We spend a lot of time discussing various low-Ds and their respective hole arrangements. High time we consolidated the info methinks.
Makers, if you see an error kindly PM the poster that measured amiss so that the post can be edited. Makers are also encouraged to post their numbers. 
Please don’t respond to the posts and clutter up the thread. Just post your whistles measurements in the following format:
1 shall be the top hole, 6 the bottom. Between the hole numbers shall be the distance between the holes from center to center. I’ll start with my personal Low-D.
Reyburn Offset Wide Bore (Hole sizes and spacings are the same for the inline model):
1. 10 mm
43 mm
2. 11 mm
40 mm
3. 10 mm (off-set)
49 mm
4. 8 mm
26 mm
5. 11 mm
50mm
6. 10 mm (offset)
Fipple to #1 center 274 mm
Fipple to #4 center 443 mm
Doc
Hi
Don’t wamt to interfere with your worthy cause here, but measurements from the lip to each hole, or at least to the top hole so we can do our own calculations for the rest would be useful not only for those who need to consider arm length, but for those who like to mess around building their own. And in that case, we do care about the distance between the hands too. Also, I find that in information that deals with whistlebuilding, the hole positions are always given as a distance from the lip.
Sorry for cluttering up your thread.
Happy Whistleblowing
Regards,
Owen Morgan
Yacht Magic
Anchored in the lagoon, St Maarten
My new blog.
Click here for my latest reported position. (Use the satellite view.)
HOWARD LOW D
TUBE DIAM = 1 inch
TOTAL LENGTH = 21.4 inches
FIPPLE TOP to TOP of FIRST HOLE = 10 inches
FIPPLE TOP to CENTER of FIRST HOLE = 10.2 inches
FIPPLE TOP to BOTTOM of BOTTOM HOLE = 18.2 inches
FINGER SPAN required is 3.2 inches for top hand and 3.3 in. for bottom hand.*
1st hole diam = 0.4 inches
Space = 0.9 inches
2nd hole diam = 0.45 inches
Space = 1.1 inches
3rd hole diam = 0.4 inches
Space = 1.65 inches
4th hole diam = 0.4 inches
Space = 0.65 inches
5th hole diam = 0.45 inches
Space = 1.45 inches
6th hole diam = 0.4 inches
Space from bottom of hole to bottom of tube = 3.2 inches
*NOTE - the finger span is for index, middle and ring fingers, and must include pads in a straight line so that the holes are fully covered. Be aware that, although you may have fine stretch for the span in one position, it may not work as well when you have your arm stretched out to reach the distance on a low whistle. (I use the “Piper’s grip”, which utilizes the second section of the fingers, behind the first joint from the tip, rather than the tip pads.)
I’ll put that in metric as well as soon as I have time to do the conversions.
Hi
My home made Low D LTW:
1. 9 mm - 248 mm from the lip of the fipple.
36 mm
2. 10.5 mm (slightly oval) - 283 mm from lip.
41 mm
3. 10 mm (off-set, slightly oval) - 324 from lip
(We obviously don’t care what the distance between the hands is )
I do: 47mm
4. 8.5 mm - 371 from lip
36 mm
5. 12 mm (average, the hole is oval) - 407 from lip
40mm
6. 10 mm (offset) - 447 from lip
The whistle is tunable, so I will make a new body where I’ll move hole 5 and 6 up a bit to make nr. 5 a more manageable size and 6 an easier reach. I don’t want to move nr 6 up too much as that will make it smaller and the whistle will be quieter on the E and possibly also the F.
Hope I got all the measurements to add up…
Happy Whistleblowing
Regards,
Owen Morgan
Yacht Magic
Anchored in the lagoon, St Maarten
My new blog.
Click here for my latest reported position. (Use the satellite view.)
Just thought I’d add that I list the dimensions for all the low whistles that I review on the pipersgrip website:
I just thought it would be easier to post this link rather than relisting the measurements every time I do a new review (don’t I do enough typing?! 
), hope this isn’t considered “clutter”!
Thanks! 
Kevin