[pianotech] plate lags, (was persistent customer)

[Geoff Sykes]

It's so easy to get into arguments on the list. 

Screws imbedded into metal rarely need tightening unless they are subject to
vibration. And even then the phenomena is rare. That's because metal changes
very little with changes in temperature or humidity. Wood, on the other
hand, can change quite dramatically with changes in temperature and
humidity. Why do you think a piano can go out of tune simply by turning on
some stage lights? What I'm referring to is changes in humidity that cause
wood to swell and shrink. Over time, things like screws, nails etc., will be
effectively squeezed out. They get loose. They need to be tightened. As was
mentioned in an earlier post, if you tighten these screws several times a
year you do stand the chance of over tightening them and damaging the wood.
All I'm saying is that checking them every once in a while will likely keep
them tight enough to maintain a stable plate and subsequently a stable
tuning. Any more than that is overkill, and possibly not a good thing. And
as always, the key here is ymmv.

-- G


• Geoff Sykes, RPT
• 626-799-7545
• www.ivories52.com 


-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ron Nossaman
Sent: Monday, December 29, 2008 9:19 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] plate lags, (was persistent customer)



> Geoff Sykes wrote:
>> Keeping them tight all the time is not so important as making sure
>> that they are tight enough over the long haul.
>>  
>> -- G
> 
> Why?
> 
> Ron N

Ok, more to the point, by what mechanism would they get looser 
than "tightenable", and why isn't the criticality of 
tightening plate screws obvious in tuning stability unless it 
isn't in fact critical?

Ron N

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