[pianotech] regulating backchecks?

[Gerald Groot]

You need a completely level bench to regulate on in your shop for starters.
I use a large Steelcase desk top leveled on top of cabinets with drawers for
my supplies.  I also use a "Grand Let Off Rack" available from Schaff Piano
Supply.  

 

I regulate let off, key height and hammer line on all end keys prior to
removal of the action.  This way I have my proper let off and (usually)
proper after touch prior to removing the action.  

 

The let off now becomes my hammer line when using the Let Off Rack.  I lower
the rack to the exact same height I had preset for the LET OFF --------- NOT
the hammer string line.  That way, I will have a consistent let off when I
regulate it to just "whisp" the rack.  I use it to also set my hammer line
in the same manner as well as regulation of the back check, drop etc.  

 

That 1/16" difference in back check because of the lowered hammer line to
match let off on the rack will not matter once the action is placed back
into the piano.  It comes out consistently for me every single time.

 

 

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of jim ialeggio
Sent: Wednesday, July 29, 2009 9:57 AM
To: pianotech at ptg.org
Subject: [pianotech] regulating backchecks?

 

My Dear Action Nerds,

As I work to refine my grand regulation skills and procedures, I've run into
a catch 22 regarding grand backcheck regulation which has me scratching my
head.

Here's the problem:

In order to accurately regulate the backcheck, you need to be able produce
the full dip that will occur when the action is bedded in the action cavity.


However, in order to actually adjust the backcheck, especially if the
adjustment is an angle adjustment  the action needs to be pulled from its
bedded condition so yo can get at the backchecks to do the adjustment. Now,
as the action is no longer bedded, you have  thus lost ability to reproduce
the bedded dip and full excusion of the key/backcheck, and you no longer
know what adjustment you need to make.

Similarly, I can regulate a very nice consistent backcheck line on the
bench, with bedding approximately reproduced, but not quite...then the
action goes into the piano and bingo I wasted my time.

What am I missing here?

Jim I 



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