"HBflutomat has been spot on for length" I'd say was rather fortunate for you! I would not like to rely on the calculated full length when creating a one-piece prototype whistle , as even small changes in the whistle's window dimensions will seriously flatten or sharpen the overall tuning.wormil wrote:I've built 4 whistles, only one turned out well enough to play (my inexperience, no fault of the calculators, one (4th) was an experiment in tiny whistles), but HBflutomat has been spot on for length. On the good one (my 3rd), the hole size/spacing was very close. At first the holes were a little undersized but after a day in the house, I had to drill them out to full size because the whistle had gone flat. So you might want to give it a day before going for final size. Now if I can get the head end in better shape I'll have some good whistles.
If you are finding that your actual holes need to be a bit larger throughout than the calculator says, it is most likely that the (bottom) end-correction factor in the calculator needs adjusting. HB Flutomat uses by default 0.56 as a factor (it assumes the vibrating air column is 0.56 * bore longer than the tube at the bottom end). I am using 0.5 * bore now, which has the result that all hole locations are moved up a little, thus producing slightly sharper notes (and therefore you may not need to widen the holes).
The bottom end-correction factor in the calculator has an impact on all hole locations, since they are measured from the bottom. So getting it right is useful.
The top or window or embouchure end-correction is important for the overall length, or the distance of the window from the bottom end. Getting this calculator function right would be useful for one-piece whistles, but very hard/impossible to achieve, so I use the calculated length from window to bottom end only as a rough guide. For tunable whistles it does not matter anyway much, since you can compensate calculator errors by adjusting the length in the tuning slide.
Or have your whistle tube cut a bit longer, then make the head to your satisfaction, till it sounds just right (and don't widen/enlarge the window later!), and then cut the bottom end to tune the base note, before any other holes. In theory you introduce a slight error with this method, since the effect of the closed tone holes is not present at this stage. But this effect is very small, and if the tube has fairly thin walls it can safely be neglected (My calculator says on a high D whistle with 13mm bore and 3mm thick walls the distance from window to bottom end should be 1mm shorter, with 1mm walls only 0.3mm shorter than a tube without holes).