Primitive Archer

Main Discussion Area => Bows => Topic started by: make-n-break on January 22, 2018, 07:47:45 pm

Title: Backing big knots with burlap?
Post by: make-n-break on January 22, 2018, 07:47:45 pm

Hey guys and gals! It’s been a while since I’ve posted on the forum but I haven’t been slacking. I’ve been makin’ and breakin’ em but mostly posting my work to social media.  I’ll post a slideshow of recent work soon but for now I have a question that’s above my experience.

I have a straight and fairly tight-ringed Osage sapling that was about 3.5” in diameter. I’m decrowning it and I’ve cut through some pretty big knots. Anyone think a burlap backing will hold knots this size? I’ve had great luck with burlap on tight ringed Osage’s pin knots but never cut through any this big.

(https://i.imgur.com/I4P9V8i.jpg)

(https://i.imgur.com/cHrm12h.jpg)

Title: Re: Backing big knots with burlap?
Post by: bradsmith2010 on January 22, 2018, 07:57:22 pm

I dont think burlap gonna hold it,, but I have never tried it on a stave like that,, but I am scared (-S

Title: Re: Backing big knots with burlap?
Post by: Pat B on January 22, 2018, 09:38:47 pm

Why did you decrown it? 

Title: Re: Backing big knots with burlap?
Post by: Morgan on January 22, 2018, 10:56:42 pm

Why not a working back of boo or hickory since it is decrowned?

Title: Re: Backing big knots with burlap?
Post by: leonwood on January 23, 2018, 06:42:23 am

That would have been a perfect HLD stave if you left the crown;-) But now I would back it with boo or hickory!

Title: Re: Backing big knots with burlap?
Post by: make-n-break on January 23, 2018, 09:42:29 am

Pat - mostly for experimentation. I’ve only decrowned one other stave and I enjoyed the build. I thought this one was a good candidate because it was already small to begin with and had thick sapwood. By the time I got to the first ring, it had an arch comparable to a soda can. I still have the other half of the tree in the corner for a high-crown attempt.

Morgan - I do have some full length hickory backing strips. Might have to go with that instead!

Leon - I’ve seen your HLD bows. They’re incredible! Maybe I can muster up the courage to try it with the other half of this sapling.

Title: Re: Backing big knots with burlap?
Post by: Springbuck on February 10, 2018, 06:19:39 pm

"An arch similar to a soda can" as the crown would be about medium for me!   :-[ :-[ :-[

  For people blessed with more osage than I am, is there any reason osage wouldn't take that?

Title: Re: Backing big knots with burlap?
Post by: gfugal on February 10, 2018, 06:37:36 pm

burlap is jute right? which has a MOE of around 20-30 Gpa, but burlap is a fabric, and linen isn't nearly as stiff as flax fibers for some reason, at least according to the data I've seen. So, if you really wanted to shift the plane toward the back, and reduce the tension those knots feel, maybe you should get straight up jute fiber, or go for a stiffer fabric like linen (since flax has a MOE of around 40-50 Gpa), Or apply more of it. The discrepency between flax and linen fabric really has my head scratching. (40-50 for flax but like 9 for linen?) I think I need to study more sources for linen fabric. Maybe what they were using wasn't pure linen.

Title: Re: Backing big knots with burlap?
Post by: George Tsoukalas on February 10, 2018, 07:06:04 pm

No need to decrown. Leave it a few inches longer.
I know not it is too late.
There is an art to decrowning a stave. You have to violate the fibers equally.
The cut through knots are a definite death knell.
IMHO I'm scared of that stave.
I don't think burlap or anything will save it.
Be careful.
Jawge

Title: Re: Backing big knots with burlap?
Post by: Pat B on February 10, 2018, 07:16:01 pm

I've made a couple of osage pole bows with 1/2 of a 2" diameter pole, just removing the bark. They all worked out great. Osage can take a high crown.

Title: Re: Backing big knots with burlap?
Post by: Springbuck on February 10, 2018, 07:19:10 pm

Thanks Pat, that's what thought.