Board breaking for rank test

[auntlisa1103]

Which way do you crown the board on the blocks for a hand strike? I always forget.

I’m testing to first dan this weekend!!!

 

[Dirty Dog]

Ideally, the board won't be warped. But if it is, put in with the bow going down.
One of many reasons I personally prefer breaking concrete pavers.

 

[auntlisa1103]

Thank you Sir!! More than once I’ve heard my GM tell people to “flip the board”, and I remember the basic logic of why, but I always forget the direction he’s looking for lol

 

[Dirty Dog]

Thank you Sir!! More than once I’ve heard my GM tell people to “flip the board”, and I remember the basic logic of why, but I always forget the direction he’s 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.

 

[Dirty Dog]

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.

 

[_Simon_]

Beat of luck for your first Dan test!!! Remember to breathe, and ENJOY every moment of it

 

[Earl Weiss]

Beat of luck for your first Dan test!!! Remember to breathe, and ENJOY every moment of it

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.

 

[Ji Yuu]

Which way do you crown the board on the blocks for a hand strike? I always forget.

I’m testing to first dan this weekend!!!

I try to use flat boards.Out of curiosity, what strike are you using? How many boards?

 

[Dirty Dog]

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]

Which way do you crown the board on the blocks for a hand strike? I always forget.

I’m testing to first dan this weekend!!!

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]

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.

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]

Beat of luck for your first Dan test!!! Remember to breathe, and ENJOY every moment of it

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 weren’t sure for a bit if I would even test this time.

 

[auntlisa1103]

I try to use flat boards.Out of curiosity, what strike are you using? How many boards?

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]

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.

Not to mention how expensive all lumber, to say nothing of perfect lumber, has become.

 

[auntlisa1103]

ENJOY every moment of it

My GM told us last weekend at Black Belt Class:

You are GOING to make a mistake next week. Everyone does at some point. When I’m 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 I’m standing in a lunge punch, waiting for a Koman that’s 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 we’re 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

 

[Dirty Dog]

Yet more reasons to use good re-breakable boards, or concrete for breaking.

 

[auntlisa1103]

Yet more reasons to use good re-breakable boards, or concrete for breaking.

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.

 

[Dirty Dog]

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]

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]

Good quality rebreakables fit holders for 1x2 buy might need a small shim. - not kid stuff Official ITF tournament rebreakable plastic boards