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The Next Great Flute Maker?
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Author:  Geoffrey Ellis [ Tue Dec 25, 2018 11:11 am ]
Post subject:  Re: The Next Great Flute Maker?

Loren wrote:
Wax is lousy, it won’t stay put, particularly in the heat: I’ve worked on enough wax impregnated recorders to see the mess that this makes.

Same with oil, you can soak or force in via pressure or vacuum, but most of it is going to come right back out, unless you add drying agents, which does work.

The epoxy bore sealing you describe is exactly what some recorder makers have been doing for decades. As you have found it works very well, although I never found the process to be particularly fun. Worth the effort though.


Good info about the wax/oil--thank you! I won't waste precious time reinventing that wheel :-)

Yes, epoxy can be messy. I've got a system down now that keeps things fairly tidy, but there is no escaping some mess. Same with resin infusion under vacuum. Very messy business.

Author:  Conical bore [ Tue Dec 25, 2018 12:57 pm ]
Post subject:  Re: The Next Great Flute Maker?

This may be a dumb question: If the headjoint of a flute is coated internally with epoxy -- especially a thick enough coat to be bored and smoothed -- could that cause the same dissimilar rates of expansion that can lead to cracked headjoints on antique flutes with full metal lining? Or does expoxy have a small amount of flex that would keep that from happening?

And is this different with resin infusion? Does that coat both the bore and the outside of the flute?

BTW, I'm not especially paranoid about this, with my main flute being wood with a fully lined (and so far, un-cracked) headjoint. My personal theory is that cracked headjoints with full liners are mostly due to poor storage over enough time in a dry environment. Just curious about the potential difference, if any, with an epoxy "liner."

Author:  Geoffrey Ellis [ Tue Dec 25, 2018 1:51 pm ]
Post subject:  Re: The Next Great Flute Maker?

Conical bore wrote:
This may be a dumb question: If the headjoint of a flute is coated internally with epoxy -- especially a thick enough coat to be bored and smoothed -- could that cause the same dissimilar rates of expansion that can lead to cracked headjoints on antique flutes with full metal lining? Or does expoxy have a small amount of flex that would keep that from happening?

And is this different with resin infusion? Does that coat both the bore and the outside of the flute?

BTW, I'm not especially paranoid about this, with my main flute being wood with a fully lined (and so far, un-cracked) headjoint. My personal theory is that cracked headjoints with full liners are mostly due to poor storage over enough time in a dry environment. Just curious about the potential difference, if any, with an epoxy "liner."


Epoxy won't have that effect, thankfully. The finish coat (like I use) is thin--maybe a few thousandths of an inch--and flexible. When I apply it thinned with alcohol, the first "wash" penetrates the wood, sometimes raises the grain, and gets into the micro-tears that happened during boring or reaming. Once cured, I re-drill and re-ream it, removing any raised grain or micro-fibers that are sticking up. Then another coat gets into any remaining cavities and when re-bored the surface is very, very smooth. A final thin coat when the flute is tuned up lays on the surface like liquid glass, making it very responsive. But that final coat is not thick enough to alter the bore by much. The only down side to epoxy is that if you have a thick inner coating on wood, if the flute is exposed to very high temperatures (in excess of say 120 degrees) there is a chance the epoxy can de-laminate from the inner surface and flake off. I've never tried a stress test to see if this is true (the manufacturer cautioned me about the possibility) but so far I've never seen it happen or heard of it happening to any of my flutes.

Resin infusion is totally different. This is when dry wood is put under a vacuum and submerged in liquid resin. The vacuum draws all the trace moisture and air from the cellular structure of the wood, and once that is complete, the vacuum is released and the wood absorbs the resin. Then the wood is heated to 200 degrees for several hours to cure the resin. Now the wood cells are filled with hardened resin and this increased the weight of the wood as well as radically reducing the mobility (shrink capacity) of the wood. As I mentioned before, some woods are better than others. You can read my blog about the process if you are interested: https://www.ellisflutes.com/blog/vacuum-resin-infusion

I actually use the methods in tandem. I often will resin infuse certain woods, and machine them, but I still use the epoxy method on the inner bore. I do it both for sound and for creating a maintenance free bore (no oiling required since it is waterproof).

Author:  Steve Bliven [ Tue Dec 25, 2018 3:44 pm ]
Post subject:  Re: The Next Great Flute Maker?

Geoffrey Ellis wrote:
I still use the epoxy method on the inner bore. I do it both for sound and for creating a maintenance free bore (no oiling required since it is waterproof).

Now where's the fun in that? :D

Happy holidays.

Steve

Author:  Terry McGee [ Tue Dec 25, 2018 4:54 pm ]
Post subject:  Re: The Next Great Flute Maker?

Heh heh, second Loren on wax. Scraping the river of wax from the bore of a bass recorder that had been left in a hot car did it for me.

Now, it occurs to me that I mentioned density as a desirable further up, but we have to think about why. Three things come to mind:
- less likely to leak through porosity
- naturally takes a smooth finish
- innately strong, so less likely to lose energy from the vibrating air column through flexing.

So it would be interesting to see how that compares with less "ideal" woods cunningly treated. I reckon the treatment should easily satisfy the first two criteria. But it probably satisfies the third too?

It would be interesting to weigh a piece before and after impregnation and finishing to see what the net gain in weight is. But I imagine the resistance to flexing goes up faster than the gain in weight. As long as the treatment hardens in place.

Author:  Tunborough [ Tue Dec 25, 2018 9:47 pm ]
Post subject:  Re: The Next Great Flute Maker?

Terry McGee wrote:
Intuitively, the finish achievable inside the bore and embouchure hole would seem important.
Sorry I'm late to the party with this. I wanted to support Terry's intuition with some lab research reported at the 2017 International Symposium on Musical Acoustics: Henri Boutin, Sandie Le Conte, Jean-Loïc Le Carrou and Benoit Fabre, How Do Wood Polishing and Oiling Affect Acoustic Dissipation in the Bore of Wind Instruments?

Also in: Henri Boutin, Sandie Le Conte, Stéphane Vaiedelich, Benoît Fabre, Jean-Loic Le Carrou. Acoustic dissipation in wooden pipes of different species used in wind instrument making: An experimental study. Journal of the Acoustical Society of America, Acoustical Society of America, 2017, 141, pp.2840. <10.1121/1.4981119>. <hal-01522816>

As I reported in this post:

The researchers asked recorder maker Philippe Bolton to make them tubes of maple, pear, boxwood and ABW, all cut with the grain, plus another of maple cut at an angle to the grain. They measured the rate of attenuation of sound in each tube at frequencies up to 2500 Hz, first in the raw tubes, then after the bore was polished, then after the bore was oiled and dried according to Bolton's recommendations.

The attenuation in the raw tubes depended significantly on wood species: inclined maple tube >> maple > boxwood > pear. Even before polishing, the ABW tube attenuation was only slightly more than would be expected from an ideal pipe.

After polishing, the attenuation in the maple, boxwood and pear was lower and much closer together, although they still ranked in the same order and not quite ideal. The inclined maple tube had improved, but was still worse than the other tubes had been before polishing.

After they were oiled and dried, all four with-the-grain tubes had essentially ideal attenuation. The inclined maple tube had improved greatly, but still attenuated more than an ideal pipe above about 500 Hz.

Author:  Geoffrey Ellis [ Tue Dec 25, 2018 10:28 pm ]
Post subject:  Re: The Next Great Flute Maker?

Tunborough wrote:
Terry McGee wrote:
Intuitively, the finish achievable inside the bore and embouchure hole would seem important.
Sorry I'm late to the party with this. I wanted to support Terry's intuition with some lab research reported at the 2017 International Symposium on Musical Acoustics: Henri Boutin, Sandie Le Conte, Jean-Loïc Le Carrou and Benoit Fabre, How Do Wood Polishing and Oiling Affect Acoustic Dissipation in the Bore of Wind Instruments?

Also in: Henri Boutin, Sandie Le Conte, Stéphane Vaiedelich, Benoît Fabre, Jean-Loic Le Carrou. Acoustic dissipation in wooden pipes of different species used in wind instrument making: An experimental study. Journal of the Acoustical Society of America, Acoustical Society of America, 2017, 141, pp.2840. <10.1121/1.4981119>. <hal-01522816>

As I reported in this post:

The researchers asked recorder maker Philippe Bolton to make them tubes of maple, pear, boxwood and ABW, all cut with the grain, plus another of maple cut at an angle to the grain. They measured the rate of attenuation of sound in each tube at frequencies up to 2500 Hz, first in the raw tubes, then after the bore was polished, then after the bore was oiled and dried according to Bolton's recommendations.

The attenuation in the raw tubes depended significantly on wood species: inclined maple tube >> maple > boxwood > pear. Even before polishing, the ABW tube attenuation was only slightly more than would be expected from an ideal pipe.

After polishing, the attenuation in the maple, boxwood and pear was lower and much closer together, although they still ranked in the same order and not quite ideal. The inclined maple tube had improved, but was still worse than the other tubes had been before polishing.

After they were oiled and dried, all four with-the-grain tubes had essentially ideal attenuation. The inclined maple tube had improved greatly, but still attenuated more than an ideal pipe above about 500 Hz.


Very interesting! This squares with my own experiences with raw versus treated wood. Like the ABW, woods like cocobolo and some of the other very dense and oily woods bore and ream so well that they sound great when the wood is left raw. After boring them, you can look down the bore and they are so naturally polished from the drilling that they have a mirror-like surface.

And again, woods like maple that have unsatisfactory qualities in their raw state change dramatically when the bore is sealed and polished a couple of times.

Incidentally, the resin infusion process with maple changes its character enough that it bores out more like the oily woods. Not quite with the same mirror quality, but much closer. Quite shiny inside before any bore treatment.

Author:  Terry McGee [ Tue Dec 25, 2018 10:41 pm ]
Post subject:  Re: The Next Great Flute Maker?

Very interesting, thanks Tunborough. Sorry I missed your previous post. Probably making flutes or something...

So, as we sometimes joke about ABW: "the next best thing to plastic, eh?" turns out to be not far wrong!

Now, I have a theory about maybe why. We've talked before about how some woods soak up oils applied to them and some don't. ABW is one that doesn't. I've weighed it before and after and there's not much difference.

And when you work ABW, the air fills with a noxious vapour. Well, I find it noxious. If it were not for very good dust extraction, I wouldn't be able to work the stuff at all.

So, I reckon it's pre-loaded with a resin that clogs its pores making it naturally bug, water and oil resistant, leaves a naturally polished surface, but which volatilises during machining operations to release the aforementioned noxious vapour.

It may not be very hospitable to bugs, but it certainly sets a high standard as a woodwind material!

Author:  paddler [ Tue Dec 25, 2018 11:50 pm ]
Post subject:  Re: The Next Great Flute Maker?

Thanks for the link to the paper Tunborough! I think its results address some of the questions we have, specifically
about the potential for making a good sounding flute out of these less dense woods. They seem to suggest that with
sufficient attention paid to polishing the bore, there is little theoretical reason for the type of wood used to degrade
the sound drastically, at least when we are restricting our attention to fine grain woods like fruit woods and such.

Although there are some caveats, such as (a) how much measurable difference is there between a great flute and
a mediocre one (i.e. maybe the small differences between the polished versions of these woods are still significant
enough in the perceived performance of the flute), and (b) for conical bore instruments the experimental set up
in this paper, which assumed a cylindrical bore aligned with the grain (i.e. no exposed end grain) is not accurate.
Only the figures for the "inclined maple" show the effect of end grain on the bore surface. It would have been nice
to see comparative results for inclined African Blackwood, Boxwood and Pear wood.

But, the results do match some first hand experience I have. I have been prototyping some flute designs over the past couple
of years, using some English hawthorn wood, which I have an abundant supply of. I gathered, milled and seasoned
it several years ago with the idea of having an supply of cheap wood I could use for prototyping purposes, so as to
delay eating into my stock of traditional flute woods. This hawthorn wood has properties similar to pear wood, but
looks nicer. The resulting flute ends up looking quite a lot like a boxwood flute. The wood has a very fine grain
and takes a nice finish, especially after a few applications of tung oil.

A flute made from this wood is very light in the hand. Due to preconceptions I had about the importance of density,
I didn't expect it to sound very good. However, I have been quite surprised at how good they can sound. It is
possible to make a very nice sounding flute out of this wood.

This experience has convinced me that from a purely acoustic perspective, density is not as important as other properties,
such as how fine grained the wood is and how fine a polish it will take. Basically, from an acoustic standpoint this wood seems
to be a pretty good substitute for boxwood, and we know that boxwood flutes can sound quite lovely.

But the trouble is, acoustics are not the only important factor here. In considering what materials to use for flutes that I would
feel comfortable offering for sale, I quickly become concerned about other factors like stability, durability, etc.

Polishing a bore, and perhaps adding a hardened surface finish to it, can make a flute sound great, but that will not
make it any more dimensionally stable or durable. Resin infusion addresses the stability worry, but that will not necessarily
make the wood a lot stronger. These are good ideas, but each method addresses a different concern. And the
reality is that in the end, all of the concerns matter.

For these kind of reasons I've been slowing coming to the conclusion that the main reason flute makers have gravitated towards
woods like African Blackwood is not so much because it sounds better (maybe it does, but the differences are marginal, and
different people have different preferences with regard to what sound better to them), but because it is exceptionally stable and
durable and has great machining properties. And some of those properties do seem to correlate well with density.

Author:  Terry McGee [ Wed Dec 26, 2018 1:34 am ]
Post subject:  Re: The Next Great Flute Maker?

And of course, we expect our flutes to look well, so that's a factor too. Felix Skowronek spend time in the West-Australian Goldfields region collecting timber samples that matched his technical considerations. But they were mostly very boring looking, whitish Eucalypts. Fence post material.

Author:  PB+J [ Wed Dec 26, 2018 6:52 am ]
Post subject:  Re: The Next Great Flute Maker?

I can't help but observe that in terms of density, capacity to machine smoothly, and resistance to cracking Delrin seem to be the optimum material. And yet I sit here with what is said to be a good delrin flute wondering about wooden flutes.

There's a brand of guitar picks, "blue chip," that cost 35-75 dollars per pick. I did some research on my own and discovered they were made from a DuPont product called "VCespel," which you can buy in rod stock but which costs astonishing amounts of money, like so: https://www.amazon.com/Vespel-SP-1-Polyimide-Round-diameter/dp/B00DXKFV80

I bought a very short length of 1 inch diameter rod for a great deal less money and made a bunch of picks and they did have very interesting physical and acoustic properties

Point being the world of materials science probably has other materials interesting that might make good flutes. But not at the price of Vespel!

Author:  Geoffrey Ellis [ Wed Dec 26, 2018 8:51 am ]
Post subject:  Re: The Next Great Flute Maker?

paddler wrote:
For these kind of reasons I've been slowing coming to the conclusion that the main reason flute makers have gravitated towards
woods like African Blackwood is not so much because it sounds better (maybe it does, but the differences are marginal, and
different people have different preferences with regard to what sound better to them), but because it is exceptionally stable and
durable and has great machining properties. And some of those properties do seem to correlate well with density.


Exactly. This is the very assertion Tom Ridenour made in his article (The Grenadilla Myth). Woodwind makers chose ABW for non tone-related reasons, such as machining properties, stability, durability, ease of matching pieces (aesthetics), etc.. His own assertion in the article is that (for clarinet making) Honduran rosewood was tonally superior to ABW as was ebonite (natural hard rubber).

Many of the woods that I use for single piece flute bodies (anything where joints are not involved) are not dimensionally stable at all! They shrink a LOT in some cases (as well as warping on the longer pieces). Stability is a big deal and a very attractive feature in a wood, equal to tonal considerations I'd say.

Author:  Geoffrey Ellis [ Wed Dec 26, 2018 9:03 am ]
Post subject:  Re: The Next Great Flute Maker?

PB+J wrote:
I can't help but observe that in terms of density, capacity to machine smoothly, and resistance to cracking Delrin seem to be the optimum material. And yet I sit here with what is said to be a good delrin flute wondering about wooden flutes.


I think that you are correct. Delrin is a great flute material for a multitude of reasons. It has a high degree of acceptance in the world of ITM compared to other flute markets. To illustrate, several years ago when I was working with Ron Korb on developing a line of Boehm headjoints, my original idea was to make them from Delrin. I sent Ron some prototype headjoints made from Delrin and he loved them--said they sounded amazing. But he said that Boehm players would never buy them so don't even bother making them. When I asked why, he said "Because they are plastic. No one will touch plastic." It turns out that he was right. We handed them around to a few professional players that he knew and it was clear that plastic headjoints would never get much traction. I believe this is why it took a lot of struggle for Guo flutes to catch on, and they had to find some unusual ways to market them (such as targeting college marching bands who could get instruments made in their school colors).

It's possible this prejudice can be overcome in time, but it really depends upon the musical niche. For Irish flute players, there would be good reasons for a flute made from Delrin, since the entire flute would be made from it. For Boehm players, less so. They love wooden headjoints, but if they can't get wood they prefer metal. Why would they bother with plastic? It's that sort of mind-set.

Author:  Steve Bliven [ Wed Dec 26, 2018 11:52 am ]
Post subject:  Re: The Next Great Flute Maker?

Geoffrey Ellis wrote:
With Delrin there is waste, of course, because of the subtractive process of machining it, but it has the advantage of being something a maker can use in lieu of wood, working with the exact same tooling set up and not having to master mold making. But it is slippery. ... And I wonder about the future of plastics from a perceptual standpoint. My own experience is that the majority of players prefer wood to plastic of any kind (or in the case of Boehm players, they prefer metal or wood to plastic). I've been curious as to whether this perception of plastics will get better or worse in the future. ... On the other hand, plastics are also an eco-disaster that is very much in the consciousness of the younger generation, so they might look askance at them.

But hopefully people will be able to distinguish between single-use plastics of the type that are filling the ocean and the higher density type that are being turned into instruments, and are therefore most unlikely to be swallowed by some innocent sea turtle. I would not want to work exclusively in Delrin, but I can't deny that it is a material with a lot of utility. ...

I just received a Delrin flute from Vincenzo Di Mauro. He seems to have solved the "what to do with the waste", as well as the "where to put the waste", issues by using the shavings as packing material. None of them :swear: Styrofoam peanuts that electrostaticly stick to everything...

Image

Not only did it protect the flute in shipping, but now it's exported out of Ireland and is my concern. :D Luckily, I know an artist who would love to work this into some of her work....

Also, Mr. Di Mauro didn't polish the flute but rather apparently ran some coarse sandpaper lengthwise which offers the appearance of wood grain as well as helping with the grip.

So kudos to Mr. Di Mauro for his solutions.

Happy holidays.

Author:  maestrosid [ Wed Dec 26, 2018 1:11 pm ]
Post subject:  Re: The Next Great Flute Maker?

This has been a fascinating discussion on materials for those of who simply play flute with no maker's aspirations. It seems to me that CITES regulations have had an impact on the use of ABW. The last flutes I purchased from overseas were mopane, which seems like a good option and allowed me to bypass CITES regulations, yet I am not seeing it mentioned here except in passing. Any thoughts on mopane?

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