# Solid Wood Boardcuts, Safe or Not?



## Henry the Hermit (Jun 2, 2010)

I routinely tell newbies to use a good grade of plywood for board cuts. Naturally, some have concluded that I am opposed to solid wood board cuts. I don't give this advice because I believe all solid wood slingshots are unsafe, but because people who are new to making stressed forms from solid wood usually don't have enough knowledge to safely select the wood and form to ensure it will be strong enough to withstand the stresses. I'm not a newbie, and have learned enough to make the occasional solid wood board cut, but when I do, I do not use those frames for powerful bands or heavy ammo.

If I wanted a powerful solid board cut, I would go to Flatband or Bunny Buster for a frame. They've been making them for years and know how to do it right. Perry of A+ Slingshots sells excellent solid board cuts, all of which have steel or brass reinforcing rods in the forks.

So, to sum up, solid wood board cuts CAN be safe, if you know what you are doing. Since most newbies don't, I advise them to leave the solid wood board cuts to those who do know.

Now, all comments and discussion on how to make safe solid wood board cuts are welcome.


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## Marnix (Mar 29, 2014)

Thank you again Henry. However, how does one become "not a newbie," I assume bunnybuster and Flatband had to figure it out as well, and how did they get started... I don't know..


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## Henry the Hermit (Jun 2, 2010)

The "newbie" label goes away with a little time. How quickly you become an old timer depends on how much time and energy you devote to learning. Neither label is derogatory. We later comers have a huge advantage over the old timers. They did indeed have to figure it out for themselves, but they and others are more than willing to share their knowledge and SSF is the best place on the web to pick their brains.


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## squirrel squasher (May 17, 2013)

A split frame with exotic hard wood has stood up for me. Chips when you get a forkhit, but nothing catostopic


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## Henry the Hermit (Jun 2, 2010)

Some hardwoods are tough enough, so long as you pay attention to grain orientation. A fine example is lignum vitae which was actually used for propeller shaft bearings on large ships until th 60s.I have a few cut out, but the wood is very difficult to work, so they are unfinished.


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## Lacumo (Aug 18, 2013)

I'm overly cautious on purpose. I deal with anything and everything that could cause any possible injury (regardless of how remote the possibility might be) on a preventive basis. I overdo it, but that's OK. I like being uninjured (so far) and I hope to stay that way.

The first thing I did when I started shooting last year was busting a perfectly good board cut frame with two fork hits inside 5 shots. Nothing was wrong with the frame, and the fault was all mine. At least I was consistent---the second fork hit was almost perfectly on top of the first one. That experience gave me a healthy respect for the possibility of fork hits causing problematic damage to board cut frames. Because of that respect, I'm wary of using board cut frames. Maybe some day when I'm a better shooter I won't need to be as concerned about board cut safety, but I'm just not there yet.

+1 on the split frame idea and +1 on the (hardest of the) hardwoods idea also, but I really prefer almost anything over a board cut. Solid plastic (HDPE or nylon), micarta, G-10, laminated (metal core=best), solid metal or really sturdy natural SS frames all make me feel more comfortable than board cuts.

If I was driven to make and use a board cut frame by the beautiful grain on a piece of wood or some other thing, I'd use >1" thick (ultra) hardwood and run metal rods through the forks and down into the handle just to keep my safety obsession from driving me nuts.


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## ash (Apr 23, 2013)

Well said, Henry. I regularly see solid wood boardcuts here that worry me with their poor choice of design at the weak-points. On the other hand, many are just fine and I make them myself quite regularly and have never had one fail.

Important things:


Choose a kind of wood that is not soft, brittle or prone to splitting
Make sure that the frame shape does not have any short sections of unsupported crossgrain (more explanation another time)
If you drop it or have a fork hit, test it extremely thoroughly before using it again

Here are some pictures to illustrate the weak points in typical frame shapes with typical grain orientation. The red line shows the approximate point where the load of the bands or the impact of a fork hit is likely to cause damage.

























This is because it is the location where the load is being distributed *across the grain* rather than *with the grain*.

Solid wood is far weaker across the grain, sometimes as little as 10% of the strength with the grain.

The best ways to strengthen this area are:


Make it out of something that doesn't have a grain all in one direction - plywood, laminate, HDPE, Aluminium etc
Laminate or pin - A cross-grain wood core, metal pins or dowels to support the cross-grain sections
Make it thicker - either along the red line (ie Whammo) or from front to back (ie Rambone)
Angle the grain - Natural fork or Wombat's split frame concept.

The frames pictured are all ply or laminated, so they're not prone to these problems. I wouldn't make any of these shapes in solid wood without taking some action to strengthen the red-line areas.


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## Marnix (Mar 29, 2014)

Thanks ash! Now, when we are talking about laminates, would cross laminating 2 or 3 pieces of the same hardwood be enough, or do I need to use different woods, plywood, or 8 or 9 layers...


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## ash (Apr 23, 2013)

Marnix said:


> Thanks ash! Now, when we are talking about laminates, would cross laminating 2 or 3 pieces of the same hardwood be enough, or do I need to use different woods, plywood, or 8 or 9 layers...


Three pieces is the minimum to get a safe balanced laminate. "Balanced" means it reacts to load the same from both sides and you're not going to get the cross grain piece cracking open unexpectedly. The outside faces should have their grain running straight up and down the frame, just as you'd expect. These pieces will take the main bending load from the bands to your hand.

The internal wood layer should be cross-grain - the grain running side to side (or plywood). This will hold the outside faces together in the event of a fork hit or similar impact. My rule of thumb for this inner layer is that it should be no more that 1/3 of the total thickness. Any more than that would tend to sacrifice too much of the thickness and strength of the outer layers. The middle layer is only there to support the outer layers. It doesn't do much load bearing under normal circumstances.

If you use four or more layers, it is possible and beneficial to angle the grain of each layer so that it aligns with the angle of each fork.

The more layers you use, the more they support each other in the event of an impact. Under normal circumstances there's not as much benefit, but impact damage is where board cuts usually go wrong, so that's what we're trying to help with. This is why 9 and 13+ ply birch is so highly regarded. If one layer cracks there are still 12 more to back it up.

In contrast, with a 1-piece board cut, once one tiny crack appears, it can easily make its way through the whole board without much help. With laminates, the crack will generally stop once it gets to the next layer.

.


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## ash (Apr 23, 2013)

Backing the truck up a bit...

You don't need to go all 13-ply, though. A boardcut of a well-chosen solid wood and sensible design is fine. The same with internal pins of up to 1/3 thickness that aid in holding together the cross-grain, are also good. As always, exercise caution after an impact.


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## Marnix (Mar 29, 2014)

Alright, so three 1/4 inch pieces is enough? Thanks ash for all the information!


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## Henry the Hermit (Jun 2, 2010)

Great info, Ash.


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## SlingshotMadness (Jan 17, 2014)

Ive had a Solid board break on me, but as Ash said, a stong piece and sensable design should be fine.


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## Individual (Nov 6, 2013)

I agree.

My bb shooter from Perry is made of Purple heart.

Its suffered 8ish fork hits and has only suffered dents and marks


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## crazymike (May 8, 2011)

the Question was solid wood board cuts,safe or not my answer is NOT


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## Djones02021985 (Apr 9, 2014)

I would love a Lignum Vitae slingshot to work on. That wood is incredibly strong. it's even used for high impact training Bokken (wooden samurai swords) for full contact training. love the stuff but hard to get hold of


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## benzidrine (Oct 14, 2013)

I recommend tying a thin rope from each tip of a boardcut slingshot and running the rope around or through a hole in the handle.

Then in the event of breakage the broken slingshot tip can't fly back and hit your face. It's what I did when I made board cuts.


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## Mr.Teh (Feb 28, 2012)

With the right wood i say YES !


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