Hi, this is my first posting on this site and what my question is what the ideal note values should be for a brass whistle in d tuning intended for playing Irish music? I remember reading somewhere something about the bottom d and b being quite flat with the f# being slightly flat and something about the second octave tuning being different too. Also how accurate is considered “close enough”? And finally is there a way to solve octave mismatches by adjusting hole sizes and filing the hole shapes? The brass stock I’m using is thicker than what might be considered typical but all in all sounds good to me. Thanks for reading and I do appreciate any comments.
I suspect there are those who would tell you to tune the whistle to just or 1/4 comma mean tone tuning. I’d suggest getting a decent tuner and tuning the thing to a nice equal tempered scale by using the tuner. There are tricks about undercutting the holes if the walls of the instrument are thick enough and also tricks about how to get the two octaves best in tune, but all I know about them is that they exist. Someone else will have tp speak to the details.
Go for it.
There are tons of post on this site about intonation - do we tune just or even temperament?
Search them - you are in friendly company!
In a thin-walled whislte, I will tell you - the hole-size is critical fro tuning in the first and second registers!
On a D whistle - it matters not much, our fingers can adapt to the prime distances,k BUT it is a differenent metter in lower keys a the physics must comrimise with the reality of a hand.
A word to the wise: the second register is like crossing the speed-of-sound barrier 
Go look - google “chimney”. I found this out by experiment ( I am patient and have nothing to lose) - I don’t give a toss who found it before me - I live in the “intellectual-property” age as do you all - and look what the “industrial revolution” did to us? [[[Delete the “r” and get to where you are]]].