Backfall design

[cverey]

As a complete amateur planning to build a small tracker organ I need some advice on action - backfalls in particular. I understand the traditional fan frame pivoted on wires but what about 'floating' backfalls that pivot on a felt rail. Is the oblique angle of the outer backfalls not taken into account at the pivot? Since the weight of the backfall hangs on the pull down wire to the pallets what should they be made from? I have all the old publications on organbuilding but has anything been written that is more up to date in terms of techniques and materials? "Take a length of 2" mahogany" is not a lot of use! Help!

[Philip J Wells]

As a complete amateur planning to build a small tracker organ I need some advice on action - backfalls in particular. I understand the traditional fan frame pivoted on wires but what about 'floating' backfalls that pivot on a felt rail. Is the oblique angle of the outer backfalls not taken into account at the pivot? Since the weight of the backfall hangs on the pull down wire to the pallets what should they be made from? I have all the old publications on organbuilding but has anything been written that is more up to date in terms of techniques and materials? "Take a length of 2" mahogany" is not a lot of use! Help!

 

I am not sure that floating backfalls and fan frames go together. My understanding is that floating backfalls need the 90 degree pivot angle to operate and would be used in conjunction with roller boards, one roller for each note on the soundboard.

PJW

[David Coram]

A length of 2" mahogany will be a darned sight more stable and much less noisy than anything which has been come along since. Eliminate unwanted movement and eliminate (ok, minimise) friction and make it out all of wood with phosphor bronze ends and leather buttons, and you will have a solution which never goes wrong.

 

Cue MM to sell the benefits of carbon fibre trackers...

[MusingMuso]

A length of 2" mahogany will be a darned sight more stable and much less noisy than anything which has been come along since. Eliminate unwanted movement and eliminate (ok, minimise) friction and make it out all of wood with phosphor bronze ends and leather buttons, and you will have a solution which never goes wrong.

 

Cue MM to sell the benefits of carbon fibre trackers...

 

 

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Carbon fibre s a wonderful material, but a bit expensive. After all, it uses much the same materials as real wood, but in very stable carbonated form, with greater torsional rigidity and almost certainly a resistance to heat and damp which no wood can match.

 

If that is "selling," then so be it......the facts are the facts.

 

There's always cast titanium alloy for the discerning of course.

 

The organ I play uses aluminium tubing, and it never goes wrong. If something works well, why not use it?

 

If something works badly, then something has to change.

 

Between keys and pipes, the organ is only a machine after all.

 

MM

[David Coram]

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Carbon fibre s a wonderful material, but a bit expensive. After all, it uses much the same materials as real wood, but in very stable carbonated form, with greater torsional rigidity and almost certainly a resistance to heat and damp which no wood can match.

 

If that is "selling," then so be it......the facts are the facts.

 

There's always cast titanium alloy for the discerning of course.

 

The organ I play uses aluminium tubing, and it never goes wrong. If something works well, why not use it?

 

If something works badly, then something has to change.

 

Between keys and pipes, the organ is only a machine after all.

 

MM

 

I knew you'd say that, and let me be right there in order to point out that carbon fibre is desperately expensive, as you say, but also somewhat brittle and fragile. I wouldn't use it for anything with a mechanical job to do because of its propensity to just let go and shear or shatter when encountering any kind of lateral force, of the sort which frequently happens when a tuner misplaces an elbow on the way in or out of the case. Wood forgives, is cheap, and has plenty enough strength for me!

[MusingMuso]

I knew you'd say that, and let me be right there in order to point out that carbon fibre is desperately expensive, as you say, but also somewhat brittle and fragile. I wouldn't use it for anything with a mechanical job to do because of its propensity to just let go and shear or shatter when encountering any kind of lateral force, of the sort which frequently happens when a tuner misplaces an elbow on the way in or out of the case. Wood forgives, is cheap, and has plenty enough strength for me!

 

 

=================================

 

 

Ineresting!

 

Our kind hosts have used it of course, at Peachtree Road Methodist church, if I recall correctly. My own knowledge of carbon fibre is restricted to the suspension components and shell structure of Formula One racing cars, which take a hell of a pounding and are subject to exceptional forces, including torsional loadings.

Perhaps the laminations are built up differently to carbon fibre sheet.....I don't know the facts to be honest, and staring at a piece of carbon fibre doesn't tell you much.

 

Expensive it certainly is, because carbon fibre has to be autoclaved over a considerable period, and the process is not easy.

 

Obviously, from what you say,it has its limitations as sliced sheet, but I can't say why without knowing more.

 

The interesting thing about wood, is the fact that it can be part-broken and still remain workable and quite strong, due to the way the fibres interlock.

 

Theoretically, carbon fibre should be as strong or stronger, but theory isn't necessarily the same as reality and everyday experience.

 

MM

 

PS: I used to have a partner who was into fishing, and he used what were called "spun" carbon-fibre rods and poles, which were incredibly strong. I wonder if "spun" fibre isn't stronger, but I shall have to investigate the technology.

[MusingMuso]

I did a bt of digging around late last night, and I ended up more confused than when I started. I had no idea that the technology and materials specifications of carbon-fibre laminates could be so involved.....but it seems to be.

 

That's the trouble with space-age materials.

 

However, the limitation appears to be the types of plastic resins used, so you have to tag plastics technology into the overall equation as well. The addition of carbon-fibre brings enormous tensile strength, but in an organ-action, that's much less important than lightness and rigidity, which good quality wood has naturally. However, I need hardly point out that not all wood is ideal, and an organ-action made from balsa wouldn't last long.

 

As all this is low-priority in my list of things to consider, I shall dig around slowly, and only if I find something interesting to say will I do so.

 

MM

[SlowOrg]

The only organ builder I was aware of until now to use trackers made from carbon fibres is Claudius Winterhalter from Germany.

I know of two of his organs having carbon trackers (Klosterkirche Alpirsbach and the famous Wieskirche). If I'm correct this solutuion is supposed to be especially good for spaces with increased humidity (?).

Here's how such a tracker action looks like (the rollers are obviously made of metal):

 

Wieskirche

 

Alpirsbach

 

M

[tiratutti]

Hello,

 

The only organ builder I was aware of until now to use trackers made from carbon fibres is Claudius Winterhalter from Germany.

I know of two of his organs having carbon trackers (Klosterkirche Alpirsbach and the famous Wieskirche). If I'm correct this solutuion is supposed to be especially good for spaces with increased humidity (?).

Alpirsbach was the first organ of Winterhalter with carbon trackers. The reason was the very wet climate at the medieval monastery church of Alpirsbach. I think he uses it for all his new organs. The organ of Feuerthalen also has carbon trackers. Very nice to play and it sounds marvellous.

 

Cheers

tiratutti

[MusingMuso]

The only organ builder I was aware of until now to use trackers made from carbon fibres is Claudius Winterhalter from Germany.

I know of two of his organs having carbon trackers (Klosterkirche Alpirsbach and the famous Wieskirche). If I'm correct this solutuion is supposed to be especially good for spaces with increased humidity (?).

Here's how such a tracker action looks like (the rollers are obviously made of metal):

 

Wieskirche

 

Alpirsbach

 

M

 

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The American organ-builders Fisk were the first to use carbon-fibre for mechanical-action I believe, and the British company J W Walker & Sons also used it in an American installation.

 

MM

[sprondel]

The only organ builder I was aware of until now to use trackers made from carbon fibres is Claudius Winterhalter from Germany.

Claudius Winterhalter's organs, wherever I heard them or had an opportunity to hit some keys, are excellent, soundwise as well as mechanically. Very little compromise there, if any -- and definitely worth knowing. Among other things, he offers a workable mechnical combination action, thought out very cleverly. Of the smaller companies in Germany, his is certainly among the best. NB: I hold no interest in his work other than that I like listening to a good organ sound.

 

Greetings,

Friedrich

[MusingMuso]

I did a bt of digging around late last night, and I ended up more confused than when I started. I had no idea that the technology and materials specifications of carbon-fibre laminates could be so involved.....but it seems to be.

 

 

As all this is low-priority in my list of things to consider, I shall dig around slowly, and only if I find something interesting to say will I do so.

 

MM

 

 

======================

 

Apparently, there are various combinations of resin types and carbon-fibre weave patterns, which have a profound effect on impact resitance and torsional rigidity.

 

There is also something called "melding," (whatever that is).........

 

Something to do with using metal, epoxy and carbon-fibre in combination.

 

I'm out of my depth!

 

MM