I recently got a bamboo Billy Miller flute in F, which has been a lot of fun. I’m thinking of adding a D flute to the arsenal now, but have a couple of questions/concerns. The “E” hole on the Miller is quite large, and I’m still having some problems covering it. I compared it to my low D Tipple, and it’s bigger than it, despite being a higher key. So my concern is whether the hole would be even bigger on a Miller D. Does anyone happen to have either Millers in F and D to compare the sizes, or a Miller D and a Tipple D to compare sizes?
There is a difference in how the tone holes are cut in a flute. Many makers of bamboo flutes use a hot tapered poker to make the holes. Using this method you locate a place on the flute body where you think the 6th tone hole will be, and you enlarge the hole until you have the tone pitch that you are looking for. Needless to say, the embouchure hole has to be completed first. Then you progress up the flute, opening up each hole in succession.
Since the bore of bamboo may be somewhat irregular and will vary from piece to piece, it is hard to know exactly where to place the tone holes, so you can expect a similar variation on the size of the holes. To my knowledge, Billy Miller use this method of opening up the tone holes with a hot poker, and I suspect that you will see considerable variation from flute to flute, even in the same key.
I use a 7/16" bit to drill the 5th hole on my large bore flutes (F, E, Eb, D, C, B, and Bb). After I finish the hole the nominal diameter of the hole is about 11.4 mm, which makes it a large hole to cover. I don’t think that you would want to make a tone hole much larger than this. I have been using a hole this size for my smaller F flutes, however, I am in the process of R & D with regard to tone hole sizes and fingerhole layout. I don’t believe that you need to have a tone hole that large on the smaller F flute.
Hey Thomaston,
On my Billy Miller flutes, the F# hole on the D flute is actually smaller than the E hole on his F flute. But due to variances in bamboo the hole sizes will also vary a bit.
On My Flutes
D flute F# hole = ~0.39"
F flute E hole = ~ 0.45"
Here’s a picture for comparison:
Thanks for the info! It doesn’t look like I’ll have anything to worry about. 
i have a question for you doug–i have tried to make pvc flutes and they work , but without total clarity or loudness-i notice some holes are lager, the R2 and the L1,L2------now if you made the exact placement all holes COULD be equal sized and function–But is the reason for the hole being larger in some areas to carry the other notes -also your wedge does it cause an increase in airflow
There are two half-tones in the diatonic scale, between the 3rd and 4th and the 7th and 8th notes. The half tone between the 7th and 8th notes of the scale is not a problem. The problematic half tone on a diatonic flute is between R1 and R2. Most flutemakers make the R2 hole large to move it away from R1 and closer to R3. For larger flutes, like the low D standard Irish flute, and especialy for cylindrical-bore flute made from pipe, unless you vary the size of the finger holes in each hand layout, you will come up with a finger hole layout that is not comfortable to cover. The goal is to have as close to an equal distance between the fingers in each hand as possible. Another goal is to have holes that are not too large to cover and not so small that they will only produce a soft tone.