Compound Tetrahedra

How ever did you figure out the cuts on this? I am very impressed. It is a lot of fun and quite attractive. I would not mind having one of these for the top of my Christmas tree.

-- Kay - Just a girl who loves wood.

That is amazing, thank you for sharing, and I am glad you took the shadow picture, that is really nice.

-- "Anyone who has never made a mistake has never tried anything new." - Albert Einstein

Thanks Kay. Its just a little math from those geometry/trig days! I used the law of cosines…I know its has probably been a while!
It involves taking a slice of a single tetrahedral, and giving a length to each side (say 1, which in a 30-60-90 makes the other side the square root of 3 over 2.

Yada Yada Yada…Long story short… the angle between the faces is 70.5 degrees. So if you cut the rods with a (70.5)(54.75)(54.75) and you miter with 60 degree angles.

All the rods should look like this before glue up.

-- -Joshuah

Murdock- Thank you, I found that it was hard to see the design by just looking at the wood.

-- -Joshuah

I like it alot!!! And wow the law of cosines seems like ages ago!!!! Good Job!

-- Sasquatcher

I agree with Murdock… and sasquatcher!!!

So how did you do the finishing on a project like this! Seems very very tedious!!

-- NewWoodie

Thanks all!! I actually did all of the sanding and most of the finishing before assembling. After assembly I think I put 3 more coats knocking it back with 300 grit in between.

-- -Joshuah

Well done.

-- Live to Learn

Very nice! A skeletal version of a stellated icosahedron!

Ref: http://mathworld.wolfram.com/IcosahedronStellations.html #17

I take it you built the tetrahedrons, intertwining the pieces as you went?

Very intuitive AtomJack. I hadn’t seen that link before, maybe I’ll have to step up my game and make a real complex one.
And you were spot on, I built the original tetrahedral, then would build one-by-one, locking them together as I went.

-- -Joshuah

Great project.

Man I hate math…........

-- mike...............

Looks great!

-- Dreaming patterns

One of the most intriguing wood projects I’ve seen. Fascinating.

-- Art | Bradenton, Florida

That looks like the way my picture frames turn out that aren’t supposed to look like that…

-- Randy "You are judged as much by the questions you ask as the answers you give..."

That is really cool!

AtomJack, I like to use math to get me where I want to go but those shapes blow me away!! As do the formulas!!.............Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!!