Primitive Archer
Main Discussion Area => Bows => Topic started by: ionicmuffin on March 13, 2013, 01:17:40 am
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So heres what i have. I have a 5 piece take down! lol. not really. but it is in five pieces. I was working on my red oak trade bow. (white oak was what i was using) i had heat treated and reflexed it after getting it to tiller because i had wanted to increase the weight. I was impatient and didn't wait for the bow to re-hydrate and wound up with an explosion. If it had survived i think it would have scared me to think it might blow in someone else's hands. I will admit that this probably was one of my worst boards ive ever picked. I have had trouble understanding what people are saying by "grain" such a controversial term.... anyway. I will be picking a new board or 2 from the hardware store when i have a bit of money. i drew black lines where the rings were. to my current understanding, this board was highly violated, and i also believe that this one is a "plain sawn" board. I did see a really decent board at the lumber store a few weeks ago, sadly i didn't pick it out. I will be hunting again for a new board before too long. I believe there are 2 reasons for failure. one, it wasnt properly hydrated, two the grain of this board was in terrible violation.
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That sucks man but yea that's why I don't do board bows
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i actually really like board bows, but the issue is finding a proper board. unfortunatly at the time i bought them they seemed great. now i realize that they are pretty much junk. i suppose i could have a fire >:D
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Well a bamboo or good hickory backing can hold together a board with many run offs
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thats true. i need to find a good backing then, need to find a good supply of bamboo. but either way, for the board bow trade i still need a new board
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Be judicious with the heat . Boards this time of year will already be very dry.That heat will go all the way through .Not likely to rehydrate in a 30% RH enviro after being heated twice. JMHO.Tic ,tic,tic. That`s the clock ticking on the deadline , not a bomb ;)
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Please take a few moments and take a look at my site. I go through board choice. Unless you understand the concept of grain you will have difficulty. Jawge
http://georgeandjoni.home.comcast.net/~georgeandjoni/boards.html
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The MC had nothing to do with that break....you coulda soaked it in a river for a month and it still Woulda snapped...that was doomed to break from the start because of poor choice in grain alone
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The MC had nothing to do with that break....you coulda soaked it in a river for a month and it still Woulda snapped...that was doomed to break from the start because of poor choice in grain alone
+1
I don't think the highly reflexed high stress design helped either. But in a way it did you a favor because it insured that the bow broke in your hands rather than eventually/inevitably in someone elses. I've never built a bow from a board so I don't really speak from experience but from the collective wisdom that I've gathered here, board selection for good grain is the first and most important factor in the success of a board bow and cannot be ignored regardless of backing or design considerations. Good luck on your next one.
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well, actually here in washington we have a rh of around 70% lol. i had already achieved full draw and more, so i strongly doubt it wouldnt have effected the bow. it was probably at 4% mc. Keep in mind it wasnt red oak its white. so i have a feeling that it would have taken a LOT more than red. ive had red oak blow for no apparent reason, where as ive never had white blow, this was a first, and the first time i didnt wait after heat treating. But of course i still accept the fact that the grain was poorly chosen.
like i said before. ill be working on finding good stuff, i had seriously seen something similar to http://www.primitivearcher.com/smf/index.php/topic,24411.15.html
the grain wiggle a tiny bit but the over all grain was strait. the grain went from tip to tip
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The worst bow explosion i've had the displeasure of being involved in (blew at full draw and i punched myself right in the nose) was on a WHITE oak board, that was a really good board...until it wasn't.
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im very fortunate to have sustained no injuries from the explosion. i think it could have been bad.
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any plain or flatsawn board is gonna have violations on the back, what you really need to look for are runoffs, on all four sides, check jawges site it will help you figure it out
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WHEW! That is nasty grain man. MC wasnt your problem at all. Im sure you've read a thousand times before grain is all that matters in boards, that is a true story. Adding a hard backing of any sort wont hold together bad grain either, or at least not for long it wont.
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it would be nice to understand the physics of why it wont work. im a sciency guy, so understanding that would help to see why and why it would blow so easily
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Its simple...the grain is violated......think of it this way...
The grain is like woven fibers or strands in cordage,rope,or cable....so take a 8 strand rope that has a lift capacity of 100 pounds...and take your knife and make a bunch of partial severed cuts in it...now go ahead and try to pick up 100 pounds with it...it will prob make a few lifts,but you know its not safe and is going to fail sooner than later
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i suppose that makes sense. Well either way. It blew and im glad it happened to me.
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I don't know anything about board bows lol but what i've heard is that if you don't pick the perfect board it'll break, ya can't get very high draw weights from them, and the biggest, they cost money. Why not just go cut a sapling and make a bow from it? It's free and has WAY less limitations. Idk just my opinion.
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well, i would, but this is for a trade thats supposed to be made of a board. My plan is to finish this trade and then to try to collect as many staves as possible. I also have a hard time finding good staves.
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Hey muffin man, Is there anyway you could take some clearer pics? If those are the grain lines ,I don't know how you managed to get it to bend like this before the final attempt at heat treating.(Not saying it's impossible,just couldn't do it myself) It should have let go long ago. The fact that it broke in 5 places at once? Scary. Glad you weren't hurt. I know the guys are saying the heat didn't do it , and I'm not saying it wasn't the grain ,but If it was the grain only , you shouldn't have been able to do this , even if the wood was green.(http://)All I'm saying is ,now you know the effects that heat treating has on a bow.(looks like you toasted it pretty dark btw) Good luck with the next one!
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in my opinion it wasnt grain entirly because it hasnt broken at ANY places in the grain! it was at solid rings where there wanst violation, thats whats weird
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Only bow I have had blow up on me so far has been a white oak molly and that thing went off like a shotgun.
Grady
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Not so weird muffin. Like I said on the other post , It'll likely blow if you cook it trying to raise the weight on this one. Already high stressed design ,heated once before (? I think),Oak, board (so it likely started out with a lower mc) .That's a lot of strikes against you. To get the belly toasted that much ,the back was nearly as hot when it's that thin. I've checked with a digital thermometer and with a real quick heat (just enough to start toasting with the gun about 1/8" away ) the belly starts to toast on oak around 200deg. and the back is at 160-180. I have also checked the weight and found that it looses quite a lot % wise but regains about 3/4 of what it lost and stops regaining after 2-3 hours.
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well, i guess i will have to do more research on heat treating and all that good stuff. every time i see it its done from farther away. oh well.
OH! and before i forget! let my failure serve as an example for others of what not to do! This failure to make sure i knew what proper grain was didnt leave me scarred but it could have left me blind in one or both eyes, it could have really messed up my head or chest, lungs, or arms. Please to all that want to do board bows. Look for grain that looks like this. This would be the back of the bow.
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Have you got another photo of the bows back that isn't blurred!? Maybe using natural light.
From what I can make out the board was quarter sawn. Those black lines you've drawn don't seem to correspond to anything I see in the wood. It sure doesn't look flat sawn to me.
Yes grain is a poor word to describe how the fibers run ;) 'grain' is ambiguous....
Think of wood fibers as being like rope, they are immensely strong when being pulled. Now imagine that you have lots and lots of them all laying parallel to each other.....but stuck together with weak glue.....they are still strong when untouched but as soon as you cut through a couple and then try to bend said piece of wood the 'ropes' will peel apart along the 'weak gluelines'. Why can you split a log with an axe on the end grain so easily???? Weak glue! Try cutting straight into the grain.....
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Just to muddy the waters a bit ,..................... the board you just showed could also have violated grain . Could even run off at 45degrees. It would just be harder to see. :( . If you have a knot in a quarter sawn or rift sawn board it will run across the face instead of front to back. Now imagine if that knot was in the board next to yours and didn't show at all in yours. You still have the grain that flows around the knot .
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I had a good little White Oak board bow on the go as well. But I just did not tiller it enough, it was around 65# at 27". Way to high, I pulled it beyond the point of no return and "SNAAAAPPPP" The grain was almost perfect, as good as any board I have ever seen.
Hasty is..Hasty does..!
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Bow101 - Could you post a pic for comparison and forensics?
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Bow101 - Could you post a pic for comparison and forensics?
Maybe at sometime, but the snap is about the same..
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Did the break follow the grain lines ? Did you heat it at all? MC?