Author Topic: Linen backing raising draw weight?  (Read 12180 times)

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Offline toomanyknots

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Re: Linen backing raising draw weight?
« Reply #15 on: November 30, 2010, 10:19:36 am »
@NTD

"The TBB's cover everything that you have brought."

This from volume 4 of the bowyers bible:

   "Combed linen will allow the impossible: putting woods back after too much has been removed. A 30lb bow can become a 60   
    pounder.  Not much thickness is needed either. About 1/16" on a typical limb will do."

"Do you build a lot of bows that take a lot of set?"

No, every bow I've ever built has 0 set because I'm perfect. ???

"The TBB's cover everything that you have brought.  How wood works and takes strain, how backings affect performance, how recurves work."

I like to talk about things. I also like to think about things. Aside from other things, this can be a good place for people from all over the world to think openly about things. Nothing I have ever posted has ever contradicted anything that of the authors of the bowyers bible has wrote. Yet you still refer me to it like I need to go reread it to "correct" myself or something? Calling my post on paleoplanet dogma was as well disgustingly irritating, as it proved you didn't even take the time to read it before putting me down. I suspect to inflate your own ego regarding knowledge on the subject matter, WITHOUT first acquiring knowledge of the subject matter. Telling me to shut up and be quiet was nice too. If you don't understand something in my post or it is beyond you, then please don't take your frustration out on me, as I have did no such thing to you.
"The way of heaven is like the bending of a bow-
 the upper part is pressed down,
 the lower part is raised up,
 the part that has too much is reduced,
 the part that has too little is increased."

- Tao Te Ching, 77, A new translation by Victor H. Mair

Offline Hrothgar

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Re: Linen backing raising draw weight?
« Reply #16 on: November 30, 2010, 10:42:03 am »
I have always assumed, without testing, that adding a layer or two of linen will add a pound or two to draw weight. Regardless, the main reason I back with linen is for insurance. I guess there are a couple variables to consider when using this material; for instance, the amount of glue (usually TB II) and number of layers. A couple years ago when I was making a lot of hickory-backed bows I noticed that on the occasion of a bow breaking it was never at the glue line but rather in the wood. Secondly, I've learned that when I apply linen (or rawhide, silk, etc.) that there is a moisture content in this polymer glue which can be absorbed back into the wood. In addition, because I first soak the linen, or  leather, or whatever in water to make it more flexible and pliable, I'm  deliberately exposing my dried, seasoned, wooden stave to new moisture. I"m convinced I've had at least one (hickory) bow develop set in a limb after I applied a couple layers of linen and failed to allow the wood to return to a low mc level before starting final tillering.
" To be, or not to be"...decisions, decisions, decisions.

Offline Kegan

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Re: Linen backing raising draw weight?
« Reply #17 on: November 30, 2010, 11:12:31 am »
Toomany- Two questions, first being what sort of linen did you use? You mentioned over on PP that you really stretched the backing out before applying. If it's a low stretch material already, it ight have had some effect- kinda like the silk backings people used to talk about. Second question, can we see some pictures :)? Alot of variables and it's easier to show than explain. Not to mention red oak boards  are unreliable jerks. But that's just my opinion O:)

Offline NTD

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Re: Linen backing raising draw weight?
« Reply #18 on: November 30, 2010, 11:16:14 am »
False dogma, TooMany!  You have made several unfounded, untested claims that if gone unanswered pose the chance of becoming the False dogma that was being discussed.                   You keep bringing up the combed linen ARE YOU USING COMBED LINEN?                          You are taking my comments from PP entirely out of their context and you know that.  It's certainly your right to take offense but none was intended and Tom saw it that way as well.  Have a great day TooMany!  I'm bowing out.           
Nate Danforth

Offline toomanyknots

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Re: Linen backing raising draw weight?
« Reply #19 on: November 30, 2010, 02:17:31 pm »
"first being what sort of linen did you use"

Linen fabric from Jo Anns Fabrics.

"Second question, can we see some pictures"

My sd card on my camera is fried, :( sorry, I would love to if it wasn't.

"You have made several unfounded, untested claims that if gone unanswered pose the chance of becoming the False dogma that was being discussed."

Specify.

"You keep bringing up the combed linen ARE YOU USING COMBED LINEN?"

No, I'm pretty sure on the paleoplanet post I made clear it was linen fabric. This is around the tenth time you didn't read what I wrote. I am sure you are only looking for something to prove some point you don't even have.

"False dogma, TooMany!  You have made several unfounded, untested claims that if gone unanswered pose the chance of becoming the False dogma that was being discussed."

Thats insane logic. How can a publically open debatable subject be dogma? I explained how backing a bow with a nonworking non stretching material could raise weight. If I made any claim you sure did not challenge it? All you did was call it dogma and tell me to shut up and be quiet, that in no way challenges anything I said. It just starts crap like this. Ironically I was challenging an idea that is very widely held to be true in the online community. I believe that is the definition of dogma. It doesn't matter anymore anyway as I deleted that thread before I got banned from paleoplanet for defending myself from nothing but a "UNFOUNDED CLAIM" about myself.

"Alot of variables and it's easier to show than explain."

True. I agree I would need to cancel out alot of those to be able to make a convincing argument either way. Which has not been done yet. So right now we will have to be satisfied with what we currently know, which is alot... Since saying anything that is not widely accept seems to stir up more than I want to stir up sometimes, I'm gonna stick with the basics:

1) Lets see what is widely accepted about all wood bows and how they work. A typical all wood bow's stress is divided between the back and the belly. The back is under tension and the belly under compression stress. The back stretches and the belly compresses. The most stressed points are the top most part of the back, which is under the most tension, and the top most part of the belly is compressed is under the most compression stress. I mean "top" as the most outside part, stress gradually decreasing until the middle point between the back and the belly is reached.

2) Now lets think about what is widely accepted about backed bows and how they work. It is said that some backings are strong, and some weak. Some backings it is said you cannot use on a compression weak wood, like sinew. As the backing could overpower the belly, hense chrysals. Now why would you get chrysals? If you bent the bow normally without the sinew, it would not of got chyrysals? But because you put the sinew on, it got chyrsals. Now how does that work?

 I think from a backing not allowing a bows back to stretch, that all the work in then forced to be done in the form of compression. A bows back does stretch when drawn. If it can't stretch, then that is just the more the belly has crush to bend. Your basically crushing the entire bow. This is why, as tim baker mentioned in preformance and design, flax due to it's resistence to stretching can  very easily overpower a bow. Because that is what your doing. Your crushing the entire bow. This makes alot of sense if you think about it. It just appears logical to me that this would raise the weight of a bow, thought I lack the ability to explain why forcing a bow to work only in compression raises the weight. But it does. Although it is slightly crazy NTD that you yell at me about how I need to go read the bowyers bible, and somehow ignore where tim baker in the end of design and preformance revisited volime four, where he talks about backings states exactly what I am saying,... 

"Combed Linen will allow the cliched impossible: putting wood back on after too much has been removed. A 30lb bow can become a 60 pounder. Not much thickness is needed either. About 1/16" of combed flax on a typical limb will do."

...Although thats crazy, it is even more crazy that you would up and not even read or try to understand anything in my post and yet still continue with your feeble claims, such as calling my post dogma. Please show me an unfounded claim in my point. Please show me dogma that I posted above me. Show me the dogma above. Show me how some unquestionable, religiously held belief (this is the definition of dogma if you didn't know that) can be drawn forth from an opinion? That logic would be insane.   
« Last Edit: November 30, 2010, 07:00:56 pm by toomanyknots »
"The way of heaven is like the bending of a bow-
 the upper part is pressed down,
 the lower part is raised up,
 the part that has too much is reduced,
 the part that has too little is increased."

- Tao Te Ching, 77, A new translation by Victor H. Mair

Offline PatM

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Re: Linen backing raising draw weight?
« Reply #20 on: November 30, 2010, 07:19:56 pm »
I would agree that simple linen cloth backing where only half the actual fibres are linear is not going to add much if anything to a bows weight.
 On the other hand a combed flax backing in any noticeable degree of thickness is essentially going to be like adding a reconstituted bamboo backing. That has to add weight. It's too stiff and dense a material when in a matrix to not do otherwise.
 If you added a thin layer of linen phenolic to a bow it will raise the weight and a well laid on Flax backing must  do the same since you are basically making phenolic in situ.

Offline sailordad

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Re: Linen backing raising draw weight?
« Reply #21 on: November 30, 2010, 07:30:25 pm »
well i was gonna stay out of this,but you know me and that wouldnt be like me would it  >:D

no i aint gonna say any thing negative or the like
what i will say is this

toomanyknots: do you have enough of that same fabric for another bow?if so then i would have to say
make another bow start to finish with out the backing,check the finished draw weight at the finsihed draw length
now after this has been done and recorded,apply the backing to the bow in the same fashion as previously on the other bow.
once the backing is dried recheck the draw weight at the same length and record trhe results.
then you and us will know for sure.
now you said it raised it 20# correct.if this is true can you get me the fabric brand name/style and sku and i will get some from my local Jo Ann fabrics
cause thats a serious increase in weight if its correct.
even if you dant make this bow,give me the fabric info and i will make one anc try it  ;)

                                                             peace,
                                                                    tim
i always wanted a harley,untill it became the "thing to ride"
i ride because i love to,not to be part of the crowd

Offline Badger

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Re: Linen backing raising draw weight?
« Reply #22 on: December 01, 2010, 02:01:05 pm »
I have backed several finished bows with linen. The draw weight gain was not all that noticable. Several years ago I used raw flax to add about 15# to a bow and it was thick! The draw weight went up but the performance stayed the same or went down, it was a real dog. Steve

Offline JW_Halverson

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Re: Linen backing raising draw weight?
« Reply #23 on: December 01, 2010, 10:42:19 pm »
Sailorday brings us back to heart of scientific discovery....duplication of results.  There will always be exceptions and erratic results, but if it can be duplicated then it can be proven. 
Guns have triggers. Bicycles have wheels. Trees and bows have wooden limbs.

Offline Hrothgar

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Re: Linen backing raising draw weight?
« Reply #24 on: December 03, 2010, 01:47:02 pm »
Scott, logic seems to suggest that by further twisting and tightening the cable would increase the weight and the cast. I plan on finding out this winter by making one with artifical sinew.  Have you seen this web-site?
www.primitiveways.com/cordage_backed_bow.html

" To be, or not to be"...decisions, decisions, decisions.

Offline PatM

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Re: Linen backing raising draw weight?
« Reply #25 on: December 03, 2010, 03:14:03 pm »
The article by Callahan mentioned documents a radical increase in cast after adding the backing cordage.

Offline Marc St Louis

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Re: Linen backing raising draw weight?
« Reply #26 on: December 03, 2010, 06:52:59 pm »
There was a young man from California that used to come here about 10 years ago.  He made a cable backed bow using Linen for the cable, I think he used Hickory for the bow.  Can't remember his name but his dad used to build bows as well and his name was Mark, the name might come to me yet.  From what I remember he used small blocks to raise the cable off the back of the bow and this method would raise the draw weight considerably
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