center pinning question

[Allen Wright]

Don,

That's basically what I meant with my first possibility ("nap of the  
cloth changing"), although you express it much more clearly. I looked  
to see if the pins were roughly cut on the ends, but they actually  
looked like pretty clean cuts. It's quite possible the cloth is being  
roughed up by either my extracting pliers, or a rough pin end, but it  
just surprises me how much more friction was being added; we're  
talking about going from 12 swings )maybe more) of the hammer to  
noticeably tight (coupla swings) just by replacing the pin. Have you  
ever experienced such a difference?

Your idea of the sharp tip catching makes sense, too, although almost  
every pin I replaced behaved like this, so maybe that's not as likely.

Well, the repinning went fine, so it's not really a problematic  
situation I'm inquiring about here. Just sort of mysterious. It'd be  
nice to understand what's going on.

By the way, by chance I happened upon your very first PTJ article on  
center pin broaches (where you instructed us how to make our own)  
recently, and enjoyed it very much. The broaches certainly make  
repinning a lot more systematic and consistent.

Thanks,

Allen Wright


On May 15, 2008, at 5:39 AM, Don Mannino wrote:

> Allen,
>
> It's hard to say for sure, but a few more possibilities:
>
> - Pushing the old pin out disturbed the cloth fibers  
> substantially.  This can happen especially when the original pin  
> was cut on both sides, and you have pushed a 'burr' through the  
> bushing in the process of extracting the pin.  The pin extraction  
> tool could also theoretically be rough or bent at the tip,  
> disturbing the cloth a lot when pushing the pin through.
>
> - When installing the new pin, the point of a sharp pin will  
> sometimes snag wool fibers on the through the bushing, causing the  
> fit to become tight.  This doesn't usually happen consistently.
>
> Don Mannino
>
> ----- Original Message -----
> From: Allen Wright
> To: Pianotech List
> Sent: Wednesday, May 14, 2008 4:27 PM
> Subject: center pinning question
>
> In repinning an old (1930's) Steinway M, quite a few were loose. I  
> found that replacing the old pins with the exact same size (but  
> new) pins was producing just the amount of friction needed - and  
> even in some cases adding too much, so that I had to ream with my  
> "Mannino" burnishing files. Any theories on how that happens?  
> Something to do with the nap of the cloth changing in the process,  
> or perhaps the angle of the pin changing in the bushing, or (even  
> more unlikely) that somehow only the outer edges of the pin are  
> slightly worn on the old pins? (These are the various ideas me and  
> my colleagues were coming up with to explain the phenomenon).
>
> Thanks, and I'll take my answer off the air...   : )
>
> Respectfully,
>
> Allen Wright. RPT
>
>

Allen Wright
London, UK

http://www.broadjam.com/akwright




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