# Wood Selection, Safety, And Being New



## Pappybows (Sep 7, 2012)

OK, having read a bit here before and after my first slingshot build, I kinda figured some here knew first hand that wood selection, or base material, "is" of a safety concern. I did read that. I had already cut out and was shooting my first trial shot out of Peruvian Walnut, though. Having first hand knowledge of it, the wood, I knew I might have messed up by what I was reading here on lighter woods and what wood I used.

Well, shooting some light ammo and having a few fork hits, I could see the damage mounting, though nothing structural and I did build it thick. Still, I kept the thing low and away from my face. Tried out some heavier ammo today, bigger rocks, and first hit - whammo!

OK, now for any newbie who might wonder how important is what folks say here in regards to safety!

Viola:


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## ruthiexxxx (Sep 15, 2012)

A very important warning! I'm new to making slingshots but was a whip maker for years. The situation is very similar in that materials are subjected to extreme stresses. I soon leaned that anything that can go wrong WILL go wrong in the end and the only solution is to factor in BIG safety margins !


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## Hrawk (Oct 25, 2010)

An excellent read and valuable resource can be found here:

http://www.woodweb.c...ndbook/Ch04.pdf

In particular, Table 4-3a.

The three main points of interest for me when selecting a timber to use are:
Modulus of Rupture
Modulus of Elasticity
Sheer Tension Perpendicular to Grain
For those criteria, I specifically look for:
Modulus of Rupture - *Greater than 100,000*
Modulus of Elasticity - *Greater than 10,000*
Sheer Tension Perpendicular to Grain - *Greater than 5000*

For anyone interested in making their own slingshots or any woodwork in general, have a read of this chapter. There is a wealth of information for the new and experienced alike.


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## DracoUltima (Jun 14, 2011)

Try hardwood plywood. That stuff is crazy strong and will NOT break. You can ask some members around here on where to buy the stuff.


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## Pappybows (Sep 7, 2012)

Thanks, Hwrak! I have also used the Wood Database search function by name or species: http://www.wood-database.com/wood-articles/database-terms/#bending for similar. Thanks for narrowing down some of the properties for slingshots.

Ruthie, correct! From my reading here shortly after I haf cut it out, I should have assumed Murphy was to pay me a visit on this wood at some point. I now know more and know better and can plan in more redundancy for the next.


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## jskeen (Feb 7, 2011)

I'll toss this in as an example of what not to do;

http://slingshotforum.com/topic/6024-awwwww-crap/


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## All Buns Glazing (Apr 22, 2012)

Bad luck, mate. That being said though, I've killed a hardwood slingshot before (Shorea) with a 9.5mm steel ball with a single hit.

Unless the wood is extremely strong (like the one that was replaced with the Shorea break), I don't personally trust wooden boardcuts to survive much abuse, especially if you get an unlucky shot or a hidden 'flaw' in the wood.

Plywood is amazingly strong - but it's not particularly beautiful - so a lot of folks here make their own laminates or put a metal core inside. Solves that issue.

Myself? Give me a bandsaw and a chunk of 18mm, medium grade plywood


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## NCLeadSlinger (Sep 18, 2012)

Hrawk said:


> An excellent read and valuable resource can be found here:
> 
> http://www.woodweb.c...ndbook/Ch04.pdf
> 
> ...


This should be a Sticky......


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## Rayshot (Feb 1, 2010)

Hrawk said:


> An excellent read and valuable resource can be found here:
> 
> http://www.woodweb.c...ndbook/Ch04.pdf
> 
> ...


In seeing all the info you, by way of your posts, have investigated, I do believe you are a brainiac. That is a compliment.


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## Pappybows (Sep 7, 2012)

Thanks, all, and jskeen, I do believe your thread was one I had read and started my doubts on my material used. OK, to sum my understanding, the safest approach is either using a high-grade ply, making a ply of cross-grain - using good wood and at least 3 lams, or, laminates over metal frame. A natural fork seems strong enough and is acceptable, but as for board cut lumber, well, the single grain orientation dictates that most standard cuts will make for a weaker fork stem. Here, you really need to pay great attention to wood selected and grain orientation.


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## Henry the Hermit (Jun 2, 2010)

Again, advice I give to all newbies. Use plywood for your boardcuts. Unless you really know what you are doing and how to select the proper wood (I don't), the chance of a broken frame is just too high with solid wood board cuts.


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## Incomudro (Jan 12, 2012)

I haven't built any of my own, but if I did - I would either use a plywood of some type, or at least laminate two or more of my own wood layers together.
Having one grain run up through the forks is asking for trouble.


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## wombat (Jun 10, 2011)

I did some destructive testing awhile ago on a few bits of wood I had lying around.It sounds like it's time for a revisit, here.
Interestingly enough since I did the oringal posting I've tested a couple of others and one them was south american walnut, it scored a paltry '3' on the wombat scale. Bear in mind that SA walnut is quite different from the NA black walnut which I understand to be quite tough.


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## Pappybows (Sep 7, 2012)

Wombat, great test! On the Peruvian Walnut, I would be surprised it got much of any rating you assigned based on the whole of woods tested. But, like any wood, walnut is not all the same just because it has "walnut" or whatever in the name - many species - same generic name. The same happens in many woods, like red oak, where there is one true red oak, but in lumber-yard sense, many different trees make good red oak lumber to sell.


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