to say about it.
Title: Re: Sinew backing
Post by: Pat B on July 21, 2018, 09:48:34 am
You can add sinew now as long as the tiller is OK. You'll have be sure the wood and sinew are drier before stressing the bow. You'll add more moisture to the wood by adding the sinew.
Title: Re: Sinew backing
Post by: Jakesnyder on July 21, 2018, 10:00:16 am
Ok and i cant heat treat the belly after the sinew is on right? If I sinew back it should I worry about heat treating the belly?  Hickory is a little weaker in compression than tension right?
Title: Re: Sinew backing
Post by: Pat B on July 21, 2018, 10:38:06 am
The sinew will help relieve the belly stress but if you want to heat treat the belly, do it before you add the sinew.
Title: Re: Sinew backing
Post by: RandyN on July 22, 2018, 11:16:54 am
Like Pat said heat treat the belly before the sinew goes on. Don't forget to seal the belly  after heat treating, before putting the sinew on.
Good luck
Title: Re: Sinew backing
Post by: JW_Halverson on July 22, 2018, 11:36:34 am
Like Pat said heat treat the belly before the sinew goes on. Don't forget to seal the belly  after heat treating, before putting the sinew on.
Good luck

Tell me why you would want to seal the belly after heat treating and before applying sinew.  I have always felt it was best to leave a newly sinewed bow as UNsealed as possible to allow the new moisture more opportunity to leave the wood. 
Title: Re: Sinew backing
Post by: PatM on July 22, 2018, 02:25:39 pm
Like Pat said heat treat the belly before the sinew goes on. Don't forget to seal the belly  after heat treating, before putting the sinew on.
Good luck

Tell me why you would want to seal the belly after heat treating and before applying sinew.  I have always felt it was best to leave a newly sinewed bow as UNsealed as possible to allow the new moisture more opportunity to leave the wood.

 There is some thought that sealing the belly will prevent longitudinal splits from developing as the backing shrinks.
Title: Re: Sinew backing
Post by: JW_Halverson on July 24, 2018, 06:55:30 pm
Like Pat said heat treat the belly before the sinew goes on. Don't forget to seal the belly  after heat treating, before putting the sinew on.
Good luck

Tell me why you would want to seal the belly after heat treating and before applying sinew.  I have always felt it was best to leave a newly sinewed bow as UNsealed as possible to allow the new moisture more opportunity to leave the wood.

 There is some thought that sealing the belly will prevent longitudinal splits from developing as the backing shrinks.

OK, fair enough. Since they do not effect performance, I would not worry. I have never had belly splits on a bow I have sinewed. I do have an osage that was built at 52", 52 lbs draw at 26 inches, inch and a half at the fades.  And those belly checks go all the way to the sinew!  Some of the checks are wide enough you can stack up to 7 playing cards in the cracks!  Hehehe, ate a lot of venison off that bow!
Title: Re: Sinew backing
Post by: Mark Smeltzer on July 24, 2018, 11:03:53 pm
If you heat treat the belly and then sinew you will most likely be retillering the bow and removing the heat treated belly.
Title: Re: Sinew backing
Post by: Aaron H on July 25, 2018, 09:48:37 am
If you heat treat the belly and then sinew you will most likely be retillering the bow and removing the heat treated belly.
Unless you balance it using side tiller.

Personally, I would tiller out to 24" or so, then heat treat, then sinew nice and even limb to limb, then finish balancing it using the side tiller approach.   

Expect to gain a significant amount of draw weight with the heat treat and sinew (depending I the amount applied)

To answer your question though, I think you would be fine to go ahead and work the stave now just as long as you give it several months to dry after sinew
Title: Re: Sinew backing
Post by: trail walker on July 26, 2018, 09:20:37 am
so can the bow dry to much while you dry the sinew in the western climates? because i have sinew backed bow that is finishing curing. do i just lather it with oil or fat until it quits absorbing it after the sinew drys?
Title: Re: Sinew backing
Post by: Jakesnyder on July 28, 2018, 05:48:28 am
Is Pennsylvania too humid for a sinew backed bow? Would a polyurethane finish seal it to where the sinew is not effected?
Title: Re: Sinew backing
Post by: Pat B on July 28, 2018, 06:48:56 am
All you can do is slow down the hygroscopic rate with different sealers but you can't eliminate the moisture. If you keep the bow inside your house with a/c  while not shooting it you can keep it drier.
Title: Re: Sinew backing
Post by: Jakesnyder on July 28, 2018, 06:59:53 am
What is the best sealer to use for that?
Title: Re: Sinew backing
Post by: Marc St Louis on July 28, 2018, 07:12:56 am
I wouldn't seal the belly after sinew backing.  There is no logic in thinking that sealing the belly will prevent the wood from splitting.
Title: Re: Sinew backing
Post by: Jakesnyder on July 28, 2018, 08:11:42 am
Does anyone know if Pennsylvania works for sinew back bows?  It's not as humid out here as south east.
Title: Re: Sinew backing
Post by: Jakesnyder on July 28, 2018, 08:12:08 am
Will one last out here?
Title: Re: Sinew backing
Post by: Pat B on July 28, 2018, 10:33:34 am
I live in the southeast(western NC) and have made a few sinew backed bows. They work well but you have to keep them in a dry area when not used. I use Tru-Oil for all of my bows and on hunting bows I give the Tru-Oil finish a quick spray of satin poly to cut the shine.