**Here's a maths challenge for you,**

**How do you make a regular tetrahedron from square stock?**

**The crux of the problem is the compound mitre joint that must be cut.**

**There is a 54 and 30 degree angle in there somewhere from memory.**

**I suppose I have not figured out the jig - I only have a band saw and circular saw, neither very good, made many jigs for this, feel silly really...**

**Also you can construct an equilateral triangle from square stock....**

**Just by using a 45 degree mitre saw...**

**I was happy when I figured that one out!**

__Quick Update__**Just thought I would add that this is my 222nd post.**

**The number 2 is very important to me.**

**Might be a while till I get to 2222....**

Berin,

ReplyDeleteTo make a regular tetrahedron from square stock, I'd lay it out and cut it by hand.

Doesn't a equilateral triangle have three 60-degree corners?

Chris

Hi Chris,

ReplyDeleteBy this I presume you mean cut a 30 degree mitre on each piece?

Unfortunately it does not work...

The angle between 2 faces is 70.5288, so you would think half of this would work...

Unfortunately it does not...

I should not let my GCSE students make such complicated stuff. We solved it with making it from regular triangles, but I never got the jig to work accurately for square stock production. I will post some pics of the jigs at some point. I just don't have time to solve all this properly as I am so busy.

All the best!

Berin.

Berin,

ReplyDeleteI am thinking layout and you are thinking about cutting it with revealed reference surfaces. I think we're both right.

Chris

PS: If you like geometric shapes and mitres and other complications, you might like this table base I designed and intend to make.