[pianotech] Tuning Failure

[Terry Farrell]

> A vertical piano, of course, has a different type of pinblock  
> construction, but I'm just wondering if some similar fault might  
> exist.


And it is glued to the frame - presumably.......

Terry Farrell


On Jun 14, 2010, at 7:18 AM, Chuck Behm wrote:

> >I've been tuning pianos for 7 years. I'm not unaccustomed to  
> rendering problems. But this is the only time I've been defeated by  
> a piano like this. Tuning pin tightness is good, except for a  
> couple. The bridge is not loose. The plate is not cracked. The upper  
> termination point for the tenor and treble strings is not a cast  
> surface, but a long cylindrical rod in a groove on the plate. The  
> unisons agree with each other, but whole ranges of notes simply will  
> not stay where I put them, even after multiple passes. I was unable  
> to diagnose the problem. What am I missing?"<
>
> Floyd - This situation reminds me of a Fischer grand I worked on  
> years and years ago. It was a really strange thing - every time I  
> went over the treble the bass went drastically out of tune and vise- 
> versa. Pulling the action and inspecting the fit of the pinblock  
> against the flange in the cast iron plate with a mirror I could see  
> that it wasn't a tight fit, but not much more. I went out on a limb  
> and told the owner that I thought there was a problem with the  
> pinblock not seating firmly against the flange, and recommended  
> replacement.
>
> Thankfully, when I pulled the plate for a closer look, I found that  
> the pinblock in fact only touched the flange in 3 spots, but  
> importantly not all 3 at the same time. It was like a teeter-totter,  
> with the middle spot always in contact, but the outer 2 touching  
> only 1 at a time, depending on which way the block was being pulled.  
> Great job of fitting at the factory!
>
> When the block shifted, the dynamics of tension would change on both  
> the treble and bass end of the piano, thus making it impossible to  
> tune.
>
> A vertical piano, of course, has a different type of pinblock  
> construction, but I'm just wondering if some similar fault might  
> exist.  Chuck Behm