Doping pins.

[Gevaert Pierre]

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Dear list,

What is CA glue?
Are there different qualitys or brands that are better to use?

Thanks,
Pierre Gevaert.
  ----- Original Message -----=20
  From: Billbrpt@AOL.COM=20
  To: pianotech@ptg.org=20
  Sent: Saturday, June 15, 2002 4:19 PM
  Subject: Re: Doping pins.


  In a message dated 6/15/02 8:47:25 AM Central Daylight Time, =
ptuner@optonline.net (Matt Wynne) writes:=20



    > > Matt, List:=20
    > >=20
    > > I may have missed a post or two on this thread, but is there an =
advantage=20
    > > to turning a grand upside down?  I've used CA glue for loose =
t-pins from=20
    > > the topside only - and with pretty good results so far.=20
    > >=20
    > > Jerry Gravina=20

    Jerry:=20

    I like to flip grands because the CA is applied directly to the pins =
and=20
    immediately surrounding area.  I haven't commissioned a study but I =
imagine=20
    that if you apply from the top, some glue gets absorbed by the =
tuning pin=20
    bushing.  If I have room, it usually takes me under 5 minutes to =
flip a=20
    grand alone
  .=20

  Although I rarely get involved with something like this, there is a =
time and place for everything.  There is a friend of many years who has =
a Lyon & Healy grand that has been sitting around in unplayable =
condition for about 10 years.  It really needs rebuilding but there is =
no way he could afford that.  The soundboard and bridges are in flawless =
shape.=20

  Upon inspection, the pinblock looked good too with no visible =
delamination but many of the tuning pins were uncontrollably loose.  I =
decided that this was a good candidate for CA glue pinblock doping.  =
Last weekend we did the doping job and today I will go finish the =
project.=20

  I look at it from a theoretical point of view:  couldn't I surround =
more of the pin more effectively by first turning the piano over and =
doping from the backside, then from the top?  Not only did this work =
very well but upon doping from the backside of the pinblock, there was =
some seepage through to the edge of the pinblock between the bottom two =
laminations.  This told me that even though the block was not *visibly* =
delaminating, it was in fact very weak, enough so that the glue seeped =
through.=20

  The whole idea of using CA glue is that this substance will fuse =
together any structurally weak parts of the block.  The other kinds of =
dope which are merely intended to swell the wood cannot provide any =
structural strength the way CA glue does. Upon doing the first rough =
tuning, each pin was stuck hard and took some real muscle to move it.  =
But afterwards, the feel was amazingly normal and smooth (not jumpy as =
might be expected) with very high torque, about what you'd expect from a =
new pinblock.=20

  The hammers were worn enough to need replacing but the customer not =
having enough to pay for that, I just decided to give them a good =
filing.  The let off was about 1/2" but after a good knuckle bolstering =
job, it brought the let-off right up to where it should be with a few =
hammers even blocking slightly.  It lifted all the shanks off the rest =
rail too. Today, I'll go over the regulation but I don't expect to have =
to do a lot.  I'll give it two more tuning passes (a total of 4).  We =
had to overhaul the pedal box but aside from that, just a few basics =
like this will bring the old grand of fairly good design back to life =
for a few hundred dollars.=20

  Another younger tech who is still learning the trade is participating =
and the customer himself did the doping.  We had fans blowing full force =
with all the windows open to evacuate the fumes which were pretty =
intense at times.  Like the recent thread on Spinet Grommets, involving =
the customer of modest means and maybe another tech who is learning the =
trade can be a way of lowering the costs to the customer and having that =
person be really grateful.=20

  Everyone enjoyed the session, we broke for lunch and another couple of =
iced tea breaks which we'll do again today and have a very well spent =
day.  Tonight, undoubtedly, there will be music flowing from that house =
all evening long.=20

  Bill Bremmer RPT=20
  Madison, Wisconsin=20
  Click here: -=3Dw w w . b i l l b r e m m e r . c o m =3D-=20

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