GBP

## Designing Bellows

Friend of the website Edgar pointed out this fun design on the Instructables website. The download with the article was the template of a pentagonal spring. In the pictures, other designs of spring were shown but no templates were provided. Below, I have presented the techniques for creating your own spring with any number of sides.

The template for the five sided spring looks like this. The spring is divided into five vertical sections, the sixth, grey, area is where the sides overlap to make a tube.

Each unit of the spring is made from a parallelogram divided diagonally with a crease line.
The sides of the parallelogram are all the same length. In this case, 38mm.

To calculate the angle of skew of the parallelogram it is simply a matter for dividing 360° by the number of spring side – in this case 5 giving an angle of 72°

360/6 = 60° for the six sided spring.

and for the nine sided spring. 360/9 = 40°

I'll be uploading templates and instructions shortly for those of you who want to try your own.