There are so many variables in pipe design! Width of the hole, height of the hole, x and y dimensions of the air slot, position of the air slot. That's six variable right there and that's not even leaving the throat of the pipe!

To allow me to experiment a bit with some of these variable I've stacked up cut cards but held them together with with bulldog clips for easy disassembly. Neat eh?!

Here is the sound from a 12 x 3mm opening.

A bit breathy perhaps but with some promise. 

Looking at the parts from various angles it became apparent that the edge the air flows over, vital in the sound production, was slightly bowed. Make it narrower, I thought, then there will be less room for bowing.

I reduced the width by a half and tried various slot heights  2mm: (Fading out slightly if I blow too hard)

3mm: (Sounds good!)

...and 4mm (sounding a bit hissy)

...before settling on 3mm as the optimum size.

I then experimented with the height of the air slot by adding extra layers of card in strategic places resulting in what I think you'll agree is the cleanest sound yet.

Having optimised some variable I carefully stacked up the parts, gluing each layer to the next.

With the glue dry and the bull dog clips removed I ended up with this.

A completely silent pipe! Arghh! Pipes are so frustrating! I'm pretty sure that it comes down to tolerances. I'm going to have to think of a way of having errors that cancel each other rather than adding up. Bleugh. That's it for today though. #1 Son and I are heading off to set up lights and sound at the local am-drams. It'll give me space to think...

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Bliss Kolb released this YouTube video of a fabulous singing bird automata. As a fan of sound making automata I was intrigued by the high pitch whistling. Keen to try and produce the same sound in card I scaled down the twitter box pipes but found that tiny errors in construction were magnified in the small model and the pipe didn't sound. How about a different approach? A laminated box?

I printed out twenty or so identical rectangles and started cutting.

All the parts stack up to make a whistle outline.

Complete! Blow through the hole in the bottom for a surprisingly clear and startlingly high pitched tone.

I didn't actually glue the parts together, just stacked 'em up. I'll try gluing them now so that they have overnight to dry and report back in the morning.

(btw I love my 50mm f/1.4 lens :-)

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S/stan reminded me about the Curious Cuckoo Whistle which I had originally posted on Flying Pig website some time ago. Flying Pig is now entirely dedicated to printed material so I thought that I'd dust off the file and add it to robives.com.

The curious cuckoo whistle is a real novelty in paper engineering. A simple box shaped whistle that produces two distinct notes. The pitch is changed simply by touching the sides of the box. 

The file is available for everyone to download for free. Just click on the link. Print the single page out onto thin card (230 micron, 230 gsm) score along the dotted lines then carefully cut out the parts. Accuracy is important on this project, if the parts are mis-aligned or there are holes in the box it probably won't work.

Fold up and glue together the box... 

...and glue the tab down

Glue the sides of the box over the top of the box making sure that the parts are aligned.

Glue the saddle into place lining it up with the edge and the base of the box 

Let the glue dry completely.

To use the whistle hold it top and bottom between thumb and forefinger of one hand. Touch the burst pattern on the side with finger and thumb from the other hand to change the pitch.

I'm not sure how it works. Anyone got any ideas?

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