Choosing your hole sizes

You can choose the size of the holes in the whistle, and see the effect immediately in the whistle diagram.  Sometimes you will choose sizes that do not give a valid answer.  You will see that some holes are flagged with the word 'error', instead of a position, and the holes are not drawn on the whistle.  This is because two holes have become too close, or even reversed.  Look for the last hole with a valid position,  and start increasing its size.  At some point the following hole appear with a valid position.  You may have to adjust several holes to get them all on the whistle!

For each hole Whistle Calculator calculates the 'cut off frequency'.  This is the highest frequency that can issue from  the hole, and for a whistle you need this to be more than twice the base frequency of the hole, because you want to be able to overblow to the second octave.  There is a graph of 'relative cut off' in the lower window.  Relative cut off is the cut off frequency divided by the hole frequency, and so you should be looking for a value of two or greater at each hole. Choosing hole sizes is an art, but one thing you definitely want is the relative cut off to be above two.  Some people have suggested that you want the relative cut off values for each hole to be similar, others disagree.

Drill Sets

I have added the ability to specify the drill bit sizes, to load and to save the drill bit sets so created.  This feature uses dialogues, and so will only be seen in the stand-alone version (not the applet version above).

You can specify the size for each hole, and even offset the holes from the centre line.  The offset from the centre line does not affect the whistle calculations, but adds to the realism of the whistle picture.