[pianotech] snapping pins

[David Love]

My experience concurs, so the question is why are the pins snapping and what
can you do about it.  One possible explanation goes like this.  When the
original pins are driven into the block they compress the wood in the block
and expand the tuning pin hole somewhat over the length of the tuning pin.
That creates a slight shelf at the bottom of the tuning pin where the
diameter of the hole is somewhat less not having been compressed by the pin.
When restringing over an old block with oversized pins you can sometimes
have problems with rendering if the new pin encounters this shelf.  The new
oversized pin will bind at the bottom of the hole and the result can be
snapping pins.  I've seen this when someone with all good intention used a
new oversized tuning pin that was longer than the original, say 2 1/2"
rather than 2 3/8".  That extra 1/8" of oversized pin (say 3/0 or 4/0 pin)
is now trying to force itself into the original hole drilled for a 2/0 pin.
In the case of epoxy sizing with the original sized pin a similar thing can
happen if a longer pin is used or if the pins that are replaced are driven
deeper in to the block.  

My suggestion would be to try the following, disengage the coils from one of
the pins and back it out 2-3 turns, reengage the coils and bring it up to
pitch and if the snapping still occurs.  It may well put the coils too high
off the plate but back them out far enough to be sure to disengage the
bottom of the pin from that shelf. If that does solve the problem (and there
may be other issues I suppose) then you will have to decide if you can back
out all the pins adequately and still leave them low enough in proximity to
the plate to allow for reasonable tuning characteristics. 

In general, the following guidelines should be used when restringing using
old blocks.  Don't use pins longer than the originals.  Probably better is
to use shorter pins than the original if going to oversized pins.  If using
oversized pins ream or pass a drill bit through the original holes that is
the correct size for the new oversized pin to remove that small shelf and
prevent the bottom of the pin from binding.  

David Love
www.davidlovepianos.com

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Delwin D Fandrich
Sent: Saturday, March 31, 2012 10:26 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] snapping pins

My experience is similar to Ron's. I've never had any snapping pins as a
result of swabbing tuning pin holes with epoxy. Seems to be a valid repair
in cases where replacing the pinblock is simply not going to happen. 

ddf

Delwin D Fandrich
Piano Design & Fabrication
6939 Foothill Court SW, Olympia, Washington 98512 USA
Phone  360.515.0119 — Cell  360.388.6525
del at fandrichpiano.com — ddfandrich at gmail.com


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Nossaman
Sent: Saturday, March 31, 2012 9:06 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] snapping pins

On 3/31/2012 9:35 PM, Leslie Bartlett wrote:
> I quit tuning a ‘30’s Kimball baby grand which if I moved the pin in 
> mid-range enough to go +- 20 cents the pins would crack up to half a 
> dozen times. EVERY pin was that way. Block was not replaced and a 
> highly respected local rebuilder said the guy has simply swabbed epoxy 
> on the holes, so ruined everything. He also did some other stupid
things

..
> Refinished piano, with veneer on lid beginning to come loose, not 
> fixing the problem, of course. But I digress. The issue is the pins

 
> What would cause the swabbing of holes with epoxy (pins seem to be 
> original
> size) cause different response than wicking CA down into the holes? I 
> may be smart enough that I have some idea, but am caught in a conundrum.
> Several years ago I knocked out about 3 pin-sleeves out of sever holes 
> on an old piano. I then filled the holes with epoxy, then redrilled 
> them and those five holes were very nicely tight, turned smoothly, and 
> had none of the cracking/snapping I experienced today. I have no real 
> experience for dealing with this, and would appreciate help.

I've epoxied two blocks with restring, long ago, because they just weren't
possibly going to be paid for to be replaced, and I didn't trust them with
oversized pins. Both tuned very nicely. I see no reason epoxy would make
pins snap, unless it was poorly mixed and rolled thread pins were used. I
also don't have a suggestion for a dependable fix short of replacing the
block. How about finding out from the actual perpetrator instead of the
inevitable "highly respected local rebuilder" diagnosing after the fact,
what was actually done to the block? Sometimes real information provides
real answers that someone's passing opinion (guess) doesn't.
Ron N