Hamamatsu Museum of Instruments

[Richard Brekne]

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Calin, Ron, Dale.....

Overs Pianos wrote:

> .........
> An interesting point about bridge dog-legs. During our many 
> discussions while Ron Nossaman was visiting last week, this topic came 
> up. I have always believed that allowing the dog-leg to extend down to 
> the bridge footprint is undesirable. Ron N has done some testing with 
> a laser which, to him, indicates that allowing the dog-leg to extend 
> right to the panel is unimportant. I have done no testing, having 
> relied only on my own thinking about the dynamic situation of the 
> moving/flexing bridge. So on this matter at present we disagree in 
> theory. I don't have answers on this one since a hunch is not 
> knowledge, so I now have another question which I need to clarify to 
> my satisfaction if possible.

> ---Certainly, manufacturers do move the bridge pin groups to the 
> bridge edges as the scale layout approaches struts to minimise the 
> dog-leg severity.----

Ah.. this was the answer  I was looking for to my origional query. On 
re-reading Dales and Calins posts I see this is what they were getting 
at as well. (sorry Calin.. sometimes easy for me to misread the written 
word)

So... this is all about avoiding a dogleg in the bridge then, and that 
is primarilly an economic (ease of manufacturing) concern.... at least 
according to some. You evidently have some other concerns about dog-legs 
tho if I read you right above.


> But some manufacturers (who should know better) care little if the 
> speaking length is allowed to vary wildly as the bridge passes under 
> the strut. Sure it allows the maker to use a straight bridge without a 
> dog-leg, but it allows for all sorts of tuning stability problems to 
> creep into the picture. We design our bridges with the bridge pin 
> field using to width of the bridge cap to advantage (to minimise the 
> dog-leg), while setting the contact of the bridge to panel using a 
> spring lathe when rebuilding to achieve a smooth contact line between 
> the bridge and panel. We do not compromise the speaking lengths of 
> notes adjacent to plate struts, in an attempt to make bridges easier 
> to manufacture. To me, there's not much to be gained by arriving at a 
> suitable string scale for a design, then allowing the scale integrity 
> to go-with-the-dogs in the name of expediency.
>
This I am a bit unclear on tho... you seem to be saying that the right 
side (of the strut) note does indeed have a longer speaking length then 
the left side note. Why would they do that when it appears they had 
pushed the bridge pin group back as far as possible to begin with ?  

> Ron O.

Cheers
RicB

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