I am thinking of making a G flute (PVC) that has smaller finger holes for my daughters because they can’t cover the larger ones on the flutes I have made. What is the impact of making the whole smaller (obviously, other than the placement)? Quieter? Harder to play?
Any help and suggestions would be appreciated.
Both quieter and easier to play. But don’t make the holes too small. Minimum ca one third of the tube inner diameter. For a G flute a tube ca 16 to 18 mm inner diameter may be best, especially for kids.
~Hans
I am sort of the expert on this here and am feeling verbose on a week in which Lyme Disease is giving me a welcome break!
General principles that I follow (trade secrets here - if you are a flute maker - avert your eyes):
General principle - farther up the hole the smaller it needs to be. Farther down the larger. There is a useful range in terms of placement and fingersize for each hole, and systematically.
I locate the G and the C# holes in “permanent” ideal locations, then move up and down the other 4 as needed, using the above principle. Usually I space these evenly as that is more comfortable for the hands. This is challenging for the bottom hole!
Holes need not be straight in line to be playable. I find arranging them in arcs, including spacing the middle finger farther away from the hand helps. This brings the hand closer to the 3rd fingerhole.
Where it gets complicated is when the fingerholes have to play the second octave, or if one wants to get a strong bottom D on an instrument, or in my case - both of these desires fulfilled. This has involved years of iteratively tweaking my flute designs and considering every flute a prototype for the next. That I didn’t number my flutes will mess it up for the musical historians of the future to sort out how I did this - but I had to leave them with something to do!
Generally get the first octave to play in tune with itself and then see what you can do to correctly tune the second octave with respect to the first. With holes with no undercutting on a taper bored flute, the 2nd octave will play in flat, especially at the top. Undercutting the holes, sometimes steeply, will correct this. It depends upon the bore as well. See Benade’s Musical Acoustics book on how to also work with the bore on adjustment of tuning between octaves. He discusses chambering quite well.
Tuningwise, with respect to a tuner, the 2nd octave should “look” about 20-30 cents sharp to sound in tune.
To answer your question - smaller holes improperly designed do minimize the tone some. This is overcome though once the flute is ergonomically designed for the player who relaxes more into it and can pleay it easily. Undercutting holes opens up the tone tremendously which is how I get my small handed versions to play just as well as my regular handed versions.
I’ll answer any additional questions (including other makers - it would be nice to discuss something real here) as time allows.
Casey
I promise to never use your suggestions. 
Thanks for the tips above. I have actually played around with undercutting the finger holes but my playing is not strong enough on the 2nd octave to really test this out. I am looking for someone local that can test out my flutes to help with this…as well, I am practicing about 2 hours a day. 
For now, all I am trying to do is make a flute that my daughters can play. They are 8 and 10, so the hole size is rather important. I just was not sure if making a small hole will mean that air has too hard a time flowing through it and it just wont work.
Hole sizes will be:
3/8 (embouchure)
5/16
5/16
5/16
5/16
3/8
1/4
While these will be made for my daughters, if they work I will include them as an option for sale. The flutes I am going to be making are meant for beginners and obviously I would like to be able to sell to children as well.
Off to experiment!
Well, just made one and it isn’t too bad. I had to undercut the first 3 holes a fair bit to bring it up in pitch. PVC is somewhat thick so perhaps it was impeding the air a fair bit.
I am still adjusting it and will probably make a few more yet but it seems to work pretty well with these smaller holes. When my daughters get home…that will be the real test.
I don’t understand this at all!
Cheers
Graeme
How do you determine the “ideal location”? Do you do it with regards to an acoustically optimal tonehole size? Or to what kind of tonehole size?
Generally get the first octave to play in tune with itself and then see what you can do to correctly tune the second octave with respect to the first. With holes with no undercutting on a taper bored flute, the 2nd octave will play in flat, especially at the top. Undercutting the holes, sometimes steeply, will correct this. It depends upon the bore as well. See Benade’s Musical Acoustics book on how to also work with the bore on adjustment of tuning between octaves. He discusses chambering quite well.
What is the best way to raise second octave notes by undercutting, and not raise first octave notes? How much undercutting (angles) and on what sides is required for this? So far I have been using ca 45 degree undercut on east, south and west side of tone hole, but not north (towards the embouchure hole). Is there a mathematical formula to help determine the effects of undercutting? I have not got Benade’s book.
Tuningwise, with respect to a tuner, the 2nd octave should “look” about 20-30 cents sharp to sound in tune.
Please explain this paradox!
Thanks!
~Hans
A lot of it including locating the ideal hope position depends upon trial and error and much experimentation and willingness to ruin everal instrument attempts. Practice Practice Practice. And some common sense - you don’t want to lcate the G hole to find that you have committed the the other two holes to “impossible” positions.
By “visual” I mean how the tuning looks on an electronic tuner dial - versus what one is actually hearing
Again, look up Benade and read his principles of hole location etc. Or if you want some mathematical fun, Nederveen.
too many possibilities…
thanks!
I’ve been experimenting with undercutting tone holes and looking for the resulting tuning differences and I haven’t (so far at least) been able to see any consistent effect. I’ve been trying to use RTTA and a “blind” tuning process to try to eliminate any embouchure effects, but I admit I haven’t done enough to have any confidence in my results.
In your experience, how much impact can undercutting have? E.g., can you raise a tone hole (say) 20 cents in the second octave? What’s the impact on the first octave tone?
Tuningwise, with respect to a tuner, the 2nd octave should “look” about 20-30 cents sharp to sound in tune.
I’m also curious about this comment. Given that many flautists blow sharp in the second octave I’d expect you’d want to do just the opposite.
On the original question (size of toneholes), there’s clearly a lower limit on usable tone hole size where the quality of the tone sounded becomes muffled or poor. In my experimentation, I’ve found (maybe not unexpectedly) that this limit is lower the higher the tone. Pretty small tone holes seem to work well in the second octave, and better on the left-hand holes in the lower octave (on a D flute). I might guess that you could get away with pretty small tone holes on a G flute, particularly on the left-hand holes.
In testing out the G I made it is noticeably flat as you get into the left hand notes (I used the flutomat calc). I will be reaming these later to see how it works out.
One thing I noticed is that the Fnat needs to be just the 2nd hole…no idea why. The sound is really quite nice though with the lower notes sounding nice and full.
I was thinking I would scrap this particular design though and try it with a 1/2inch CPVC pipe instead. The only thing I am worried about is if this will make the flute much harder to get a decent tone (because of a decrease in wall thickness) for children just learning.
More embouchure and fingerhole wall thickness is a definite help in tuning and voicing purposes. For a Concert D flute, 5mm of wall thickness is pretty good. There are probably strategies of gluing or adding resin to build these up.
However, do your kids a big big favor and use some bamboo instead! Keep them away from the pthalates and other damaging chemicals these plastics release. A Garden Center should have some decent bamboo. Look for some in the 3/4" to 1" range. Look elsewhere for bamboo flute making directions online - there is certainly a bunch, including stuff by Mark Shephard. The endercutting rules still apply.
If it grows in your area Cane (Arundo Dinax) is another good reed to use. I saw a lovely set of flutes made in SE France from this cane, normally used for clarinet reeds. Each was reamed with a slight tapered bore and each played superbly. Guy Bertrand of the group Lo Jai owned these and recorded much with them.
I do not like working plastics and now with a struggle with Lyme Disease I am even more chemically sensitive and vulnerable. You don’t want to risk aything with your kids. So seek out these other alternatives, please!
Casey
While I’m not adverse to using PVC (I don’t have any chemical sensitivities) and in fact play an M&E which is made from food grade PVC, bamboo flutes are fun to make and play and look great.
Casey is right that working in bamboo is as easy as working in PVC - you will crack a few at first but it’s so cheap it doesn’t cost much to learn as you go. A lot of the online sights rely on using the end of a node instead of cork for a stopper…personally, I ignored that advice and cut the end longer and used a small piece of cork - which allows some adjustment. Unless you have a piece with the nodes far enough apart, you’ll need to burn through or drill through the membranes…and this also is easier if you don’t use the end node for the cork since you can access both sides of the flute body with a long, narrow drill bit. One final tip is to put something inside the bore of the flute when burning or drilling (either will work if you have good drill bits) so that when the burning poker or drill bit goes through it doesn’t hit the far wall of the flute and crack it (I used broken pieces of bamboo since they’re already curved and fit well).
One nice thing about bamboo is many pieces have a very slight taper which helps a tiny bit with the second octave (undercutting tone holes helps much more).
Eric
Ooooooohhhhh! I might just give this a try!!
My guess is that the end result is far more inconsistent, but that can be part of the fun.
Thanks guys.
hmmmm…looks like bamboo may not be so easy to find around here. I just went to 5 stores and didn’t really find what I needed. One garden centre had some that were just a bit too small and a craft store had some that were too large and overpriced to boot. 
I will try calling from carpet places. Any other suggestions?