People have complained about the Mello D being too sharp. It seems to me that one could pull the head out until the bell note was tuned, and then enlarge the other holes to bring them in tune.
I would think this would work, I use a tile cutting bit clamped in Vise Grips to make holes when I build whistles myself. The tile bit is shaped like a countersink bit and is cheaper an less time-consuming to use than enlarging the holes using individual drill bits or a stepped drill bit.The holes don’t always end up perfectly round, but it beats a out of tune whistle.
Take care, Johnz
Or the manufacturer could make them better in tune in the first place…
This seems like a lot of trouble to go to, finishing the manufacturer’s job for them.
Sorry, I’n not usually this harsh, but why should we all have to buy poorly made whistles & then fight to get them in tune?
Actually I have Mellow D, and I’m not bothered by the sharr bellnote, but probably because I rarely play it.
Johnz,correcting the bell note first will mean less work on the tone holes.Doing the correction as you suggest will make the tone holes gigantic and the bell note problem will still exist as larger tone holes necessitate a slightly longer barrel.
Martin,I agree the manufacturer ought to get it right in production but the Mellow D offers the ultimate challenge for extreme whistle tweakers like myself…I love them just as they are. 
Mike
I’m a Mellow D lover too. It’s a whistle with an Irish accent. I recenly tweaked it with a piece of thin plastic stuck to the labium. The plastic strip made it sweeter and purer, but I like it either way.
I’m with Martin on this one. If I want to spend time working on whistles, I’ll learn how to make my own. Mass production techniques being what they are these days, it’s not unreasonable to expect that an instrument as basic as the tinwhistle be playable direct from the manufacturer…especially when there are so many competing (and playable) whistles out there in the same general price range. I sure wouldn’t recommend anyone purchase a Mellow D, unless they are specifically looking for a whistle to tinker with or hybridize.
If a person happens to own a Mellow D anyway and has the time and the inclination to try to make it into a decent whistle, that’s fine. I’d rather spend my whistle time playing, but different strokes for different folks. In fact, I’ll happily give my Mellow D free of charge to anyone who wants to tinker with it…seriously. Anyone who wants it, drop me a line.
Redwolf
Redwolf,Mellow D,s are extremely playable and,as far as I know,one of the only wider bored cheapo soprano D,s in production.Out-of-tuneness is a feature most inexpensive whistles share..unfortuneately,great tone is not.Try sticking a small ball of blue tack inside the end of the barrel to lower the bell note before you give it away. Mike
Speaking of Waltons, I was in a music store today and saw an “Irish Rainbow Whistle” in a little plastic box with yellow shamrocks on the plastic.
On closer inspection, it was just a Waltons LBW…no rainbows to be seen anywhere. Just the normal black aluminium whistle with yellow sticker proclaiming it is the LBW. Where the heck did they get “rainbow”??