Ancient Backchecks?

[gordon stelter]

Also make sure he balance rail holes aren't "wallered
out " ( as they say in the south ) Fore and aft
movement of the key can contribute to checking
problems.
     Thump

--- Richard Cromwell <rcromwell1@msn.com> wrote:
> 
> Greetings List!
> 
> I have a question regarding this absolute nightmare
> of a piano action (1927
> Chickering - 5'8") I've been fortunate enough to
> have on my bench for the
> past few weeks.  After countless repairs, I get it
> back together and while
> rough regulating it I find it impossible to get
> consistent backchecking.  
> 
> When the action is on the bench, I can get he
> hammers to check, a bit low...
> but at this point I'll take what I can get.  When I
> duplicate the string
> height over the hammers with a jig and then play a
> mezzo forte/fortissimo
> blow - I get mostly no checking and a lot of double
> bouncing.  The jack is
> escaping... so I can only come up with a few reasons
> why this is
> happening...
> 
> 1. The rep spring is too strong... unfortunate
> because they are really
> difficult to get to on this beast. I don't think
> this is the culprit, or at
> least the only one.  My guess is... 
> 
> 2. The fact that the backcheck leather is 80 years
> old, misshapen and worn
> smooth as a baby's bottom where the hammers should
> be making contact.  It is
> almost to the point of being spongy in look and
> consistency.  Not leather
> like at all. This leads me to a few questions... is
> friction in regards to
> backchecking coming more from the wedge like
> positioning of the hammer and
> backcheck when they come into proper contact? Or, is
> it from the tail
> rubbing up against the rough surface of the leather?
> (I know the answer is
> probably a combination of both - but what I really
> want to know is how
> important is it to have good condition leather on
> the backchecks? - thus
> justifying their replacement.)
> 
> 3. Also, at some point in this piano's lifetime a
> well meaning fellow
> attacked it in an attempt to repair it.  I can go on
> and on about the old
> botched repairs I've fixed and crooked keytops
> etc... But I won't.    But
> one thing I will mention is whomever it was put new
> hammers on the old
> shanks, could it be possible that they were bored
> and/or had their tails
> shaped incorrectly (too short) - thus leading to the
> checking problems.
> 
> Now if it is determined that the misshapen and
> ancient backchecks are indeed
> the guilty party and we ignore the misshapen hammer
> tail/improper boring
> hypothesis... I have never had the pleasure of
> replacing a set of
> backchecks, how difficult is it? I removed one as a
> test and it sure wasn't
> easy to get out, I can't imagine it being very easy
> to get the new ones back
> in.  There is little information out there on
> backcheck replacement... so I
> turn to you my esteemed colleagues! Please offer up
> any hints, experiences,
> help, aid, sources of information, etc. that you may
> have to offer.
> 
> Thanks in advance.
> 
> Richard Cromwell
> Cromwell's Piano Service
> Detroit-Windsor Chapter
> _______________________________________________
> pianotech list info:
> https://www.moypiano.com/resources/#archives
> 



		
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