Primitive Archer
Main Discussion Area => Bows => Topic started by: Almostpighunter on August 09, 2010, 01:29:12 am
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Hey guys!
Here's a little fun for you and education for me (and maybe some others on this site as well). I made this bow about 1yr.+ ago for a guy I shoot with. It is boo backed, purpleheart bow with a bubinga pistol grip riser. When I went to the range to shoot today, the bow was waiting for me in this condition with a message for me to call the recipient. I called but only got his message box.
So here's the game:
If you are so inclined, take a look at the break and tell me what you think might have been the caused it. Some info not in the pics:
1. The bamboo is still in pristine, like-new, condition (so much so that I'm probably gonna re-use it).
2. There are no indications of chrysals anywhere in the purple heart, including in the area where the break occurred.
3. There is a weird looking burn along with what looks like shredded wood in the handle (pictured).
I have the advantage of having the bow in front of me and I am able to touch/flex the limb so I have a bit of an edge here and I'm pretty sure I know what happened. However, I do not want to influence your answers so let's hear some diagnosis' from all you bow doctors out there.
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high heat glue let go maybe ???
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It broke at a steep grain run off. Apparently the boo backing was too much for the purple heart belly and especially with the steep run offs.
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agree with above. grain run off looks pretty bad.i don't think i've ever had a bow fail that far out the limb.... i look forward to everyone elses idea on this.
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Allmost,
Looks to the old man in pic's #2 & #3 like a counterflex break, because the belly wood is blown outward like a tension failure.....my guess would be that either the bow was dryfired and/or broken string.....or option 2 might be manually counterflexed (bent the wrong way manually)
JMO since I aint got the thing to really look at.......just seems funny that the belly wood is split outward and not fractured like a compression problem.
rich
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That run-off should not have fractured in compression. My guess is that the bow was strung backwards.
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I think the scorched handle plays into this somehow...It sure is odd looking. Obviously the scorched handle didn't cause the break but I'm thinking what caused one cause the other...
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did he run over it?
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DING DING DING!!!! We have a winner...actually, "Winners!" Half-eye and Gordon both have identified what, upon close inspection, appears to be a counterflex break. What is tough to see from the photographs are the multiple smaller fibers that are exploding outward from the two major pieces as if the wood broke under tension failure as opposed to compression. Congrats to Half-eye and Gordon (and you boys win your choice of a cigar or a cupie doll) with honorable mention to Pat B as the break did indeed occur, for the most part, along the run off grain.
Frankly, I always felt a little patronizing when I told people who acquired a bow from me that one of the most important things to never do is bend the bow in the opposite direction (my layman's way of saying "counterflex"). It seems so obvious as something that would be detrimental to the health of the bow. And yet...
Anyway, let this be a good lesson to anyone who might be making a bow for another archer. Give them all the info you can on how the bow can, not only, be preserved, but about how the bow can be damaged as well. And rememeber, even if you do tell them everything...it doesn't mean they'll listen to you.
Oh, the burn...Actually NTD is right in that it wasn't directly involved in the break and it was more to confirm evidence of general misuse. Personally, I think there may be 2 potential explanations here:
1. The owner was thinking about either adding or carving an arrow rest (placement of the burn makes me think along these lines although I am at a loss as to the point of burning through the poly).
Or...
2. If the burn occurred around 4:20 p.m. it could have happened for another reason ;D and would also explain stringing the bow backwards ;D ;D ;D
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Damn, I got here too late, but I was going to say it was bent the wrong way... I was honest..hey guys..trust me I'm a Cat.
(And that grain run off is pants too)
C'mon guys it's 9AM here, I got here quick as I could...
Del
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Either one of Rich's ideas are legit. I have seen bows break like that when the string breaks and the tips just keep going. As for telling people not to flex it backward. You have to tell them everything or someone will do it.
Where did you get the purple heart? It doesn't look like true purple heart to me. Purple heart is usually darker with a lot finer grain than that.
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I was thinking that too Justin. It looks like ERC with a finish over it. ???
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Most of the boards I get come from a flooring supply store. Aside from the usual red oak at places like Home Depot and Lowe's, Vegas seems to be a relative wasteland as far as any bow building supplies are concerned (can't even find hickory easily). This is how I discovered purpleheart in the first place as it was an exotic looking board that was pretty cheap (about $5.99/board foot). The store itself is an absolute candy store for woodworkers with a great reputation; however, they DO seem to stock more product that is geared toward maximum grain exposure (it makes for more beautiful looking floor boards) so a thorough search and inspection of each board is required in order to find a grain pattern that is desired. In this case I knew I was backing the bow with the boo so I was a little more forgiving with the grain.
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Oh and I do believe the wood is purpleheart as it maintains its color throughout the board as opposed to just on the surface from a finish. Initially when it is rasped the wood color dulls a bit and turns a little brown, but as it rests the color comes back and turns that cool purple hue. Some of the deep gouges in the damage at the handle illustrate this and if I were a better photographer, or computer wiz, it would have been more visible.
@Pat: Sorry I may be having a brain cloud moment, but what is ERC?
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ERC is Eastern Red Cedar!
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I've never done a wooden or a backed bow but if I were to don one I would make sure the backing material is straight grained. Jawge
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@Pat: Thanks for clearing that up. ;D . Also, I reassure you with absolute certainty that the wood was Purpleheart and not Cedar.
@George: I completely agree, but the bamboo was the backing material not the purpleheart.
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Oh, sorry but that belly wood is pretty bad too. :) Jawge
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that wood looks identical to some mahogany that i have. and like del i got here too late
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@Ken75: Mahogany is right on! The way it was explained to me (and I am only repeating what I was told, I'm no expert) was that you start with Mahogany, and then season (somehow) the wood for twenty five years and you get Purpleheart wood. I never bothered to check to see if this info was correct, but if what I heard is true, then it would make sense that the grain pattern would look like your Mahogany.
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i have access to a six foot high and four foot wide stack of south american mahogany so of course i tried it for bows several times .it has always seemed extremely brittle i use it for overlays but stopped trying to put in bow limbs . just not as good as other woods i have . sorry bout your bow it looked nice
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Mahogany and Purpleheart are two very different woods.
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Okay, all this apparent controversy over Purpleheart has prompted me to get off my lazy a$$ and look the friggin info up. Here's what I found and is confirmed by several different sites.
""Purpleheart" is the trade name for about 20 different species of wood in the genus Peltogyne. Exotic Wood Group's Purpleheart belongs to the species paniculata. Purpleheart wood (regardless of the species) is very hard and dense, with an average specific gravity of about 0.86, and requires sharp tools for cutting.
Native to the tropical rainforests of Central and South America, Peltogyne paniculata trees grow to heights of about 100 to 150 feet, with trunk diameters reaching thicknesses of up to 5 feet..."
"Allergic reactions to Purpleheart dust can include skin irritation and/or nausea. Of course, as when working with any wood, adequate ventilation, as well as skin, eye, and breathing protection, are paramount. Although the heartwood is a dullish brown when freshly cut, it changes fairly rapidly to a vivid purple. Over time, with exposure to ultraviolet light, Purpleheart will inevitably darken to a brownish color. This process can be slowed, although not completely stopped. Ah, such is life. To prolong the length of time that the wood remains a lustrous purple, it's recommended to periodically apply a UV-resistant finish to the completed piece."
So there is the true origin of Purpleheart. I was misinformed about the Mahogany thing. I guess the only real way to tell if what I bought was "true" Purpleheart is the fact that the purple wood turned brown when I freshly cut/rasped it and then changed back to purple as the "true" species is want to do.
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The purpleheart I work with doesn't turn brown when worked, rasped, sawn etc...
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AAAAAAGHH!!!! I give up!