# Creating a 3D Pentagram: Find Equation for Sheetmetal

• lookingdown
In summary, the conversation discusses the use of an equation to create different sized 2-D pentagrams out of sheetmetal. The speaker also mentions the existence of 3-D pentagrams and provides a link for reference. They explain their problem with changing the size and angles of the pentagrams and request further elaboration. They also mention the use of diamond shapes and bending them in a metal break to create the angles needed for the pentagrams. The speaker provides diagrams and asks for clarification on the placement of the center and points. They suggest a trial method for creating the pentagrams.
lookingdown
Im looking to find some type of equation that i can plug numbers into for making a number of different sized 2-D pentagrams out of sheetmetal?

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lookingdown said:
my mistake.. I am running into the problem that if i change the size, all my angles change.
I think you're going to need to elaborate.

DaveC426913 said:
I think you're going to need to elaborate.

i am making 2 dimensional pentagrams.. i am running into the problem that if I make one to a certain size I can't just enlarge the pieces to make one bigger.. ??

see I am basically cutting out diamond shapes and breaking them in a metal break to put an angle on the diamonds running the length of them,, but where they all connect at they have to be a certain angle and I am not sure how to upsize or downsize measurements to make this work out

Can you supply a diagram or a photo?

These diamonds, are you basically making 5 of them and joining them into a star pattern? The central angle would be 360/5 = 72 degrees. It is not the same as the angle at the outer point, which will be different if you want them to be true pentagrams, as opposed to simple stars.

See attached samples of different five-sided shapes.

I suspect you are trying to construct #1. But if you use true diamond shapes (opposite angles are equal), you will end up with #2.

#### Attachments

• PF20091217pentagrams.gif
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they are not flat they are raised in the middle.. see I am putting a bend right down the middle of the center of the diamond so it sticks up in the middle..

lookingdown said:
they are not flat they are raised in the middle.. see I am putting a bend right down the middle of the center of the diamond so it sticks up in the middle..
Ah. But otherwise, does it look like #1 in my diagram?

How much is it suppsoed to bend up?

yes it does look like that diagram it doesn't matterjust nothing with too much of a pitch

lookingdown said:
yes it does look like that diagram it doesn't matterjust nothing with too much of a pitch

Is the centre raised with the points set back? Or are the centre and points in the same plane? i.e. if you lie it flat on the table, will the centre touch the table?

[ EDIT: Nevermind, the centre and points can't all touch ]

If you want to simply do a rough trial, then try this:

Take one of the diamonds I diagrammed.
On paper, scale it up to the size you want.

This should get you a diamond whose inner angle is a now little more than 72 degrees. You will need to crimp it down the middle to make it 72 degrees, at which point 5 of them will complete a circle.

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center raised out

1.

## What is the purpose of creating a 3D pentagram using sheetmetal?

The purpose of creating a 3D pentagram using sheetmetal is to have a physical representation of a mathematical concept. It can also be used in the design and construction of various structures such as buildings, sculptures, and decorative objects.

2.

## What materials and tools are needed for creating a 3D pentagram with sheetmetal?

You will need a sheetmetal material, a ruler or measuring tape, a protractor, a compass, a pencil, and a cutting tool such as tin snips. Optional tools that may be used include a hammer, pliers, and sandpaper for smoothing out rough edges.

3.

## What is the process for creating a 3D pentagram with sheetmetal?

The process involves measuring and marking the sheetmetal according to the desired dimensions and angles, cutting out the necessary pieces, and then bending and connecting them together to form the 3D pentagram shape. It is important to carefully follow the steps and make precise measurements to ensure the final product is accurate.

4.

## What is the equation for creating a 3D pentagram using sheetmetal?

The equation for creating a 3D pentagram using sheetmetal involves calculating the dimensions and angles of each piece of sheetmetal based on the desired size and shape of the pentagram. It may be helpful to use trigonometric functions and geometric formulas to determine these measurements.

5.

## Are there any safety precautions to keep in mind when working with sheetmetal for this project?

Yes, it is important to wear protective gear such as gloves and eye protection while handling sheetmetal. It is also recommended to work in a well-ventilated area and use caution when using cutting tools to avoid injury. Additionally, make sure to properly dispose of any scrap metal and clean up any sharp edges before handling the final product.

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