Has anyone made a whistle with a square cross-section? I know it sounds a silly request, and maybe it’s a bad idea, but it’s easier for me to get aluminium with a square cross-section than aluminium tube.
Have you considered a used ski pole? I got a few from a resale shop , but ended up throwing them away when cleaning garage. NA flutes are easier to make than whistles IMHO.
Sure no snow here in Pasadena, but if you look at resale shope , you may find some, cheap.
And they are nice & conical, who knows what you might come up with
The Whistling Archer
formerly Houston Steve,{terrible name" LOL
Mike, however will you make the square holes? 
Now there’s a challenge! Actually, I have access to a water jet cutter, so square holes would be possible. It’s the fipple construction that scares me.
round to square adapter & tuning slide?
Overtons seem to manage it.
http://www.celt.com.au/Images/overton.jpg
Flanna makes whistles with squareish holes.
(Or at least they did, they don’t have pics
up anymore.)
http://www.flanna.com/flanna/component/content/article/15-research/15-historical-designs
I have not tried square aluminium tubing, but I would think it should work okay. Some organ pipes are made as square wooden boxes. I am curious if it has an effect on the sound, let us know!
Yeah. I meant the whole making the fipple / mouthpiece end really. Any fool can drill holes in a length of pipe (as I intend to prove) but making a mouthpiece (especially in metal) is tricky. Actually plan A is to get hold of some aluminium tube the same diameter as my polymer Dixon low D and try swapping the head across.
It’s been done, successfully, in The Land of The Fipple Flute That Shall Not Be Named. The link below is one of many you’ll get if you google “square recorder.” The square ones seem to be mostly in the larger sizes. The holes are round, I think.
http://www.alte-musik.info/en/instruments/galleryinstruments.html
Some time ago there was a whistle with square holes available. I’m sure it is in the C&F archives someplace. However I don’t remember anyone doing a review on one. There are also available flutes with square holes. The square hole whistle kinda drifted away with the ring flute. http://www.ringflute.com/hear.htm
Square holes can be made with a metal punch or drilling a round hole then squaring with a file. I have some 1/2’’ square tubing but have not done anything with it yet. I will most likely use round holes 
being to lazy 
to figure 
the calculations for the position of square holes.
This topic comes up every now and then. And as Walrii has, the Peatzold r#@^$#er design is always brought up as a good example. That’s the first thing I think of as well. Others here have made square section whistles to try out the concept. Here’s one thread where it was discussed.
https://forums.chiffandfipple.com/t/why-cylindrical/1599/1
One thing I recall is an advantage of the square section whistle design. It doesn’t roll off the table.
Here’s the thread where a chiffer made one such whistle.
https://forums.chiffandfipple.com/t/see-the-barely-playable-squistle-i-made/11172/1
Feadoggie
surley it wil produce a square wave?
o’ course…makes the ornaments crisper, dunnit!
I have a tapered whistle in d, with a square cross section, which was given to me 30+ years ago by a man who said it was a prototype of something he was going to produce. Never saw any more of them.
There was a whistle maker named Goodfellow, Canadian I believe, who made square sectioned, tapered whistles that were rolled like a Clarke. It was held together with epoxy. The fipple plug was of red plastic. I’ve got one and it works pretty good.
Regards,
Paul N.
Nah, the fipple is easy. Square tuning slide?, now that’s hard. When I make NAF’s and wood whistles, it starts out as square.
For the fipple, make a square wood block the fits nice and snug and then mill out a air duct path about 0.0425" deep that would be angled so that the the floor angle intersects with the lip which is 0.225" from the edge of the block. A minor 45 deg chamfer on the edge and break the sharpness of the ceiling slightly. It makes a nice loud instrument.
I think the fipple construction is the hard part though getting the holes right is perhaps not as easy as it first seems.
edit - I just reread your post and yes a square slide would be hard!
Bad fipple and the whistle hardly works, bad holes - well they can often be made acceptable, little bigger, or add a little wax or whatever and the whistle will play regardless. Square slide? - who needs to tune?!?
Newbie constructors should thank Daniel for giving them a starting point. And more seasoned whistle builders can probably learn a little too. So thank you Daniel for posting some numbers.
Daniel: for what whistle (bell note) are your measurements?
Bill