16 replies to this topic

[wombat]

Strength of material seems to have come up again, so i thought I'd do a little testing of some of the wood I had laying around. Since I believe it's the 'shock-ability' of the timber that's important I came up with the drop test.The idea is to drop a 2.25kg sledge hammer from a height of 2.5 feet until the samples broke.
I'll let someone else work out the force.

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The samples were roughly cut 22mm wide by 135 mm long, although the timber is nominally called 18mm I've written the actual thickness on the wood as well as their species.

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The big surprise was the 30mm plywood/multiplex, admittedly it was just some cheap pine ply I still thought by doubling the 15mm it should have lasted longer!!?? No surprise with the Spotted Gum, It's the Aussie equivalent of hickory.....noted for it's toughness and shock-ability, this why they are both used for axe and hammer handles and why hickory was one of Rufus's preferred woods!

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This is just for a bit of interest and you can draw your own conclusions, and this is definitely not meant to be the be all and end all of testing wood.

[Hrawk]

Great post Wombat !

Isn't smashing things fun

I'n rather surprised by the marine ply though.

[wombat]

Hrawk, on 01 February 2012 - 08:24 PM, said:

Great post Wombat !

Isn't smashing things fun

I'n rather surprised by the marine ply though.

marine ply can be quite deceptive, it's manufactured more to be water, mould and fungus resistant. some are hard wood but these guys make their's from Hoop Pine!!! http://www.australpl.../pr_marine.html

[NaturalFork]

And you guys doubted my pine!!! Awesome tests. This is a great post. Thank you.

[Jaxter]

We have spotted gum trees in our backyard .

[Jesus Freak]

Like to smash things, it's so fun!

[Tex-Shooter]

Strength is important, but with board cuts breaks along the grain is the main consideration. That is why with a lot of the ergo designs Baltic birch or a laminate is the way to go. Hard wood is fine if you get enough grain length in the forks. -- Tex

[Btoon84]

great post. thanks for taking the time to do that. very simple test and the results were recorded well.

[hawk2009]

I have got my eye on some American black walnut hardwood timber does anyone know anything about it.

[Hrawk]

hawk2009, on 02 February 2012 - 01:04 PM, said:

I have got my eye on some American black walnut hardwood timber does anyone know anything about it.

http://en.wikipedia....i/Juglans_nigra

[Wingshooter]

This is a really good chart on different woods where you can compare.
http://workshopcompa...m#strengthchart

[wombat]

Wingshooter, on 02 February 2012 - 02:29 PM, said:

This is a really good chart on different woods where you can compare.
http://workshopcompa...m#strengthchart

it's a good little chart, but like all of them, there's no testing of 'shock-ability' hence my drop testing. but I was impressed with their explanation and pictures of the pedestal leg and the importance of grain direction, it's worth posting as a separate topic just for that!!

[newconvert]

ok so i will just throw this out there. by the excellent test wombat did it shows that similar sized woods or laminates do have a real shock value, although the test had no scientific info (not needed) the proof is in the pudding. so unless i am missing something here the plys are not necessarily more fork hit or break resistant than say hickory or spotted gum, i could go buy some lignum vitae and have a very strong light ss. or did it just fly over my head? i have been keeping my eye on wood types for a while for knife handles so i am familiar with the Janka tests.

[Wingshooter]

wombat, on 02 February 2012 - 05:32 PM, said:

Wingshooter, on 02 February 2012 - 02:29 PM, said:

This is a really good chart on different woods where you can compare.
http://workshopcompa...m#strengthchart

it's a good little chart, but like all of them, there's no testing of 'shock-ability' hence my drop testing. but I was impressed with their explanation and pictures of the pedestal leg and the importance of grain direction, it's worth posting as a separate topic just for that!!

Grain direction is the most important single thing in wood strenth. Ply wood is not nearly as strong as people think. Your test doesn't surprise me at all. A simple test of the strength of plywood is to cut a piece 1 inch wide 6 inches long and do the same with a piece of oak. Take the plywood and clamp it in a vise and take a large adjustable wrench and fit it to the top of the plywood and pull it toward you. It will break generally right at the end of the wrench now do the same to the piece of oak and you will see in a heart beat which is strongest. Remeber only half the thickness of the plywood's grain is running in the right direction for strength. That means only 3/8 inch on a 3/4 thick piece of plywood has the grain running vertical lets say while the rest is horizontal. The half that is running horizontal is as weak as balsa.
Back to grain you can make a very strong slingshot that will take a lot of abuse from plain old pine if the grain is running in the right direction.

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[wombat]

newconvert, on 02 February 2012 - 05:42 PM, said:

ok so i will just throw this out there. by the excellent test wombat did it shows that similar sized woods or laminates do have a real shock value, although the test had no scientific info (not needed) the proof is in the pudding. so unless i am missing something here the plys are not necessarily more fork hit or break resistant than say hickory or spotted gum, i could go buy some lignum vitae and have a very strong light ss. or did it just fly over my head? i have been keeping my eye on wood types for a while for knife handles so i am familiar with the Janka tests.

I might have opened a can of worms with the plywood failing so rapidly, but it was a cheap old piece of pine!! there are die hard fans of Birch plywood so I guess I'll have to try to find some. read wingshooters excellent reply above. as for the lignum vitae, you'll have a beautiful catty if your tools last, but it DEFINITELY won't be light, it's one of the heaviest woods available

[newconvert]

wombat, on 02 February 2012 - 06:58 PM, said:

newconvert, on 02 February 2012 - 05:42 PM, said:

ok so i will just throw this out there. by the excellent test wombat did it shows that similar sized woods or laminates do have a real shock value, although the test had no scientific info (not needed) the proof is in the pudding. so unless i am missing something here the plys are not necessarily more fork hit or break resistant than say hickory or spotted gum, i could go buy some lignum vitae and have a very strong light ss. or did it just fly over my head? i have been keeping my eye on wood types for a while for knife handles so i am familiar with the Janka tests.

I might have opened a can of worms with the plywood failing so rapidly, but it was a cheap old piece of pine!! there are die hard fans of Birch plywood so I guess I'll have to try to find some. read wingshooters excellent reply above. as for the lignum vitae, you'll have a beautiful catty if your tools last, but it DEFINITELY won't be light, it's one of the heaviest woods available

i am glad you opened this can, a little debate really gets the minds working, great stuff here, i know you are right about the lignum, but i sure am tempted

[Tex-Shooter]

Yep and that is why a natural fork is so strong. That is if it is not China Berry. -- Tex

Edited by Tex-Shooter, 02 February 2012 - 07:47 PM.