# How Do I Build a Pyramid Shaped Urn?



## Boxguy (Mar 11, 2012)

Edited: This is the finished result and posting.










I know this is going to sound like one of those word problems from my high school algebra text book, but it boils down to this: I need to build a pyramid-shaped urn.

My patron raises Saluki dogs and has them cremated when they die. She wants to put the ashes into an urn shaped like the Great Pyramid of Egypt. She doesn't want to mix the ashes together and wants to put ashes of 4 dogs in each pyramid. The Great Pyramid has 4 sides of 440 cubits each and is 280 cubits tall in the center. I won't drag you through all the math of proportions and volume.

I need a pyramid that is 18 inches on each of four sides and 11 1/2 inches tall in the center. At that size, the sides will need to be made of 1/2 inch veneered plywood.

I thought I'd start the frame with two crossing triangles 25.45 long at the base and 11 1/2 tall in the center. That would give me the 4 compartments and the support I need for the edges of the 4 sides.

Have any of you built something like this? Do you have any hints?


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## Tootles (Jul 21, 2011)

I have never made anything like this, but I think your idea is good.

The best suggestion that I have is to draw it up in Sketchup or similar and then produce dimensioned drawings (including angles) from there. It sounded like an intriguing little challenge so I have just had a go at drawing it, and it is not too hard. Of course, dimensioning could be a different matter!


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## GrandpaLen (Mar 6, 2012)

Big Al,

After a severe strain of the Grey Matter, reaching back 46 years to Geometery Class, I decided to "let my fingers do the walking" so to speak.

I think you will find the Geometric Formula you are looking for at this site;

http://www.bing.com/images/search?q=Geometery+of+a+pyramid&view=detail&id=EDF28566720DA648C44695388A3EAC1489FC5811&first=0&qpvt=Geometery+of+a+pyramid&FORM=IDFRIR

Have fun.


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## Boxguy (Mar 11, 2012)

Tootles,

If you draw this up I would love to see the results.


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## Boxguy (Mar 11, 2012)

Grandpa Len,

Thanks for the web site. I'll use it in the plans. Who knew Mr. Smith's geometry class would still be part of my life 50 years later? Keep boxing.


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## Kernal (Mar 1, 2012)

I assume that, because you're using veneered plywood, you intend to use mitre joints where the faces of the pyramid meet. Note that, with a shape like this, the correct miter'd angle is not 45 degrees, but some angle greater.

In case this hasn't already occurred to you, I can try and calculate the correct angle.

Cheers,
Kernal


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## chrisstef (Mar 3, 2010)

boxguy … LJ Jim Jakosh does a great blog makng a solid obelisk. Hopefully it can help ya out in osme way. (I edited this post b/c i jumped to conclusions).

http://lumberjocks.com/Slovenian/blog/26922


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## Tootles (Jul 21, 2011)

There you go, Jonathan beat me to it. But I drew it slightly differently, as you can see below, so here is my version.










The way I drew it, the edges of the two crossing triangles are visilbe from the outside, whereas they are hidden as Jonathan drew it. It just shows that there is more than one way to solve a problem.


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