Schaff longer new upright spring!

[Richard Brekne]

Hi Julia

I was refering to the center pin for the jack.

My point is, that the jack only needs to get back under the butt 
reasonably quickly to do its job. A moderate tensioned spring, and a 
normal friction toleranced center pin will accomplish that nicely. 
Stronger then necessary springs do not really accomplish anything 
positive at all.  Overly loose center pins are not a good thing either 
for obvious reasons. (they can fall out... hang up on neighbors.. etc)

If the jack puts up too much resistance to being moved out from under 
the butt, then bobbling occurs.  This can either be due to too strong a 
spring tension, or too tight a center pin... or both.

So.... in attempt to keep centers reasonably firm, sometimes these same 
end up too slow on the return... so you see some techs and manufacturers 
employing fairly strong springs to insure fast return. Unfortunatly you 
run into the bobbling problem if one goes too far in that direction. 
Some Yamaha models (and they are by no means alone) seem to be perenial 
borderline cases in this regard, which is what that related thread I 
refered to in my last post was about.

If the springs on your Jansen are in good condition,,, why change them ? 
   Check the jack center pins to 3-4 grams of friction and for firmness 
to be sure.

Cheers
RicB

Alpha88x@aol.com wrote:
> In a message dated 12/17/2004 5:25:45 PM Eastern Standard Time, 
> Richard.Brekne@grieg.uib.no writes:
> 
>> The jack spring and center pin configuration need only provide for a
>> reasonably quick return to firing position. Any increased spring tension
>> or over loosened center pins is really counter productive.
> 
> 
> 
> Greetings,
> 
>            The jacks' and hammers' center pinning on this old Janssen 
> upright are pretty good for its age. Are you saying that if  the center 
> pinning (on the hammers?) or
> (jacks?) gets any looser by more wear that these springs arent a good 
> idea. I am thinking that if I replace these without repinnning 
> everything, and the piano gets more wear to the pins there could be a 
> future problem? Perhaps I should leave well enough alone?
> By the way, by the looks of this one, Janssen made a reeely fine upright!
> 
> 
> Julia Gottchall,
> Reading, PA