Delrin Pratten

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Geoffrey Ellis
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Re: Delrin Pratten

Post by Geoffrey Ellis »

Conical bore wrote: Sun Jan 09, 2022 12:16 pm Dumb question maybe, but doesn't that inevitably lead you back to the 19th Century methods and materials used by modern flute makers offering wooden flutes? Aside from the metal bits -- rings, tuning slide, possible headjoint liner and keywork -- just about everything on a traditional simple system wooden flute is "natural."

You run into the sustainability issue with tropical hardwoods, but there are alternatives that don't involve resin infusion like the Canadian Maple flute offered by Windward. I think that's a heat treatment? Maybe similar to "torrefied" wood used in some guitars these days.
Not dumb :-). I think the answer is mostly, yes. I've taken advantage of all sorts of modern innovations, including epoxies, CA glue, lacquer, dyes, etc.. When I started experimenting with bamboo flutes, I set these aside and confined myself to shellac and some polymerized linseed oil and pine resin. And beeswax. The older finishes are actually quite effective, and you can do a lot with shellac, which is an incredibly useful substance. Twenty years ago I took to using clear epoxy bore finishes for utility, and (to a lesser extent) speed, and the fact that they are pretty much maintenance free. No oiling. They are damn useful and versatile. But they are epoxy, and they are very bad for the flute maker if you don't use plenty of ventilation and/or a respirator. Bisphenol-A, being one of the bad guys. I'm pretty sure I've negatively impacted my health over the years by inadvertent exposure to Bisphenol-A. So I'm considering ditching it in favor of button shellac.

So as I say, I've been rethinking a lot of this stuff.

The torrefied maple is very useful and I stock a lot of it (one of my standard woods). However, depending upon the type of maple you get (hard or soft), the roasting process, while it does stabilize the wood (prevent shrinkage) it also makes the wood lighter and a bit more brittle. It will crack under stress more easily. Not the stress of environment so much as mechanical stress of the kind that happens when making a flute. It's prone to crack when being reamed if the reaming is done to a piece that is not sufficiently girth-y at the time of the reaming. In short, the roasted maple does not feel as robust as maple in its natural state. However, I'm pretty sure that to date I've only used soft maple in roasted form. I'm going to take some very hard maple that I have on hand and roast it myself (my supplier told me I can do it in the kitchen oven) and see what happens. (UPDATE: since writing this I've checked my invoices related to roast maple purchase and I'm pretty sure I've purchased both hard and soft maple. I have not done any sort of conscious comparison of the fragility of one versus the other, but I intend to do so now that I'm thinking about it).

Recycling Delrin: that would be great. And there have been many moments where I have questioned my arbitrary decision about the Delrin. As I say, it is not consistent or even totally rational. If I were really committed to making a change, I'd go 100% natural materials (as much as possible). Choosing one substance like Delrin, that is arguably no worse than some of the other substances that I use, is more reactionary than it is sensible. As I say, there are good things about Delrin, for sure. I wouldn't need an epoxy bore finish for starters ;-)

But being a "natural flute maker" is mostly an illusion. It's not really possible unless you do something like grow your own bamboo (or trees) and make flutes using nothing but hand tools and just finishing it with beeswax (or nothing). If we buy manufactured or processed substances of any kind (including wood), there are all sorts of upstream expenditures of energy and waste, before it ever gets to us. I took a gardening intensive workshop a few years ago offered by Ecology Action. I got an education in what the cost (environmentally) is to produce a gallon of vegetable oils* (soy, linseed, corn, etc.). It made me realize that using linseed oil really isn't any more responsible than using epoxy, though it is healthier for the flute maker. And a strong argument could be made that the epoxy is the more responsible choice! Ironic.

*Most vegetable oils are produced using large scale mono-cropping methods that involves massive use of water resources, chemical fertilizers, large gas-powered equipment, etc. That is before it is transported, processed and refined, shipped using more gas, etc.. The impact on wildlife is profound, as on the soil microbiome.
Last edited by Geoffrey Ellis on Mon Jan 10, 2022 8:22 am, edited 1 time in total.
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Geoffrey Ellis
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Re: Delrin Pratten

Post by Geoffrey Ellis »

Nanohedron wrote: Sun Jan 09, 2022 1:47 pm Harder to deal with, and more insidious, are microplastics from sanding, as Geoffrey has pointed out. But well-equipped workshops use vacuum systems to collect sawdust; why not delrin dust as well?
I think you have the key here. Last time I was sanding some Delrin I thought that I should rig some powerful "spot dust collection" that would grab the fine dust. My current dust collection system is four large box fans mounted in the windows in front of my shop. I open the back door and create a wind tunnel that carries all the dust away. Works great. Except when I sand plastic I'm very conscious of shooting it straight out into the forest where I live. Gives me the heebie-jeebies.
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Re: Delrin Pratten

Post by PB+J »

we just got an electric car. Most of my driving is short trips of under ten miles, a lot of it ferrying my daughter hither and yon. My car was near the end of its useful life, and I just could not stand burning gas at traffic lights and more. But an electric car is only marginally better--the batteries are problematic, thought they can be recycled, and of course the electricity has to come from somewhere. Our local power company's "green" offerings are confusing and misleading. Better would be more walking and bike riding or public transit.

Ethical choices ain't easy!
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Re: Delrin Pratten

Post by Loren »

PB+J wrote: Sun Jan 09, 2022 4:46 pm Better would be more walking and bike riding or public transit.
Unfortunately more and more people are riding electric bicycles. As if all those gears didn’t make pedaling easy enough.

Of course you get a pass if you’re playing a Delrin Pratten while riding your electric bike, because I’m staying on topic.
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Re: Delrin Pratten

Post by PB+J »

With autonomous driving it should soon be possible to pedal and play at the same time
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Re: Delrin Pratten

Post by tstermitz »

Autonomous driving and playing! I'm SO into that.

And electric cars? 120 mpg equivalent means that usages is far, FAR better than gas cars. Manufacturing is far, FAR better than a gas car because the number of parts and steel and etc is so much less.
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Re: Delrin Pratten

Post by Nanohedron »

While I celebrate the resurgence of electric cars and, with much reservation, even autonomous vehicles, I confess to liking the funky allure of vintage stuff and keeping it in use; for example, my colander might've seen time in a sod hut. Still works like a champ. I'd definitely make use of this conveyance below:

Image

I give you - The Velocipede. Not many of them lying about these days, but how utterly cool. Can't play flute while driving it, but that would be overkill anyway.
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Re: Delrin Pratten

Post by Sedi »

Loren wrote: Sun Jan 09, 2022 5:15 pm Unfortunately more and more people are riding electric bicycles. As if all those gears didn’t make pedaling easy enough.
So true. In case of the electric car -- they took something and made it better. In case of the bycicle -- they took something and made it worse.
I use something like this btw:
Image

On the topic of delrin flutes. The question is not whether it can be recycled -- the more interesting question is, why we (in Germany we are very good at that) use a lot different bins and bags to separate our garbage -- only to see the bags end up in another country, ready to be blown into the ocean by wind or just thrown in a river. I don't think the consumer is to blame here.
A better method for building plastic flutes might be in fact 3D-printing as it should produce less waste material compared to using a lathe and making them out of massive blocks.
I like aluminium but it takes a lot of energy to produce. But I don't make them for sale and only made a couple (maybe 20) to give away to friends or use for my own enjoyment. You do have less waste material but you definitely need to wear a dust mask while working at all times (I use one of those that can also be used for spray-painting cars).
I guess a nice material is bamboo (considering the CO2-footprint and availability) -- then using shellac and bindings to make it last longer. Like some shakuhachis are made.
I am contemplating getting a bamboo flute by Barna Gabos. On the other hand -- I have more flutes than I can play. Best for my carbon footprint would be to never get another one :tomato: .
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Re: Delrin Pratten

Post by Terry McGee »

Crumbs, this is a fast-moving thread, even without help from the velocipede!
PB+J wrote: Sun Jan 09, 2022 7:57 am I'd love to hear more of your thoughts on Delrin v blackwood. I'm perpetually torn between tradition and innovation and Delrin seems in many ways to be the perfect material. Also aren't their variants? Other forms of Delrin or other resins that might be more stiff or lighter? I have several "delrin" flutes and they all seem to be slightly different material.
OK. I reckon (after a lot of to-ing and fro-ing) that there isn't much in it. I reckon the Delrin is a little "clearer", the Blackwood a little more "textured". But I reckon I had to work harder to get the Delrin up to that point. You have to be very careful about its preference to "flow" rather than cut. It tries to leave little hair-thin edges at every intersection. Where the hole meets the bore or the surface. Where the bore meets the socket. And so on. They need to be carefully excised, and judiciously rounded. I found the 6th hole the trickiest - it sounded quite airy at first - possibly drawn into greater focus by the greater clarity on say the 5th hole, and the low D. Careful undercutting seemed to make the problem go away.

I imagine every manufacturer might have a slightly different mix for their Acetal co-polymer. Delrin is Du Pont's trade name for their Acetal homo-polymer. It can also be called Polyoxymethylene or POM. I don't think the differences are musically significant to us.
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Re: Delrin Pratten

Post by Terry McGee »

Loren wrote: Sun Jan 09, 2022 8:53 am Terry, have you got a spare flute player about the house? Now would be a good time for a blind listening test between those two flutes. The other player need not actually blind you, you could simply sit with your back turned while they play and switch between flutes.
No spare flute players, but a few pairs of musically sensitive ears. Trying to pin them down is the challenge. If I succeed, I'll get back to you!
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Re: Delrin Pratten

Post by PB+J »

Tank you Terry.

A keyed conical bore flute made of aluminum--what would that sound like, I wonder. I assume--but don't know--that you could cast the body of the flute, like that video of the guy making a bansuri out of chocolate, and then ream and drill it. You could anodize it to interesting colors. It works for whistles. The tube would have to be fairly thick to accept post mounts for keys?
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Re: Delrin Pratten

Post by Terry McGee »

Geoffrey initiated a deep and meaningful discussion on environmental considerations, recycling, dust extraction, etc. I run three separate dust extraction systems, including one for acetal (Delrin). It's what to do with the stuff then. Our nearest town has a "waste transfer station" (rather than just consigning it all to landfill), but doesn't yet include a recycling service for hard plastics like Delrin. But our Prime Minister has made a big thing about plastics recycling (anything to distract questions about Climate Change!) so I'm hoping we might see some movement there in the next few years! I did wonder about trying to melt the leftovers down and recast them into a blank, but then read about it burning with an invisible flame....
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Re: Delrin Pratten

Post by Terry McGee »

Conical bore wrote: Sun Jan 09, 2022 12:16 pm Among other things, I'd be curious about the difference in weight, if any.

Another thing I'd be interested in, is whether you can feel the vibration in the air column more with Delrin vs. Blackwood. I believe that's something we feel with fingers covering the tone holes, i.e. the air column itself and not the material vibrating. So there shouldn't be a difference. But if there is, it would be interesting.
The weight difference isn't as much as I expected - Delrin at 345gms compared to Blackwood at 316gms. So not quite 10% heavier (I expected more like 16% on the figures). And the balance points seemed pretty much the same.

But here's an interesting observation. I have marks on my reamers that tell me: stop when you get to this mark. So I naturally stopped at that mark when reaming the Delrin. But later, I noticed the bore was a smidge smaller. Thinking about it, I can imagine two reasons:
- the poly would rather slip past the cutter than cut, and
- being more flexible than wood, it was able to swell a bit to avoid the cut.

I couldn't detect any practical outcome (eg change in tuning) from this, so it's not a big deal. But an issue perhaps to take into account. I guess I need two marks. And to sharpen my reamers before cutting Delrin!

And I don't think there's any significant difference in sensing the vibration of the air column. But with my toughened old guitarist's and flute maker's fingers, I'm probably not the one to ask! Though I'm oft reminded of one of my long since deceased guru's sayings. Kurt was a German cabinet maker who had emigrated to Australia post WWII and worked near me at first the Research School of Physical Sciences and later at the Research School of Earth Sciences. He had lots of colourful expressions. "Your best eyes are on the ends of your fingers" was one. Translated, it meant "don't look for the quality of finish, feel for it". I still instinctively feel for bore finish.

Another was "Achhh, yesterday the birds were singing on it". Translated it meant "this wood is too green to use now."
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Re: Delrin Pratten

Post by Terry McGee »

PB+J wrote: Mon Jan 10, 2022 4:51 am Tank you Terry.

A keyed conical bore flute made of aluminum--what would that sound like, I wonder. I assume--but don't know--that you could cast the body of the flute, like that video of the guy making a bansuri out of chocolate, and then ream and drill it. You could anodize it to interesting colors. It works for whistles. The tube would have to be fairly thick to accept post mounts for keys?
Well, we do have one point of reference, Clinton's Flute for India. It was silver plated nickel silver, not aluminium, but I reckon it sounded pretty good!

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Re: Delrin Pratten

Post by Sedi »

Ooh, a conical metal flute. I thought there must have been something like that in existence. Way cool!
I tried to simulate the specifications of a wooden flute at least in wall thickness by using a 3mm thick aluminium tube. But due to the bore profile of 19mm there were a few tricks necessary to get it in tune. Plays lovely but the tone is too weak.
On the larger bore 25mm tubes with 23mm ID it works easier to get them in tune with a delicate balance of tone hole size, embouchure size and cork placement.
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