[pianotech] Scaling Help

[Albert Picknell]

Contributing to the problem is the fact that manufacturers of both the American sizes and the metric sizes use the same gauge numbers, while the actual diameters are different.  This can cause confusion.  For example, if you take a roll of #13.5 (American) wire from Mapes and a roll of #13.5 (metric) wire from Roslau, the Roslau wire will be .0005" smaller, which puts it exactly halfway between #13 and #13.5 Mapes.  Have a look at the attached Excel spreadsheet.  If you compare the numbers in the far left and far right columns, you'll see that as you move toward the larger wire gauges this difference increases, so that Roslau's #22 is actually closer in size to Mapes' #21.5.  However, the jump between #22 and #23 is not the same under the two different systems; this brings the two systems closer into line, so the last few sizes are practically identical.

My approach would be to measure all the string lengths, enter them into a scaling program, and rescale the whole thing.  If that's not an option (or not a practical one anyway), and the original wire is metric and the wire you're replacing it with is American, I would just go with what's closest.

Cheers,
Bert


--- On Fri, 4/1/11, David Love <davidlovepianos at comcast.net> wrote:

> Yes.  That chart is a full half
> size different than the gauges given for
> Roslau wire sold by American suppliers.  Best thing is
> not to trust gauge
> markings on the plate.  Measure the wire with a
> micrometer and convert
> depending on your supplier's protocol.    
> 
> If you are buying Roslau or Mapes wire from an American
> supply house, .043
> will correspond to #19 gauge.  Pianos manufactured in
> Europe or other parts
> of the world may well have a different gauge
> standard.  
> 
> David Love
> www.davidlovepianos.com
> 
> 
> -----Original Message-----
> From: pianotech-bounces at ptg.org
> On Behalf
> Of John Delacour
> 
> Only Americans use the American wire gauge.  Everyone
> else uses the 
> sizes you'll find here:
> 
> <http://www.fletcher-newman.co.uk/catalogue/piano_wire_strings/index.html>
> 
> JD

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