Hammers blocking in Seiler uprights

[piannaman at aol.com]

Hello Roger,
 
Thanks for the detailed response.  Very interesting stuff.  I'll have to get a 4mm reamer and try this out.  You've done all of the legwork already!
 
If I'm reading this right, what's happening is the key is not rocking correctly at the pivot point/balance rail due to the overly tall hole, which essentially means the key is acting shorter than it really is...right?  And manufacturers have counteracted this by increasing dip to 11mm...?  
 
I think I'll buy a Seiler just to experiment with in my garage....:-)
 
Thanks again!  Your generosity is always appreciated!
 
Dave 
 
-----Original Message-----
From: Roger Jolly <roger.j at sasktel.net>
To: Pianotech List <pianotech at ptg.org>
Sent: Fri, 07 Apr 2006 10:58:56 -0600
Subject: Re: Hammers blocking in Seiler uprights


Hi Pianoman,
                          You may have several issues working against you.    I have just finished do some research for SMC on vertical pianos that had similar problems,   The general consensus was that there was a geometry problem..

After checking all kinds of parameters the solution ended up being very simple.

The Balance rail hole was way too tall. ( 7mm on some models.)  Ream the B/R hole down to 4mm and reduce the dip from 11mm to 10mm.  The problem pianos play beautifully.

If the hole is too tall, the pin starts to bind in the hole making let off and after touch very ill defined.  This will be very noticeable on ppp playing.

Balance rail hole height, dip, F/R cloth punching, and after touch are all interactive.

>From empirical data from 1000's of keys measured, I have come to the following conclusion.
A spruce key needs only 4MM of key height,  Maple shoe keys 3mm height.
The only manufacturer  that I have found to be consistently correct has been the Yamaha Corp.
Samick after last August key production, has been corrected, and a separate QC check is in place to monitor the measurement.

This single measurement is probably the most critical of all measurements in how any action feels. It also has a dramatic effect on note to note consistency if the mortice is poorly machined.

On the manufacturing side,  rate of feed, frequency of changing the router bits, chip out cleaning etc.  All have an effect on the quality of the mortice.

The only visible problem.      mmmmmmmmmmmm     Your quote:  The hole height is hidden in the bottom of the mortice. ;-)

The reaming tool is available from Pianotech,  or Jurgen

Keep your finger firmly on the bottom of the hole and ream away until the tip touches your finger.  It only takes 30min to do a key board.


Hope this helps
roger


At 12:22 AM 4/7/2006, you wrote:

Hi List,
 
I took a breather from the list because business has been pretty good, and wht do I see in my mailbox?  637 messages from pianotech...  Wish I'd had the time to read them all!
 
I have recently encountered an interesting problem in a few Seiler uprights.  Last week it was in a 132, probably 2 years old.  This week it was a 122, similar vintage.  Both were purchased as new from a dealer within the last 7-8 months.  I've also seen this problem with a few Seilers of slightly older vintage.
 
What's happening is that the backchecks are checking the hammers a bit too close--like right into the string, if you push on the key a tad, or on a soft blow where the hammer rebounds slowly and gets smushed into the string by the backcheck.
 
There is adequate lost motion.  In one of them, there was negative lost motion, but the problem persisted after regulation of lm
Let off is good, right around 3-4mm
 
The only VISIBLE problem is the checks are regulated way too close.  
 
After making the the lost motion was okay, I regulated so checking around 10 mm.  It works fine.  It's strikes me as odd that this would happen, because they weren't that way at the first tunings.  Granted, we are having a wet winter, but I can't fathom how humidity could cause this. They are both in relatively stable environments.
 
About 4 years ago, I dealt with a Seiler that had this, and many other regulation problems seemingly caused by environment.  AFter regulation, the piano has been quite stable.
 
Anybody with similar experiences with these pianos?
 
Have a great weekend, 
 
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