Thread: Advice for building a see-saw

Look I'm nervous because the board in your example seems to be covered with cloth or canvas.

do you have a plan or are you making the design and construction up as you go along?

If yu want to save weight, perhaps you need to consider fiberglass as used for diving boards

this is what I found on wikipedia
The teeterboard (or Korean plank) is an acrobatic apparatus that resembles a playground seesaw. The strongest teeterboards are made of oak (usually 9 feet in length). The board is divided in the middle by a fulcrum made of welded steel. At each end of the board is a square padded area, where a performer stands on an incline before being catapulted into the air.

Glue won't work, it'll delaminate it no time with the constant flex/stresses it'll sustain.

Agree with Ian if you want to save weight I'd be looking towards some kind of composite material rather than wood.

I'm not sure your background/skills/technical training on the matter but this is definitely something I'd won't be tackling without an engineering background or know of someone who'll sign off on the design.

Walk away from this one while you still own whatever you have, I see nothing but trouble if it goes pear shaped during use

I'm also not convinced that Vic ash is a suitable wood.

I think that the board should be constructed from a wood with good "springiness" like what is typically selected for tool handles. Spotted Gum comes to mind as a tool handle wood.

I found a reference to using European larch because of its "excellent elastic properties and springiness" but the youTube poster appears to be from the "look how easy it is" category of poster.

Originally Posted by rwbuild

Walk away from this one while you still own whatever you have, I see nothing but trouble if it goes pear shaped during use

excellent advice

Originally Posted by ian

excellent advice

Having seen the video link, I cannot agree enough with walking away from this.

That board gets a punishing, and any failure is going to be horrendous.

Thanks for advice so far fellas. Failure is definitely expected with the boards, for example cirque du soleil go through approximately 1 per week. We had intended simply to use the original design from the circus, which they were more than happy for us to do. We mainly wanted to at least look at other potential methods for building. Will definitely give the glue a miss now. Any other advice is appreciated though regarding the build.

$50,000,000 should cover you, most companies have that cover for around $10,000

Originally Posted by cuzzin_kevin

Thanks for advice so far fellas. Failure is definitely expected with the boards, for example cirque du soleil go through approximately 1 per week. We had intended simply to use the original design from the circus, which they were more than happy for us to do. We mainly wanted to at least look at other potential methods for building. Will definitely give the glue a miss now. Any other advice is appreciated though regarding the build.

there appears to be a range of skills involved in making a circus teeterboard, especially in the fulcrum part.

go and talk to the people who build the boards for cirque du soleil.
ask them "how much?" to make you say 5 boards.

then ask cirque du soleil -- "how do you determine that a board has "failed" and it's time it was replaced?"

come back and share the answers with us

Originally Posted by pommyphil

Wood turning ??

Yeah man, he wants decorative ends on the pivot!! hahahaha

Originally Posted by pommyphil

Wood turning ??

Has been moved as it is better to have this thread in General Woodwork sub-forum.

The suggestion of an analogy with diving boards is a good one. They are not wood.
Maybe some form of engineered fiberglas is useful with a good Modulus of Elasticity.
Even the lay of the cloth matters. Fiberglas failure sounds like ripping cloth and smells like money.

I don't know about Vic ash, but ash in general is a very elastic wood. If you buy one, take care to have a slap that is as knot-free as possible and to get one that has the widest brown core area. The white outer areas aren't as strong and elastic.

Wood is more elastic the more fibrous its cells are. Good wood species are for example ash, elm, birch or hickory (unfortunately I only know European wood species).

I wouldn't try to glue the board from layers, the glue surface is very large and you need a lot of pressure to get a neat glue joint. This pressure probably cannot be applied with screw clamps alone. Glued wood is usually more stable because the knot inclusions are interrupted.

Larch wood is rather brittle and completely unsuitable for your purposes. I've worked with it a lot.It is resinous and is often used outdoors.

Cheers,
Andy