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To break or not to break, that is the question!
Posted by
A+ Slingshots
,
19 June 2010
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Hey Friends!!! Welcome to my new blog "Sawdust and Wood Chips."
I've recently had more questions and discussions about wooden slingshots than I thought possible. It seems we are all curious as to the safety of our wooden objects of affection. I originally wrote this as a response to a post question wondering if anyone (me or others) had ever done any fracture and breakage tests on various woods. I realized after I posted the response that it really deserved to be a blog entry instead of just a post, and that I'm sure I would have other thoughts about my designs, shooting tips and various other "bits and pieces" of diatribe, musings and hopefully some wisdom that I could share that others might just be interested in as I go along. So... here is the post, turned first blog entry from the owner and craftsman of A+ Slingshots yours truly pallan65!!! I performed tests on all my solid wood frames which included Hard Rock Maple, Birch, Poplar, Red Oak, side laminated Bamboo and Acacia before ever bringing them to market. The PS series is designed to be held with a high finger braced grip so to simulate that (albeit still not quite fairly, but I couldn't come up with anything better) I clamped it in a vise just up from the handle where the finger grooves start. I then used a looped paracord band attached to a Archery bow scale. My scale tops out at 60lbs but I continued pulling with all my might with my foot braced against the work table leg. None of my frames broke or cracked with this test!!! I always used a similar test (without the scale and in my hand) to "over-pull" as a strength test for any possible "hidden" weakness before selling them.
I have never found any of my frames to be weak, and since the unique design mitigates much of any "leverage" potential that helps as well. Also, not having a wrist brace greatly limits the strength of bands that can be used on it. Using a hammer grip is next to impossible on my frame as well so that's yet another safety factor.
Now having shared all that... each and every type of wood listed above can be broken with a direct fork hit from a 1/2" steel, or .44-.50 cal. lead ball ammo. How do I know??? My teen sons and I in recent testing have accomplished this feat when being inattentive or overly tired (although only with narrower fork catties like my small PS-1). None has ever resulted in any injury as the forks broke only when hit and thus went forward with the shot and expended it's energy without having any rebound back toward us. Still the events jarred our hands and scared us a bit!
The issue as I see it is not really "fork hit breaks", but rather "fork hit invisible cracks." While I have never experienced this, the scenario seems possible or plausible enough to consider.
This possible event goes something like this...
"Shooter in the heat of a hunt or whatever distracting fun, makes a small fork hit (or several) which he doesn't even notice or even dismisses. A while later he pulls back to fire and just at the moment of full draw an invisible hairline fracture caused by the previous hits gives way. The fork shears off completely and flies back into his face causing injury."
Bottom line... I believe my testing has shown the solid wood forks I make to be more than strong enough for shooting even strong bands.... but they or any solid wood fork will break from a solid enough fork hit from a hunting weight ball, and could possibly have an unseen crack and break at an inopportune time.
So... since I always say, "If you criticize and point out a problem, you should have ideas for a solution." Making slingshots in some other material other than wood is not an option I wanted to settle for. So I came up with two solutions.
First, solution "steel reinforced forks." In a private PM Joerg had mentioned it to me not knowing that I have already been working on the idea with several prototypes and tests. Wooden forks will break if hit enough so I did not set out to make them unbreakable (other wise we should all switch to only steel forks) but to make them safer in the event of a possible hit and break. 1/8" steel rod epoxied through the forks and into the handle a bit accomplishes the goal I had of keeping a fork from completely shearing off from a fork hit. They will still break and crack but not shear completely. I have tested them even by hitting them with a ball peen hammer while the fork is laid across two raised surfaces at the tip and handle causing a broken or cracked fork that remained intact with the handle. This enhancement is intended as an extra level of safety above and beyond industry standards.
Second solution, the laminated characteristics of Birch hardwood 12ply multiplex causes it to crack and splinter with fork hits instead of shear off and fail completely like un-reinforced solid wood can. So I have already begun to offer my slingshots in this material at the original prices in natural, and four progressively darker stains. Same great designs just a different material!! This accomplishes the same increased safety feature as steel reinforcing, but at a lower cost.
Both these reasonable options are now available from A+ Slingshots. I'm committed to producing quality wooden slingshots as safe as I possibly can. Wood is a wonderful classic and traditional material that we can all keep using if we are willing to make a few changes. I'm sure I'll make even more changes as necessary. I love the motto "Adapt and overcome!!!"
~ Perry
I've recently had more questions and discussions about wooden slingshots than I thought possible. It seems we are all curious as to the safety of our wooden objects of affection. I originally wrote this as a response to a post question wondering if anyone (me or others) had ever done any fracture and breakage tests on various woods. I realized after I posted the response that it really deserved to be a blog entry instead of just a post, and that I'm sure I would have other thoughts about my designs, shooting tips and various other "bits and pieces" of diatribe, musings and hopefully some wisdom that I could share that others might just be interested in as I go along. So... here is the post, turned first blog entry from the owner and craftsman of A+ Slingshots yours truly pallan65!!! I performed tests on all my solid wood frames which included Hard Rock Maple, Birch, Poplar, Red Oak, side laminated Bamboo and Acacia before ever bringing them to market. The PS series is designed to be held with a high finger braced grip so to simulate that (albeit still not quite fairly, but I couldn't come up with anything better) I clamped it in a vise just up from the handle where the finger grooves start. I then used a looped paracord band attached to a Archery bow scale. My scale tops out at 60lbs but I continued pulling with all my might with my foot braced against the work table leg. None of my frames broke or cracked with this test!!! I always used a similar test (without the scale and in my hand) to "over-pull" as a strength test for any possible "hidden" weakness before selling them.
I have never found any of my frames to be weak, and since the unique design mitigates much of any "leverage" potential that helps as well. Also, not having a wrist brace greatly limits the strength of bands that can be used on it. Using a hammer grip is next to impossible on my frame as well so that's yet another safety factor.
Now having shared all that... each and every type of wood listed above can be broken with a direct fork hit from a 1/2" steel, or .44-.50 cal. lead ball ammo. How do I know??? My teen sons and I in recent testing have accomplished this feat when being inattentive or overly tired (although only with narrower fork catties like my small PS-1). None has ever resulted in any injury as the forks broke only when hit and thus went forward with the shot and expended it's energy without having any rebound back toward us. Still the events jarred our hands and scared us a bit!
The issue as I see it is not really "fork hit breaks", but rather "fork hit invisible cracks." While I have never experienced this, the scenario seems possible or plausible enough to consider.
This possible event goes something like this...
"Shooter in the heat of a hunt or whatever distracting fun, makes a small fork hit (or several) which he doesn't even notice or even dismisses. A while later he pulls back to fire and just at the moment of full draw an invisible hairline fracture caused by the previous hits gives way. The fork shears off completely and flies back into his face causing injury."
Bottom line... I believe my testing has shown the solid wood forks I make to be more than strong enough for shooting even strong bands.... but they or any solid wood fork will break from a solid enough fork hit from a hunting weight ball, and could possibly have an unseen crack and break at an inopportune time.
So... since I always say, "If you criticize and point out a problem, you should have ideas for a solution." Making slingshots in some other material other than wood is not an option I wanted to settle for. So I came up with two solutions.
First, solution "steel reinforced forks." In a private PM Joerg had mentioned it to me not knowing that I have already been working on the idea with several prototypes and tests. Wooden forks will break if hit enough so I did not set out to make them unbreakable (other wise we should all switch to only steel forks) but to make them safer in the event of a possible hit and break. 1/8" steel rod epoxied through the forks and into the handle a bit accomplishes the goal I had of keeping a fork from completely shearing off from a fork hit. They will still break and crack but not shear completely. I have tested them even by hitting them with a ball peen hammer while the fork is laid across two raised surfaces at the tip and handle causing a broken or cracked fork that remained intact with the handle. This enhancement is intended as an extra level of safety above and beyond industry standards.
Second solution, the laminated characteristics of Birch hardwood 12ply multiplex causes it to crack and splinter with fork hits instead of shear off and fail completely like un-reinforced solid wood can. So I have already begun to offer my slingshots in this material at the original prices in natural, and four progressively darker stains. Same great designs just a different material!! This accomplishes the same increased safety feature as steel reinforcing, but at a lower cost.
Both these reasonable options are now available from A+ Slingshots. I'm committed to producing quality wooden slingshots as safe as I possibly can. Wood is a wonderful classic and traditional material that we can all keep using if we are willing to make a few changes. I'm sure I'll make even more changes as necessary. I love the motto "Adapt and overcome!!!"
~ Perry
It happened to me. The catty was sitting in my hand between shots, with a strong set of bands on it and looking whole, then, when I repositioned it the fork fell off. My heart dropped!!! My first thought was, what if that held just enough to get to full draw? Quite an unpleasant ending! Not to mention the edge that the wood has when a fork breaks off. All the fork breaks I have seen have an edge that looks like the edge of a napped flint rock. That will slice a person to the bone!!
The other thing that I think people seem not to consider is other ways that wood cattys can be weakened; drying out and simply being dropped. And dropped with out it being by our own hand, thereby unbeknownst to us.
Good job Perry.
I don't want to be or sound paranoid with the commentary, but the saying is true, "better safe than sorry".