Doping pins.

[Billbrpt@AOL.COM]

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


> > > Matt, List:
> > >
> > > I may have missed a post or two on this thread, but is there an 
> advantage
> > > to turning a grand upside down?  I've used CA glue for loose t-pins from
> > > the topside only - and with pretty good results so far.
> > >
> > > Jerry Gravina
> 
> Jerry:
> 
> I like to flip grands because the CA is applied directly to the pins and 
> immediately surrounding area.  I haven't commissioned a study but I imagine 
> that if you apply from the top, some glue gets absorbed by the tuning pin 
> bushing.  If I have room, it usually takes me under 5 minutes to flip a 
> .

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.

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.

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.

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.

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.

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.

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.

 Bill Bremmer RPT
Madison, Wisconsin
 <A HREF="http://www.billbremmer.com/">Click here: -=w w w . b i l l b r e m m e r . c o m =-</A> 

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