Bluthner Patent Action

[piannaman at aol.com]

 Thanks, Ric.? I sort of figured most of this out based on diagrams, sketchy info, and experimentation on a very kindly client's very old Bluthner.? I wasn't sure about the relatively meager key dip.

It was odd lifting the hammer forward the first time I ever saw this thing.? I thought I'd wrecked it!


 


Dave Stahl

 


 

-----Original Message-----
From: Richard Brekne <ricb at pianostemmer.no>
To: pianotech at ptg.org
Sent: Sat, 20 Sep 2008 6:15 pm
Subject: Bluthner Patent Action









Hi Dave?
?

Conceptually, one has to just look at the basic operating principles to 
see how any given action is suppose to work more or less.  Bluthner at 
least gives us that the action regulation is based on a 45 mm blow and a 
9.4 mm dip. As in the modern action these is to be taken as approximate 
guidelines as other things involved can influence how well those two 
figures will work.?
?

All things going after plan then... with a 45 mm blow (set by the hammer 
rest rail and the bore length) you should be able to adjust the letoff 
such that the "jack" is just barely out from under the "knuckle" with 
the bottom of the key barely touching the punching.  That is to say if 
the directions are to be taken literally.  That point is written so 
poorly tho I wonder if whats really meant here is that the jack should 
STILL be (barely) under the knuckle at the precise moment of contact 
between the bottom of the key and the punching. Further depression of 
the key would execute full release and explain the concept of <<no 
aftertouch>>.?
?

Stephen from France sent me some info in German I'll have to get 
decifiered... (Thanks Stephen)  It will take a bit of time to do the job 
nicely but I'll get to it.?

As for the spring on the rocker arm.  Pulling it back towards you will 
increase its holding strength, pushing it forward will lessen it.  It 
should be strong enough to accept a slight drop at let off and be able 
to slightly raise the hammer with any further depression of the key... 
but not to the point of re-contacting the string.... unless for some 
reason you decide that might be a neat effect :)?
?

Cheers?

RicB?
?


?  Hi Ric,?
?

?  The directions do look incomplete and inaccurate in places.? I would?

?  certainly applaud a good instruction leaflet on these actions.??
?

?  What would be helpful to many people--and I put myself on this?

?  list--is tips on bending the springs (which direction, how much,?

?  yadda yadda) and other minutiae that is necessary for this type of?

?  action specifically.?
?

?  I only service one, but I find it very interesting to work on, and?

?  the tone is beautiful.? Though I haven't done a great job of?

?  regulation (yet), it does play nicely.? I was wondering about the?

?  9.4 mm dip and the lack of aftertouch.??
?

?  Thanks,?

?  Dave Stahl?
?




 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20080922/37af2454/attachment.html