auntlisa1103
Orange Belt
Which way do you crown the board on the blocks for a hand strike? I always forget.
Iām testing to first dan this weekend!!!
Iām testing to first dan this weekend!!!
Board breaking for rank test
- Thread starter auntlisa1103
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auntlisa1103
Orange Belt
Thank you Sir!! More than once Iāve heard my GM tell people to āflip the boardā, and I remember the basic logic of why, but I always forget the direction heās looking for lol
Honestly, I doubt it makes any real difference, but this does seem to be the most common way of stacking them. I think I know why, but the reasoning is false.
Bridges are arched because that means the weight (impact in a breaking scenario) pushing down on the bridge causes the ends of the bridge to want to move out, away from the weight/impact. Since the ends of the bridge are supported, the bridge is stronger.
Invert that arch, and the weight/impact causes the ends to move in, towards the weight/impact. Weakening the bridge.
Difference is that boards are not braced on the ends.
I think as long as the bows are all the same direction (because otherwise the stack is not going to be very stable) the actual breaking force will be the same.
Again, this is a great argument in favor of good re-breakable boards or concrete for breaking.
So I have this research habit.....
One of our kids is did his undergrad work in Mechanical Engineering. His Masters is in Control Systems. So will his PhD, when he finishes.
According to him, the direction of the curve will make a difference. The big question was, of course, "how much?".
I don't know your school, but if I saw a huge warp, I'd toss the board. But minor warps, where the deflection is 1/8" or less are commonly used. With that assumption, the difference between curve up and curve down on an un-braced board is roughly 1-2%.
I find it unlikely that a difference that small will affect your break. You will get a much bigger difference based on water content.
One of our kids is did his undergrad work in Mechanical Engineering. His Masters is in Control Systems. So will his PhD, when he finishes.
According to him, the direction of the curve will make a difference. The big question was, of course, "how much?".
I don't know your school, but if I saw a huge warp, I'd toss the board. But minor warps, where the deflection is 1/8" or less are commonly used. With that assumption, the difference between curve up and curve down on an un-braced board is roughly 1-2%.
I find it unlikely that a difference that small will affect your break. You will get a much bigger difference based on water content.
Earl Weiss
Senior Master
2 factors at work. 1. Boards / wood are stronger under compression than tension 2. Result is boards break from the back to the front. So, the top of the arch is already moved toward tension so keep it going in that direction.Beat of luck for your first Dan test!!! Remember to breathe, and ENJOY every moment of it
Ji Yuu
Yellow Belt
I try to use flat boards.Out of curiosity, what strike are you using? How many boards?
Most prefer flat. I don't know what it's like in your area, but in mine, if I run down to Loews and grab a bunch of boards to chop up, it's quite likely there will be some minor bowing. They're for breaking, and it's not really worth the time it would take to dig through in order to find all perfectly flat boards.
dvcochran
Grandmaster
If possible, badly bowed/crowned boards should be culled.
A major reason is simply for holding the board(s) (in the case of multiple board breaks). If a bow is held inward when stacked with another board (where the edges of the board do not touch the joining board) it is harder to hold and can move around during the strike.
There are a Lot of variables (species, moisture content, knots, etc...) but a pine board can compress/flex as much as .313". Using a maximum of 1/16th" as the allowable bow of a usable board, that is more than double the allowed bow. What does that mean? That the board will compress and flatten on the other board before any significant structural change takes place. There will always be exceptions.
If the board(s) are held by hand it matters more. If you have a clamp style board holder then most everything is factored out.
All that said, the short answer is hold the board so that the crown (center bow) is facing toward the person doing breaking.
Ji Yuu
Yellow Belt
What I do is get the flattest planks and cut them down. The bowed boards I use for single breaks. The flatter ones I use for heavier breaking. I have actually thought about using thicker wood (2" or 3" boards instead of 3 one inch boards).
auntlisa1103
Orange Belt
Thank you!! My biggest worry is actually stamina for the free sparring section, which has always been a thing for me. But I had Omicron (tested positive 1/13) right at the end of a two week sinus infection, so we werenāt sure for a bit if I would even test this time.Beat of luck for your first Dan test!!! Remember to breathe, and ENJOY every moment of it
auntlisa1103
Orange Belt
One board each for a hand and a foot. My techniques of choice are a palm strike (which we do vertically down over a board on cinder blocks), and a jump side (which we do with human holders).
auntlisa1103
Orange Belt
Not to mention how expensive all lumber, to say nothing of perfect lumber, has become.
auntlisa1103
Orange Belt
My GM told us last weekend at Black Belt Class:ENJOY every moment of it
You are GOING to make a mistake next week. Everyone does at some point. When Iām judging, I grade on what you do NEXT. How do you RESPOND when you make a mistake? Do you break down? Do you come back from it? Do you walk through it?
Remembering that helps. In my test for my current rank, we were supposed to do Taegeuk Pal through Oh, in that order, without stopping. Only I completely brain farted by the end of Pal that we were supposed to keep going. So Iām standing in a lunge punch, waiting for a Koman thatās never going to come, and suddenly I come out of my zone enough to realize everyone around me is still moving. Then for the LIFE of me I cannot remember what weāre supposed to do next. Stood there trying to think for a solid 30 seconds before I remembered Chil. Then I did the first combo on both sides in the wrong order (I did we su-snap-push block instead of push-snap-we su). After that I was fine, although rushed because I wanted to catch up pace-wise.
And I still passed!!! LOL
auntlisa1103
Orange Belt
I hear that. I feel like they have their reasons for doing all rebreakables until you test for Temp (probationary) Black and then all real wood from there.
There are certainly junk re-breakables, but good ones are just superior in every way to wood.
Earl Weiss
Senior Master
FWIW if you are still going to the store, buying boards and cutting them yourself to length for breaking see what it costs you and compare to ordering from Breaking Boards | Martial Arts School Breaking Boards | Karate & Taekwondo Boards
Earl Weiss
Senior Master
Good quality rebreakables fit holders for 1x2 buy might need a small shim. - not kid stuff Official ITF tournament rebreakable plastic boards
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