Oversize pins in a doped block

[Mike and Jane Spalding]

List,

Today I did the job.  Here's what I did and how it worked:

Removed the old pins (.272) and  bushings.  Reamed the holes with a .271 drill bit.  Swabbed with denatured alcohol to try to get some of the glycerine off the surface of the hole.  Swabbed with PDF (violin rosin dissolved in denatured alcohol).  Installed new bushings soaked per Joe Garrett's method with diluted PDF; wiped up the splash.  Drove new pins, Larudee 3.5/0 with 1/0 tips.  (Paul, these pins are beautiful.  Precisely machined, nice finish.  I can't wait to try them in a block that hasn't been doped!).   Pulled to pitch, tapped down and squeezed the hitch pin loops, pulled to pitch, tapped the bends at the bridge pins, pulled to pitch, leveled at the agraffes, pulled to pitch.  Tunes about the way a doped block tunes, but all the pins are tight enough but not too tight, which I guess means I succeeded in my mission.  My price included a followup tuning in a week or so, I'm curious whether the PDF, when it's thoroughly dry, will improve the feel.

Thanks to everyone who offered advice.  At this point, if I had it to do over, I would go with the largest "Larudee" pins available (4.5/0?) and drill about .020 undersize.

cheers,

Mike


----- Original Message ----- 
From: Mike and Jane Spalding <mjbkspal@execpc.com>
To: <pianotech@ptg.org>
Sent: Tuesday, May 28, 2002 7:47 PM
Subject: Re: Oversize pins in a doped block


> Patrick, Don, Joe, Joe, Dave, and Hans,
> 
> Thanks much for your varied points of view.  While it's not my preferred solution, I am committed to restringing without replacing the pinblock.  Pinblock replacement knowledge and skills are not the problem, budget is the problem.  30 year old Story & Clark baby grand.  What is it worth?  What would it be worth if restrung with a new block?  Does not compute.  I believe I am trying to provide the best service under the circumstances, keeping the best interest of the customer in mind.
> 
> Trying to synthesize all of your experiences into some guidelines for this job:
> 
> 1.  Doped blocks can grip a pin tight enough to shear it off.  Therefore I should not increase the pin size a) as much as for a healthy block or b) at all.  The original pins felt very tight, but grabby, when I removed them.  They are .272 diameter.
> 
> 2.  Joe Goss, you said that CA can "counteract" the effect of the glycerine.  Could you elaborate?  Are you talking about making it tighter/looser, or tuning feel, or what?
> 
> I went to the archives and found Joe Garrett's description of pre-soaking the bushings before installation, which I would like to try.  Joe, how critical is the fit of the pin to the inside diameter of the bushing?
> 
> thanks
> 
> Mike Spalding RPT
> 
> 
>