Poor key morticing

[Mike Bratcher]

Hi Ric,

You gotta' picture of that reamer?

I was afraid I was going to need to rebush the balance rails.  This was 
really the main reason for the post.  I figured I would try the list first 
for an alterative.

Thanks

Mike Bratcher
----- Original Message ----- 
From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
To: "Pianotech" <pianotech@ptg.org>
Sent: Wednesday, September 08, 2004 3:04 PM
Subject: Re: Poor key morticing


> Ah yes...
>
> The ol <<top of the balance rail hole is to tight/high>> syndrom.  Causes 
> all kinds of nasty problems.  Only one thing for it.. and that is to 
> bore/ream it out to the appropriate dimensions.
>
> There is a kind of reamer available for this job that fits universal 
> regulating handles.  And I am sure you can get a standalone hand tool too. 
> Problem is that it might be difficult to get in past the bushings.  So you 
> may end up with a rebushing job as well.
>
> You can always try and widen the holes out by some home made contrivance 
> if this is a low budjet job.  Bang to obong a balance rail pin, sharpen 
> the edges a bit and mount it in a hand tool.... etc.
>
> I run into this problem quite a bit with Petrofs and some other eastern 
> European makes.
>
> Cheers
> RicB
>
> Mike Bratcher wrote:
>
>> Yes, I am aware of how to ease a hole properly, but easing isn't the 
>> problem here.  The problem here is that when the key was manufactured 
>> they left too much wood in the top part of the balance hole.  If I were 
>> to just ease the hole, I would not be correcting the problem.  The key is 
>> "teetering" on a pin, so if the bottom of the balance rail hole is 
>> resting on the punching the top of the hole will wedge against the pin. 
>> Now the top of "that" hole needs to have clearance when the key is 
>> depressed.  When I say top of "that" hole, I don't mean the top of the 
>> key button.  I'm talking about one sixteenth to one eighth of an inch 
>> above the balance rail hole.  The wood here is about one eighth.  There 
>> needs to be clearance at the top of that hole roughly an arch, to clear 
>> the pin.  Otherwise the pin will be bending. And, yes Terry they are all 
>> tight(pins in the balance rail that is).  Normal Key easing in this area 
>> will size the hole, but it will not address the problem at the top of the 
>> hole.  My easing tool if used to try this will damage the hole and create 
>> more problems.
>>
>> Mike Bratcher
>> -
>
>
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