Primitive Archer

Main Discussion Area => Bows => Topic started by: sleek on August 13, 2016, 03:45:05 pm

Title: Newbie sinew question
Post by: sleek on August 13, 2016, 03:45:05 pm
If a bow is cracked on the back, not a splinter but an actual crack that goes half way across the back, can a few courses of sinew safely allow the bow to shoot again? Its not going to be heavy, only 45 @27 probably and 56ish inches long, stiff handle. Also, if sinew will save the back, should I reflex it also to put more tension on the sinew, letting it press harder against the wooden back as it stretches? Or does sinew even work that way?
Title: Re: Newbie sinew question
Post by: Pat B on August 13, 2016, 04:07:09 pm
If the crack goes across the back the bow is virtually dead. How did it get a crack across the back?
Title: Re: Newbie sinew question
Post by: sleek on August 13, 2016, 04:14:09 pm
Ummmm well.... seeees its like this..... i get impatient sometimes and dont always round off my corners nefore bracing, annnnnnddddd it kinda cracked on a corner. Cause ima dumbass.
Title: Re: Newbie sinew question
Post by: wizardgoat on August 13, 2016, 05:54:51 pm
I wouldn't invest time in saving a bow with sinew.
I like my sinew bows to be designed for it from the start.
Always gotta round those corners man!
Title: Re: Newbie sinew question
Post by: sleek on August 13, 2016, 06:10:51 pm
Well.... i guess i will grind off tje back down below the splimter, then maybe sinew will help it. But when folks say, designed for it, how do you design a bow for sinew, what do you do differently?
Title: Re: Newbie sinew question
Post by: Pat B on August 13, 2016, 06:20:06 pm
Post pics before you do anything else.
Title: Re: Newbie sinew question
Post by: sleek on August 13, 2016, 06:27:05 pm
Ok. Im off to a store right now. I will when I get back.
Title: Re: Newbie sinew question
Post by: DesertDisciple on August 13, 2016, 06:33:31 pm
I'm by no means qualified to answer this, but I think by 'designed for' he means that you make a bow that will use sinew to improve performance, rather than as a safety buffer. I think this implies that the bow will usually be shorter and possible intentionally reflexed and/or reverse braced to make a snappy and hard hitting shorter bow out of woods that may not normally make a bow with those qualities, in those dimensions. I think usually you plan on having a significantly thicker and more crowned layer of sinew to completely remove the responsibility of tension from the underlying wood and let it worry more about holding the overall form and withstanding compression.

This is probably why juniper and ERC are such popular candidates for sinew backing. You are far more experienced than I in all matters, but this is what I've gleaned from the wisdom on this site. All that being said, I'm currently waiting on sinew to cure on a hickory bow that I almost sawed in half, and may be too short for the draw length and weight I want... compounded by the almost sawing it in half bit. I've sort of struck a happy medium between 'thin protective layer' and 'performance layer.' We will see what happens. LOL.

Title: Re: Newbie sinew question
Post by: mullet on August 13, 2016, 08:16:13 pm
TOAST. :)
Title: Re: Newbie sinew question
Post by: osage outlaw on August 13, 2016, 08:58:22 pm
I wouldn't invest time in saving a bow with sinew.
I like my sinew bows to be designed for it from the start.
Always gotta round those corners man!

I agree 100%.  If I'm going to sinew a bow it's going to be planned before I rough it out. 
Title: Re: Newbie sinew question
Post by: Stick Bender on August 14, 2016, 08:59:36 am
Sucks man I feel your pain I was just there 2 weeks ago all ready moved on !
Title: Re: Newbie sinew question
Post by: loefflerchuck on August 15, 2016, 12:20:21 am
No. The bow is broken. There is one thing you can do. Put a thick sinew backing on the bow, then remove all the wood from the belly, then glue a new wood belly to the sinew. Or just start over with a new stick.
Title: Re: Newbie sinew question
Post by: loon on August 15, 2016, 12:47:51 pm
if the crack is shallow maybe you can superglue it or use loctite 480 then rawhide back (I'd make it reversible expecting the bow to blow, to save the rawhide) and see what happens?

hornbow had a crack across the belly, maybe it was just the shellac layer, maybe not... used loctite 480, hasn't blown up. though the belly is different
Title: Re: Newbie sinew question
Post by: Pat B on August 15, 2016, 12:51:22 pm
If the crack is a splinter lifting along the edge you might be able to save it but it the crack goes across the grain on the back the bow is dead. A crack across the grain on the tension side is not repairable. IMO! How did it get the crack to begin with?
Title: Re: Newbie sinew question
Post by: PEARL DRUMS on August 15, 2016, 12:53:27 pm
If you are talking about that way too short of a bow you made a few months back? It wasn't a lack of rounded edges that got ya' there. It tore in tension because its over worked and too short for what your asking from it.
Title: Re: Newbie sinew question
Post by: sleek on August 15, 2016, 04:54:42 pm
Im gonna call the bow toast. It has snake character to it so I cant give it a wooden backing either.

Pearl, no, its not one of my shorties. This is just a regular d bow.
Title: Re: Newbie sinew question
Post by: PEARL DRUMS on August 15, 2016, 05:22:45 pm
Good decision. Grab another stick and do it again.
Title: Re: Newbie sinew question
Post by: sleek on August 15, 2016, 05:23:07 pm
Haha, i hope not pearl.

Lol your confidence in my ability to screw up seems warranted however.
Title: Re: Newbie sinew question
Post by: PEARL DRUMS on August 15, 2016, 05:26:37 pm
I meant build another one, not do the same thing twice!
Title: Re: Newbie sinew question
Post by: scp on August 15, 2016, 05:45:53 pm
Haha, i hope not pearl.
Lol your confidence in my ability to screw up seems warranted however.

That was funny. Of course he just wants you to try again and succeed this time.

Anyhow you are way ahead of me. I have been thinking about sinewing a bow for the last five years and still cannot decide whether I would "sacrifice" a perfectly good self-bow stave, even though I have dozens of them.

Good luck this time.
Title: Re: Newbie sinew question
Post by: LittleBen on August 15, 2016, 07:28:04 pm
I've only found on way to repair a crack like that.

I use a 4 ply linen string which I cut to a few inches long, and separate into it individual plies. Then glue them down carefully over the crack with superglue making sure they are all nicely aligned and they are in a single layer. Use superglue. Then saturate them in glue, and then feather the ends down smooth.
Title: Re: Newbie sinew question
Post by: mwosborn on August 15, 2016, 09:22:00 pm
I am not good enough at tillering to get a 56" stiff handled bow to pull to 27"!  IMO, the sinew should have been applied before tillering on a bow with those measurements.  With that being said however, I am kind of conservative.  ;D  Good luck on the next one.