Breaking only the second board

Carol

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I agree with most of what you said, but I will disagree with this one part (bolded). 1 2" thick board is much harder to break than 2 1" boards put together - for the reasons you've given. It is much harder to make a single, thicker board bow than several thinner boards put together, even if they are strapped together.

He didn't say that the two boards are considered an equally thick board, however. He just stated that they are an extra-thick board. ;)
 

Kacey

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He didn't say that the two boards are considered an equally thick board, however. He just stated that they are an extra-thick board. ;)
But that's my point - 2 boards without spacers, while certainly much harder to break than 2 boards with spacers are not an extra-thick board. I've hit a 2" board, and it is not the same as 2 1" boards, for the reasons of physics that tellner stated. Breaking a 2" board is much harder than several 1" boards, because it is harder to reach that point where the board begins to deform.
 

Sukerkin

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Imagine the target is actually behind the 2nd board and completely follow through with the strike. Do not pull back on the power,

Exactly what I was taught way back when I did such things.

The same rule still applies now that I swing three-foot-razors around.

Always have the power focussed on a spot at a tad beyond where you think the sword will exit the target and you'll never suffer the embarassment of being disarmed by your own cut i.e. the blade is stuck in the opponent (how gauche :)).
 

Carol

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Breaking a 2" board is much harder than several 1" boards, because it is harder to reach that point where the board begins to deform.

One 2" board is much harder than several 1" boards? I honestly did not know that. Interesting!
 

Sukerkin

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This is actually a surprisingly fascinating topic - practical mechanics for martial artists :D.

I was just going to disagree with Kacey and say that two boards bonded together are stronger than a single piece but then I realised that in this case that is not true. With thinner boards, the bending moment is what causes them to snap, like tellner so elegantly expressed and Kacey elaborated on.

With thicker boards that bending moment is harder to achieve and you start to get into the territory of local pressure waves. That's a massively harder way to break boards as you have to crush, rend and otherwise mangle the cellulose fibres more directly.

To cite an example from past times (seems to be my night for recalling old events), I was having trouble breaking thicker boards because I couldn't get that useful self-deception "use ki to exceed your limits" to override my logic. The board was too thick to break in my minds image of physical reality.

After some coaching and some practise I had another go and stuck my fist through the board without breaking it (must've found a weaker area I reckon) - I didn't know whether to be embarassed with my new, somewhat unwieldy bracelet, or proud ("Hey look! I'm Chuck Norris!" :lol: ).
 

tellner

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Your caveats are good ones, Kacey. I certainly wouldn't say that two boards are equivalent to one board twice as thick, but the principle is basically the same.
 

Sukerkin

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Re-reading in the light of day, I think I need to clarify my last statement above as it gives the impression that I punched a hole through the board :lol:.

Tho' that's a cool image {Sukerkin Laser Hand Cookie Cutter Technique :D} it's not what happened.

What I managed somehow was to not quite break it but shoved my hand through the partial split as the board folded towards me and ended up trapped :blush:. Nontheless, and this was the somewhat hazy point of the 'original' anecdote, by focussing beyond the point of impact and striking to that point I managed to break what I previously couldn't.
 

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