[pianotech] treating bridges with CA

Andrew Anderson anrebe at gmail.com
Tue Dec 1 18:21:21 MST 2009


I've tuned a harpsichord with a metal bridge and soundboard.   
Amazingly close to tune six months later too... I wonder why ;-)

I actually liked the sound.  Some odd plectra material though...

Andrew Anderson
On Dec 1, 2009, at 3:51 PM, Scott Gray wrote:

>
> Has anyone ever tried to design a bridge made our of metal?  I know  
> it would sound different but at least it wouldn't crack.
>
> Scotty
>
> Barbara Richmond wrote:
>>
>> Greetings list,
>>
>> When I serviced a church's Yamaha C-6 (beyond warranty) for the  
>> first time a few years ago, the lower treble section was wildly out  
>> of tune. I tuned like crazy and was satisfied with how I left the  
>> piano. About six or seven weeks later, I happened to get called to  
>> tune the same piano for a music competition. I thought, "Ha, this  
>> is going to be a piece of cake." Ahem. Though the same section  
>> wasn't as badly out of tune this time, I was disappointed with what  
>> I found. Yes, there had been a change in season (late fall to no- 
>> doubt-about-it winter), but still, the out-of-tuneness wasn't the  
>> usual seasonal pattern. I had a look at the bridge; there were  
>> cracks--not huge (yet). The church wasn't a regular account of  
>> mine, but I mentioned to the person in charge that there was a  
>> problem that could get worse. She was interested in my opinion and  
>> asked me to make an estimate. I recommended CAing the bridge and  
>> installing a DC system. It's sort of a long story (I won't go into  
>> it), but
>>  eventually the person in charge started calling me to do the work  
>> there and I was asked to do something about the bridge.  
>> Unfortunately, they opted out of the DC system.
>>
>> So, I arrived to CA the bridge. Even with the right applicator,  
>> CAing can be tricky. I was very careful, but still, it's tight  
>> quarters working around strings & bridge pins, and it's a challenge  
>> to keep CA glue from contacting the strings. When a couple or more  
>> drops didn't go where they were intended, I decided if I was going  
>> to sin, I'd sin boldly (thank you Martin Luther). I thought about  
>> some key buttons that went through big seasonal changes that I had  
>> treated with CA when I rebushed them. What an improvement it made  
>> in reducing the swelling and shrinking (thank you, Dan Tassin.) I  
>> also thought about Ed Foote telling about treating the wood part of  
>> old Teflon parts with epoxy and what a difference it made in  
>> reducing the clicks caused by seasonal changes. So, I decided to be  
>> bold and apply the CA ever so slightly below the top surface of the  
>> bridge and have it wick in and up to the bridge pin holes. Then I  
>> applied enough CA so the remainder of the notching was all t
>> he same color. I was looking forward to the next time I tuned the  
>> piano to see if my efforts would improve the tuning stability in  
>> the section, but then there was one of those political bru-ha-has  
>> at the church (one of the musicians didn't know I was the person  
>> who had been working on the pianos, found out, and was angry that  
>> he hadn't been consulted)--so I won't be back there on a regular  
>> basis. Well, these things happen, but I'm mostly disappointed that  
>> I can't track the results of my bet--work--experiment--whatever you  
>> want to call it.
>>
>> Fast forward to today. I got called to come to another church and  
>> another 7 foot piano (this time an 18 year old Kawai) that is  
>> developing those little cracks in the treble bridge--not as bad as  
>> the Yamaha, but still a concern. Here's my opportunity to give it  
>> another try. My aim/goal the first time was to:
>>
>> 1 Keep further damage from occurring.
>> 2 Help keep false beats at bay.
>> 3 See if the treatment helps tuning stability.
>>
>> Has anyone else CA'd a bridge this way and had the opportunity to  
>> see the results of your work?  Comments?
>>
>> Thanks,
>>
>> Barbara Richmond, RPT
>> near Peoria, Illinois
>>
>>
>>
>>
>>
>>

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