So I found these instructions:
http://www.ehhs.cmich.edu/~dhavlena/low-d.htm
and as I had a piece of 1 inch diameter aluminium alloy tubing I decided to give it a go.
Yesterday:
Cut the tube to approximate length plus 2 cm to give me some leeway for error.
Cut the window and filed out the burrs.
To do this I put masking tape on the tube, marked it out in pencil, drilled the short edges with a small drill bit and used a fine junior hacksaw blade to cut the top and bottom, then I filed them out using a needle file.
Made the fipple plug.
To do this I cut a bit off the end of the handle of an old garden brush which was a good fit in the tube already.
Put some sandpaper on my workbench and rubbed it backwards and forwards till I had taken enough off it to get an airway 17mm wide (to match the window)
Made the ramp.
I used a hammer and the round end of a radiator plug to “panel beat” the depressed area over a large number of strikes with the hammer.
I tried to align the edge of the lip so it was straight but this is not easy with aluminium, I can see now why so many makers mill out the lips in aluminium whistles.
Then I filed the edge slightly sharper to give me a start at being able to make a sound.
Shaped the wind way.
I put the fipple plug in the tube, taped the tube to my bench with gaffer tape and used a block of wood and a hammer to shape the top of the airway slightly flatter. Again a lot of short sharp strikes while moving over the area to prevent the tube being damaged. The wood protects it also.
Testing.
Took whistle indoors and left it to reach room temperature then blew some air through it to warm it up.
Taped the fipple block in place and was surprised to make a sound, this was a bottom C#
Glue the fipple block.
I used impact adhesive because thats what I had.
I also used it to fill the gaps between the wood and the tube now that it had been slightly distorted.
Total time to do all of the above was about one hour plus coffee break.
I had to leave it for the glue to set overnight.
Tools used so far:
Hammer
Wood block
Mitre saw (to get the fipple block ends straight, although you could use any saw).
Sandpaper
Junior hacksaw with a fine blade
electric drill and drill bits
needle files
chromatic tuner (could use a piano or other tuning aid)
Today:
Checked for seal round the fipple block and all was OK
Warmed it up and tested the tuning, still just under C#.
Spent one hour (yes one hour) trying to get the manufacturers label off the tube!
It was laminated on with plastic and I ended up using solvent.
Tuning of root note D
Cut the tube with hacksaw about 6mm at a time till I was showing a flat D.
Then very carefully took small amounts off (filing might be easier) until I hit it correctly.
Making of holes
I put masking tape right down the centre of the tube and marked the centre line in pencil.
Then calculated the positions of the holes using the formula in the article.
I decided to offset some of the holes as I have short fingers and I did this by looking at pictures of commercial whistles.
Drilled the holes with a small drill bit and removed the masking tape.
Tuning
Started on the furthest away hole, enlarging it with successive drill bits until it got higher in pitch and nearly in tune.
Then used tapered reamer to adjust it more precisely.
Could use a rat tail file for this or just successively larger drill bits.
Tools used today in addition to yesterday:
Tapered reamers (not necessary, could use a file or drill bits)
Time spent in total so far, about two hours in total plus the time it took to get that label off.
So far I have bottom two notes playing in tune.
Next task will be to tune the other notes and then make sure the lip adjustment is right for a good tone on every note.
Will post about this later.