[pianotech] Hammer Line Issue

[David Doremus]

Good words Israel. I want to add one thing to this. The other day I saw 
a Young Chang (U-118, I think) with bobbling hammers on soft play. All 
the regulation seemed to be fine. My first thought was a flaw in the 
butt leather slowing the jack escape. It turned out to be the dampers. 
The springs were way too strong and the lift was set so late that it 
occurred at the point of let off, giving a major resistance right at a 
critical spot. Soften springs and regulate the spoons and it went away. 
This was a new one to me.....


--Dave
  New Orleans.




Israel Stein wrote:
> Hello,
>
> I have followed this with a great deal of interest, and at this point 
> I feel myself compelled to chime in. The hammer bobbling, or dithering 
> or whatever you want to call it (assuming that this is strictly a 
> regulation problem) can be caused by either the keydip being too 
> shallow, or the strike distance being too long. If the problem is the 
> keydip, this in turn could have been caused by the key level having 
> dropped (due to settling of the balance punchings) or  whatever other 
> reason. Before deciding what to do, one should:
>
> 1. Measure the strike distance. If it's 2 inches - the problem isn't 
> keydip.
> 2. Measure the keydip. If it's 7/16 in. (11 mm.) or more - I wouldn't 
> go any deeper...
> 3. Check the key level with relation to the keyslip. Is there a "dip" 
> in the middle of the keyboard? Well, then you level the keys before 
> going any further. Of course to do this, one needs to know the 
> parameters for key level with relation to the balance pins, key slip, 
> front pin, etc.
>