Primitive Archer
Main Discussion Area => Bows => Topic started by: k-hat on May 17, 2013, 04:32:12 pm
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Now that i have your attention >:D (it actually is quite graphic, you have to see a bow tortured and blown to pieces :'() In retrospect i hate that i did this test (sentimental value of the deceased), but if we can learn something then it's worthwhile.
There's been a discussion in another thread about the merits (or supposed lack thereof) of fabric (eg silk, linen, etc) backings. I have, well... had, a linen backed bow that i wanted to use to test the idea. I thought posting it on another thread would be useful because it gives some insight into the "controversial" uses of board bows, red oak, and backings.
Some specs and history:
Linen-backed Red Oak (linen painted brown because i didn't like the look), TB2 for the glue. This oak had very straight grain and about .8SG, a dream board. Dimensions as tested are:
1.75" wide parallel then tapering to about .5" the last 12" or so. (This was a Ferret's build-a-long bow)
ca64" ntn, 8" stiff handle, about .5" of reflex at the tips
History: This was the second bow i ever made a good while back, before i joined this site. The first was (intentionally!) a lighter version of the same for my son. As with most noobs however, this one came in underweight and had to endure my "fixitis". I forgot why i backed it with linen, probly all the suggestions of backing your first couple bows from the more experienced folk. Here's some of what she's been through:
*tempered in reflex after coming in under weight
*tempered again a couple more times (last deeply charring it) to try to raise weight (thinking perhaps i just didn't do it right the first time lol)
*mind you, all of these tempering sessions happened AFTER backing with linen (THAT'S A BIG NO NO!)
*piked a couple times to raise weight (again ::))
*found string out of alignment, so i redrew center and shaved off 1/4" from side of each limb and reshaped the handle to bring it close to center
*tiller is outta whack cuz after all this i never bothered to adjust it after making changes
I put at least a few hundred arrows through her during all of this, and kept hearing a "tick" on the draw and never figured out what it was until one day i sighted down the bent limbs and could see a boatload of splinters trying to raise under the linen. She's been in the corner ever since.
Here is a pick of just one of the splinters threatening to poke through the linen. It's still under, but scared me enough to retire her. There are many others along both limbs:
(http://i1216.photobucket.com/albums/dd374/k-hat/100_1724.jpg) (http://s1216.photobucket.com/user/k-hat/media/100_1724.jpg.html)
Was trying to get a pic of the frets (they are all over the belly on both limbs), but just a blurry pic of the charred belly (the REALLY dark stuff was scraped off).
(http://i1216.photobucket.com/albums/dd374/k-hat/100_1725.jpg) (http://s1216.photobucket.com/user/k-hat/media/100_1725.jpg.html)
Here she is at low brace (about 3", didn't feel like adjusting it cuz i wasn't gonna shoot it!)
(http://i1216.photobucket.com/albums/dd374/k-hat/100_1726.jpg) (http://s1216.photobucket.com/user/k-hat/media/100_1726.jpg.html)
This is at almost full draw, here 43#@27". Surprised she still had this much weight. You can see from these the tiller is way off!
(http://i1216.photobucket.com/albums/dd374/k-hat/100_1727.jpg) (http://s1216.photobucket.com/user/k-hat/media/100_1727.jpg.html)
CAN YOU GUESS WHERE SHE'S GONNA BREAK???
NOW the moment you've all been waiting for!! The video. I have a string tied to the nock point and gonna draw her back until she snaps. How far do you think she'll get??? Click to view the video (the "event" is at 44seconds):
(http://i1216.photobucket.com/albums/dd374/k-hat/th_100_1728.jpg) (http://i1216.photobucket.com/albums/dd374/k-hat/100_1728.mp4)
Here is the carnage:
(http://i1216.photobucket.com/albums/dd374/k-hat/100_1731.jpg) (http://s1216.photobucket.com/user/k-hat/media/100_1731.jpg.html)
This is the same spot i showed earlier, splinter still the same!!!! (it looks more raised but it's just a better quality pic)
(http://i1216.photobucket.com/albums/dd374/k-hat/100_1737.jpg) (http://s1216.photobucket.com/user/k-hat/media/100_1737.jpg.html)
The unbroken limb still showing about .5" of reflex and almost the same profile after going to 36"!!!!! :o
(http://i1216.photobucket.com/albums/dd374/k-hat/100_1730.jpg) (http://s1216.photobucket.com/user/k-hat/media/100_1730.jpg.html)
Thoughts, comments, and questions are welcome!
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So what does this say to y'all???
Quality of a board vs stave bow? Is there that much difference?
Is a linen backing worthwhile? That is, does it do something or is it just added weight? Is there a linen-backing myth here?
I know what i think, i wanna know whatchall think!
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I think its pretty impressive that it got to 36 inches after splinters had already begun to form. I don't think any unbacked board would take that kind of punishment after splinters had already started.
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My thoughts exactly slackbunny. It's also a testament to a good piece of red oak. I don't know of many bows that could be overdrawn by 8" and not take a HUGE amount of set. Even before the break i got it to about 34" and it had just started to make some splintering sounds. I'm tempted to get some good epoxy, patch her up and get'r going again lol ;)
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Curious where it broke? Which limb? I would have said right limb 6 inches or so from the fade, but it looks like it may have been the left?
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That's an impressive draw length. I've always been a firm believer in backing bows and linen is my favorite material. I've broken a couple that were backed, but like you said, it was a crack and not an explosion (and not 36").
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It looks like it broke along a grain runoff. Check the grain lines along the side. The splinter lifted at one end of the runoff and it came out on the belly side.
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You nailed it slimbob. Right limb where you said it. I thought for sure it would go where that biggest splinter was if anything, but as I said that part stayed in tact. I know it's not a scientific study, but it's hard to deny that a splintered-up bow would have held together through all that without the backing.
One of the reasons i added all the abuse to the tale is because there was a lot of emphasis on the other thread about perfect glue surfaces, sizing the back, etc etc. All that is good, but you don't have to do a perfect job to get some security/safety. I laid the glue down, wet the linen, rung it out, laid the linen down, slathered some glue on top, and let it dry.
I wonder how long it would have held on if i had done a better job on glue-up, AND not tempered the belly after putting the linen backing on there. I don't doubt that the heat affects the glue, i'm just saying we don't give good ole TB2 enough cred ;)
I strongly believe i could have put another 1000 arrows through that bow if i hadn't done this test.
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I'll take a look Pat, you're probably right, if you're talking about radial grain. The longitudinal grain was just about perfect on this bow. I realized after the fact that the rays (radial grain) were running at an angle on the back and sides (not steep, but certainly not parallel).
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Yup you nailed it Pat, good eyes! The break follows the radial grain from back to belly, and you can see the fracture runs parallel to the rays on the side when i hold the two pieces together.
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Linen backing sure doesnt seem like dead weight to me. It may not protect as well as a thick piece of rawhide or a wood or sinew, but it does offer some protection.
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The bow had a splinter lift under the backing. The board wasn't good enough to be a self bow and would have best been backed with a thin strip of hickory imo - no splinter would have raised then.
I'm a beliver in the saying 'if a jobs worth doing it's worth doing right'. I just don't think that linen is doing a job right - it's too much of a halfway measure to me.
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Blimey, if that had been tillered better you could have pulled it all the way back to the UK ::).
Impressive that it went so far before blowing.
Del
(I think it would have been better if it had the 'Jaws' music in the background.... :laugh:)
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Mike, dude! Nobody's saying that a hickory backing isn't better than linen. The board wasn't good enough to be a self bow??? It was severely abused and out of tiller! Could it have been drawn to 36" with a hickory backing without breaking?
Not everybody can get whatever materials they want when they want. You work with what you have. That's the way the primitives did it.
The only thing I was trying to determine was DOES LINEN PROVIDE A MEASURE OF SAFETY. I wasn't even sure how far this could go, but anyone who answers this question with a NO after this test is just being willfully blind. Nobody says you gotta use linen, but it's nonsense to say it's not useful. ::)
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Interesting post. I think there are points on both sides to this. A cloth backing does add a measure of protection and this ought to clearly show that. 36" in a splintered back! Still, better backings available than cloth. Kind of goes without saying as far as I am concerned, as there is better wood available than Red Oak...but if RO is what you got, RO is what you use. Ditto cloth backing. Testament to ones skills to make a weapon from less than perfect material. I think it shows the range of ones skills. Why make a bow out of ERC? Because you can.
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Surely the only way to say that this test was conclusive is to run it again using an identical bow (including a splinter the same size in the same place) without the linen backing.
Otherwise there's no way of knowing whether the linen did anything at all, or if the wood just gave up when it wanted to give up.
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If it was suppling a degree of safety how come the splinter lifted under it? Do you get where i'm coming from?
Is a bow that has splinters lifting on the back really a bow? Like I said I only like to do things to the best of my ability and I don't see a linen/silk/woven fabric as a truely safe way of backing a belly wood that isn't good enough to become a selfbow.
The 'primitives' would have used the best materials available just like any craftsman would. They knew what they were doing and certainly wouldn't have used substandard materials for a bow. A bow takes a lot of time and effort to make with stone tools - prime material to start with would have been the aim. If you gave a 'primitive' man a slightly dodgy grained board and some linen and a split stave i'm pretty sure I know which he would chose. We however have the ability to go and buy boards....fair enough...seems like a quick and easy way to make a bow...but (and it's a big but :) ) you had better know what to look for and understand the principles of how a backing works to be able to make durable, safe bows from boards.
Hey don't get me wrong I totally respect you for doing the test. Testing things to destruction is how i've learnt a lot of what I know about bows....and it's just plain fun :)
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Would it not be easier to use bookmatched wood to get a rough idea one backed the other not?
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When the quality of the backing is in question, should the selection of glue be given greater consideration?
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Interesting post. I think there are points on both sides to this. A cloth backing does add a measure of protection and this ought to clearly show that. 36" in a splintered back! Still, better backings available than cloth. Kind of goes without saying as far as I am concerned, as there is better wood available than Red Oak...but if RO is what you got, RO is what you use. Ditto cloth backing. Testament to ones skills to make a weapon from less than perfect material. I think it shows the range of ones skills. Why make a bow out of ERC? Because you can.
That's all I'm trying to get across Slimbob. If you don't have access to prime materials, you do the best you can with the best of what you have. To tell a new bowyer he's gotta use hickory cause linen is useless (besides being an erroneous opinion) is deflating and discouraging. When i started this a cheap lowe's board and linen from the thrift store ($1) WAS ALL I COULD AFFORD!! And i busted my but with nearly primitive hand tools to make this into a bow. Nothing i read at the time mentioned radial grain. When i came across the board in my early days it fit all the best descriptions (per longitudinal grain). I didn't even know what radial grain was at the time. So the advice to back a bow with "SOME MEASURE OF PROTECTION" is GOOD advice, as is seen here. It made up for my lack of knowledge at the time. Did i want a hick backing? YES, but couldn't afford it at the time.
Will, have you ever known a bow (without interlocking grain like hickory and some whitewoods have) to hold together even to full draw (much less overdrawn) when it already has erupted multiple splinters down the back? I haven't, but my experience isn't everyone else's. We act like a splinter is the death of a bow, then say well who knows if it would've held on?
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Interesting experiment, Khat.
If you look at the left limb the tiller is about as good as it can be. However, the right limb is bending too much right where it broke which is probably why it pulled up a splinter.
For me, because I am so fussy about board choice, the purpose of a cloth backing is to add insurance to a slightly less than perfect board. I allow 2 run offs per limb ... tops. If the board has more than that it gets eft in the store. I walk away.
I don;t know have many run offs the board had.
Jawge
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There were multiple splinters up and down both limbs as i recall (well, the outlines of them under the backing anyway). There was no splinter on the edge however where the break started before i overdrew it.
As for the grain, the longitudinal grain (the edges of the growth rings) was nicely parallel on back and sides. I don't recall it having any runoffs in that regard. Again the radial grain was about 20-30 degrees out of parallel, which i believe is what allowed the break.
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That side grain or radial grain is something George has been preaching about for years but nobody seems to get what he's saying until their bow breaks along its radial grain. ???
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yeah Pat I think that's where i first read about it was on Jawge's site. Course that was after i had made this bow. Been much more careful about my board selection since ;)
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Man...I knew the explosion was coming and I still ducked and covered as if pieces were gonna fly out of the screen at me! I'm sorry about the sacrifice, but I'm satisfied that the backing provided considerable protection. How much stuff got broke by shrapnel? Josh
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Not to deviated to much,I think that a less than perfect board can make adurable bow if made long and wide enough in the mid 40's range.been shooting this r/o for years
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Agreed bushboy :)
Gun Doc: Ya you could tell i jumped a bit when it happened. A couple things got knocked over but no biggie ;) Don't look too hard so you don't see my mess of a work table ::)
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The Side grain in a board almost seems more important than longitudinal grain - as the side (radial) grain is under more direct stress when bow is being bent, or so it seems to me. Bushboy - how does the side grain look on that board of yours? There is lots of grain run-off from left to right as we can see, but is there much grain run-off from back to belly?
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Not to misinform and endorse boards with bad grain orenitation and I hope it didn't come across like that!being said I have had failures with much better stock! I always take the time to go through as many choices as presented!I like to experiment and am no stranger to failures.I kinda regret posting the pics I have as not to give people a false sense of sercurity!the only point I wanted to stress was with decent tiller and design durable bows can be made.this bow is 65"ttt ,2"@ the fade pyramid ,mid 40's#
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I think the key for you're bow bushboy is that you chose a pyramid design. IMO that is a smart choice for a board like that if you're gonna make it into a bow. A pyramid board bow has runoff no matter what, but it seems the strain is more evenly distributed making it less likely to splinter. This would not be true with a parallel limbed bow using the same board.
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To tell a new bowyer he's gotta use hickory cause linen is useless (besides being an erroneous opinion) is deflating and discouraging. When i started this a cheap lowe's board and linen from the thrift store ($1) WAS ALL I COULD AFFORD!! And i busted my but with nearly primitive hand tools to make this into a bow.
Who told you that?!
An opion cannot be erroneous - it is only an opion eg. someones belief. If somebody said something was a fact then sure it could be an erroneous 'fact'.
My advice to a new 'bowyer' would be to put the leg work in and find the closest thing to a perfect piece of wood before you start. This needn't cost money in fact it's likely to save you money. :)
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Lol Mike ok, what i meant to convey is at best it's an opinion (ie linen is useless) and at worst it's just flat wrong. Anyone who denies that linen is a useful backing is blinding themselves to the facts.
The whole reason for the test was someone charged that "linen and titebond as a backing is a myth" and strongly contended that linen does nothing. That is just false, there's too much anecdotal as well as direct evidence to the contrary.
I know that this wasn't scientific in the sense of having a broad sample set and controlled variables, etc. BUT, common sense and experience come into play here as well. (A great deal of science is done outside of the "cookbook" method you all were taught in school. A 1000 controlled tests can never prove an idea absolutely right, but it only takes a single test to prove an idea wrong. I think this is very close to that instance.)
A new bowyer is just that, NEW! The advice given to back with linen on your first few bows is sound advice because a NEW bowyer may mistakenly make less than perfect choices in wood selection. They are still learning what to look for, what can and cannot be worked with, etc. , so backing with linen, silk etc "just in case" DOES provide the added security. Will it hold a bow together that's destined to fail? NO, but will it hold a bow together after lifting a splinter (or several!) YES!.
The real safety here is NOT the safety of the bow, but rather the safety of the person shooting it!
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Hi K Hat and all, just found your interesting thread....good test K.....now you have to test a similar piece of wood without a backing.....then you have an experiment... otherwise it doesnt say much...
maybe you could remove the backing from the other limb and repeat the test.? if it brakes under less strain you have proved the effectiveness of cloth backings
36" is impressive though...I suspect the linen did help
Dave