Peter Duggan wrote: ↑Wed Jun 30, 2021 7:22 am
david_h wrote: ↑Wed Jun 30, 2021 3:43 am
How about making a head that fits the PVC pipe and try things like coating the insides of lengths of pipe with glue and blowing sawdust and such like up them?
Isn't this effectively still an experiment in reducing bore volume as well as roughening it?
I would guess that if you are using a cylindrical bore for the test, then any constriction of the bore (reduction in volume) would not be significant if you didn't use a heavy hand with the coating, especially using at least a medium sized bore (19mm or more). So long as the adhesive material is not too thick. Something like thinned epoxy that could wet the inner bore, then introduce the material that is meant to rough up the bore.
I don't know how precise you'd need to be in the execution of such an experiment, depending upon what you are trying to "test". If you are trying to determine whether or not bore roughness affects tone and response, then to me that's a no-brainer. I've done this experiment in some form many times (and anyone who makes a lot of flutes from different materials is going to have observed something similar), and the results are quite obvious. Not delicate shades of nuance in most cases, but rather a hit-you-over-the-head sort of obviousness. But if you are micro-testing the
degree to which said roughness impacts the tone/response, then that's another thing. In the first sort of test, you simply take a headjoint that is well made, cleanly finished, etc. as described above. Use some wood for the body rather than PVC, choosing one that is not naturally smooth when bored out. If I were doing an extreme version of the test I'd use some Pacific Quilited Maple that I have on hand. When you bore it, the inside bore is
totally hairy--literally lots of visible fuzz standing proud of the surface. It's a total mess. Make two of these and don't bother with finger holes. Seal the outside of the bore thoroughly to make sure there are no air leaks through the wood (maple sometimes leaks). Then simply sand and finish one of the bores (I'd use my usual epoxy method). The result will be
glaring, and the question of variations in the players embouchure and such probably won't come into play. That is to say that the difference is so substantial that you won't be wondering if you are just not blowing consistently--it might instead be a question of "I can barely produce a tone on this thing!". As I say, I've seen this effect so many times with so many different woods that it's not a question for me as to whether (or to what degree) smoothness effects performance. It absolutely does make a difference, and the difference is
big.
Of course one can also test nuances by using some wood that is not as awful as the quilted maple. Black walnut would be a good choice, but there are others that will also bore fairly clean but will still show an obvious difference between the finished and unfinished (smooth versus raw) bore.
Determining where the difference starts to vanish is a different sort of experiment and I think that the use of something like PVC would be a good way to test it. Introducing roughness into the bore in small amounts to test if/when you can start to hear it or feel it as resistance. Such a test as that would probably be helped by some type of embouchure control device like Terry suggests. I do think that there is a gray area on the spectrum of smoothness where one will get acceptable performance characteristics and still be able to perceive small differences in timbre, and (as was said earlier in the thread) this is undoubtedly the reason for most makers using a limited number of woods, focusing on those that machine cleanly enough that they will get good results without having to take heroic measures.