So, I produced this quick paper accordion model to go with the paper bellows but it does nothing beyond looking pretty.
I really wanted it to make a sound. Proper accordion sounds are impractical in a project this size but a bit of discordant whistling would keep me happy.
To the drawing board!
I've learnt through my various past experiments that a whistling pipe needs a tapering blow hole blowing air over a slot. I fitted some baffles inside the hex box (black lines above) to direct the air and fitted a tapered blow hole lined up with a suitable slot. The result: perfect whistling! 1046hz according to the app on my phone. Roughly a 'c' two octaves above middle 'c'
The downside being the big sticky-out-bit on the side of the box. I wondered if I could fit the tapering tube inside the body of the hexagon.
And so we have this. Air, to be provided by bellows, blows though the hole in the side of the box through the tapering tube and across the underside of the slot at the top of the picture above.
Once assembled and with the glue dry the finished box sounds a nice clear whistle. I'll make another with a different note by moving the baffles inside to change the volume of the resonant cavity and fit that at the other end of the bellows.
With the bellows in place a quick test shows that everything is working nicely so far...woot woot!
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A set of paper bellows/springs to download and make. Members can download the template at the link, thanks for signing up! There are three designs in the template file, pentagon, hexagon and nonagon (9 sides) Check out the previous blog post if you would like to design you own with a different number of sides.
Print out the pages onto standard printer paper, not card. Score along all the dotted and dashed lines then cut out the page along the surrounding line. You may have to set your printer to "Scale to Fit" to ensure that the whole template is printed out.
The three pages look like this.
Pre-crease all the dotted and dashed lines before you glue the parts together. These instructions are illustrated with the six sides spring but apply equally to the other two.
Glue along the back of the edge opposite the grey area.
Roll the tube round and glue down exactly on the edge of the greay area.
Okay - now this is fiddly and a little tricky. Take your time.
Starting one row of parallelograms from the top. Pick a parallelogram. Fold the centre diagonal as a valley fold and the four surrounding edges as hill folds.
Once done move onto the next parallelogram on the same level and repeat the process.
Work your way round to complete the row.
Repeat the process with the next row down.
Work your way right down to the end.
Complete the spring/bellows by folding in the ends noting that the hill and valley folds are swapped in the ends compared to the main body.
...now if I can just fit some sort of sound generator, perhaps a whistle or two, into this mini squeeze-box...
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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.
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A crafty creation for you to download, print out and make. Print out all the parts on your own printer then make this fascinating mechanism.
Pump the paper bellows on this intriguing model and the rotor spins. Cardboard engineering in action!
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An amazing project for you to download, print out and make.
The train whistle model uses a pair of tuned pipes to make the sound of a train whistling. Print the parts onto card and the bellows onto paper. Follow the illustrated instructions to make your own working paper whistle!
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