[CAUT] Hammer Alignment

[Gary Mushlin]

I used to heat the glue joint to align hammers, until I found out  
that Titebond begins to break down at about 120 degrees, and loses  
half its strength at about 150 degrees. I got this info from a  
technician named Tom Patten in his class concerning fire damage to  
pianos. My understanding is he got this information from Franklin,  
the makers of Titebond. I assume this applies to other glues as well.

Maybe this isn't enough loss of strength to affect the hammer glue  
joint significantly, but I'd rather not take the chance. I now twist  
the shank, as was described in a previous response to this question.  
If the hammer is too far off to twist the shank, I remove the hammer  
and reglue with fresh glue.

Sincerely,

Gary Mushlin, RPT


On Mar 29, 2006, at 9:16 AM, ed440 at mindspring.com wrote:

>
> I will second Wim's approach.
> I heat the glue joint with an Ace hardware heat gun on low setting,  
> moving from side to side of the hammer.  If correcting more than  
> one hammer I will move around and heat several at once.  You need  
> to give time for the heat to penetrate to the glue, and you don't  
> want to make charcoal.
> Then grasp the shank with shank knurling pliers just below the  
> hammer.  No stress on the flange pinning, and very definate control.
> Then reset the hammer sort of like setting a tuning pin, over and  
> back a few times until it's on center.
> I use Titebond in my work, but have also used this method on pianos  
> with what-ever-it-is glue. Results seem stable, but I have not made  
> a research project on the question.
>
> Ed Sutton
>
> Original message
> From: Wimblees at aol.com
> To: caut at ptg.org
> Received: 3/28/2006 2:11:50 AM
> Subject: Re: [CAUT] Hammer Alignment
>
> In a message dated 3/27/2006 11:13:17 PM Central Standard Time,  
> davidlovepianos at comcast.net writes:
> Do they always end up twisting in the same direction?  One thought  
> is that
> if you burn the shanks for straightening at the initial  
> installation and you
> hold the heat gun, say, in your right hand, you might be heating  
> one side of
> the shank more than the other which might create some unequal  
> tension in the
> shank that might play out over the period of a few weeks or months.
> I have been reading these post with interest. I seem to be getting  
> the impression that some of you are heating and bending the shank  
> to move a hammer. I personally think that might be causing the  
> problem Jon first mentioned. It has been my experience that the  
> best way to burn hammers is heat the glue joint enough to allow me  
> to twist the hammer. I then hold the hammer in its new position for  
> the glue to solidify. I have never had a hammer move after that. I  
> don't think the heat does any damage to the glue. I use Tightbond,  
> BTW.
>
> Wim

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