Dear Mr. Edward Sambell
You opened my mind in many ways.
"In Germany many years ago I asked what tension Several makers They recommended, and the consensus was 40kg., About one half or less what it would be in the piano .." Before completing my project, I will experiment with different amounts of tension, to know how these may vary 40kg ... I use for such a scale similar to those used in fishing (I install two hooks at each end to rotate and place with the wire ...). My project provides a pneumatic cylinder to maintain this tension.
"The winding will be pulled tighter to the core also. The next thing is the speed of rotation.
The copper heats During spinning, and this work hardens it, Thus adding stiffness, Whereas It Should only add mass to the far possible. " I have always used a higher speed to the copper wire of smaller thickness. I will review it - "The problem is the willingness unbearable itchy nose (hehe).
I usually make a clean (almost a polish) using an abrasive sponge Norton (grain :1200-1500). This generates some heat - I have to avoid ...
"The bare core wire at each end of the speaking length Should not Exceed 10 mm in length, this produces the inharmonicity .." I never I have seen about it - thanks!
"The core wire has to be flattened at each end for the winding to adhere, and the length Should not Exceed 12.7mm (1/2 ') for a single winding and 25.4mm (1) "is a double wound string." I have used the hexagonal steel wire as standard. Really a lot easier when you can use it. I will attempt to flatten a smaller area of the wire round .., I also tend to scratch the wire round ....
"Yet it i must still be close to the wound core." This I did not understand well ... (the english)
"I believe most companies These Days spin Their strings automatically." The machine sold by Jhan, uses two servo-motors in sync, and automatically turning on one side ... I would not be able to use the servo-motors (very expensive), but I predict this shift manually. It is best to perform the spin independent advance, than to have to do it in the installation.
"The percentage Diameters for the calculation must be done too, there is the Reduction due to the spinning." You mean that when we chose only one wind instead of two, is better? I realize that use less modern pianos, the two bearings ...
Really grateful
Francisco Motta
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Francisco Motta
Atelier de Pianos Prof. Motta
Belo Horizonte
54 31 34255694
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Original Message:
Sent: 04-17-2012 02:27
From: Edward Sambell
Subject: Bass string Machine
I used to make bass strings, and found that a few basics can make a big difference to the quality . To begin with. stretching the core on the machine to a high tension is a mistake. It makes spinning easier, but results in a stiffer and less flexible string as the windings are tight together. In Germany many years ago I asked several makers what tension they recommended, and the consensus was 40kg., about one half or less what it would be in the piano. . The winding will be pulled tighter to the core also. The next thing is the speed of rotation. The copper heats during spinning, and this work hardens it, thus adding stiffness, whereas it should only add mass as far as possible. The bare core wire at each end of the speaking length should not exceed 10mm in length, as this produces inharmonicity..The core wire has to be flattened at each end for the winding to adhere, and the length should not exceed 12.7mm (1/2') for a single winding and 25.4mm (1)" for a double wound string. This is because the flattening puts the string out of round. One often encounters strings with 2" flats, thus having 4" (100mm) of the string out of round, so they sound awful. Finally, the spinning process requires a good deal of practice, as the copper wire should not be pulled tightly on as it has a low yield point and is easily stretched beyond its elastic limit. Yet it imust still be close wound to the core. I believe most companies these days spin their strings automatically. Scale calculation can also make significant improvement, though there are no standard answers for all pianos. A percentage calculation for the diameters must be done too, as there is reduction due to the spinning.
Ted Sambell
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Edward Sambell
London ON
519-474-7597
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Original Message:
Sent: 04-16-2012 23:19
From: Francisco Motta
Subject: Bass string Machine
This message has been cross posted to the following Discussions: In the Shop and Pianotech .
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Hello list!
I have a very poor English, but I always venture in this forum.
I apologize if I make it clear.
I have a project to manufacture a new machine to make piano bass strings.
I make piano strings for a long time, an old machine, even my grandfather. I installed an engine for many years, and have been very successful for many years.
I wish that my strings were better (it's very dificult to manufacture the the stringbass for small Yamaha upright pianos!)
I have a question related to the ideal tension at the time of winding copper.
I do it intuitively - not too tight but not too light. I suppose, that there should be anappropriate tension for each desired frequency.
I would like to install a pneumatic cylinder to provide this tension in kgf (or N),and steadily during manufacture.
Has anyone reflected about this?
Thanks for any response.
Francisco Motta
Brazil
www.franciscomotta.com
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Francisco Motta
Atelier de Pianos Prof. Motta
Belo Horizonte
54 31 34255694
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