Wood question

[Nick]

OK, so I know that some of you guys have a bit of knowledge about more than just briar - unlike me. So that catapult my son and I made is way cool. We had to add a longer throwing arm. Unfortunately, all I has was plain of pine 2x4s. The longer arm got alot more distance, but the after the first few shots, it crack at the base, where the axel went through it. I got a new piece, added a block to either side for added strength, and we tried again. After 8 shots, the arm split at the base and totally snapped off the axel. No fun!

So, my question is what wood should i use? A search of the internet told me American Holly and Sycamore were good woods, but apparently hard to get in a size i could use (2x4 by 4'). The guys at woodcrafters said that Ash might be good, as its used for bows, but i wonder how that'll do with the big whack it'll get from when it hits the stop bar. Douglas fir seems easy enough to get, but I'm not sure how it'll hold up either.

So, any of you guys have a suggestion?

[Sasquatch]

Few woods are very resilient to smashing.... Fir or ash might be good, white oak maybe, and I wonder if you could protect it with a rubber sleeve or something.... some smash armour?

[Philthy]

Without a doubt hickory or Osage Orange (boisd'arc) as my first choices. Locust is pretty tough or maybe ash as a second chice.

[Patrick]

Yew wood is great for long bows if you can find a long piece.

[staffwalker]

White Oak, definitely. I'm old enough to have been around when things were made at the local shops. White Oak was used almost exclusively for anything where strength was required. Hickory was the second choice. You should be able to get a 2 X 4 of either at most lumber yards. bob

[smoorder]

the solution is not to add "strength", but to add "flexibility.
Look at the shaft of a hammer; one would recommend steel, because this is strong ... just try it and you 'll know why not
... or oak, or ebony .... all wear resistant, but brittle, so there's not absorbtion of vibrations ... and it snaps.

Ash and elm are a good choice.

You could reïnforce the hole with steel plates.
For the arm, you could try two "layers" ; make a kerf from top to 2" above the hole, and clamp together with bolts at both ends. No glue at all.
The middle section is able to move a little and this takes the stress out.
It 's not "stronger", but it 's able to sway a little more.
And a substantial cushion on the frame where it 's hit by the arm could make the difference.

[Sasquatch]

I use a steel hammer.

[Nick]

the solution is not to add "strength", but to add "flexibility.
Look at the shaft of a hammer; one would recommend steel, because this is strong ... just try it and you 'll know why not
... or oak, or ebony .... all wear resistant, but brittle, so there's not absorbtion of vibrations ... and it snaps.

Ash and elm are a good choice.

You could reïnforce the hole with steel plates.
For the arm, you could try two "layers" ; make a kerf from top to 2" above the hole, and clamp together with bolts at both ends. No glue at all.
The middle section is able to move a little and this takes the stress out.
It 's not "stronger", but it 's able to sway a little more.
And a substantial cushion on the frame where it 's hit by the arm could make the difference.

Thats why I thought Holly or Sycamore would be good. Both are shock resistant and flexible.

[wdteipen]

Good suggestions already made. One thing I would add as a possibility is to use a rubber sleeve where the shaft goes through the wood to help absorb some of the vibrations.