[pianotech] Brumbach Rebuild

[Mike Spalding]

Paul,

misfired a minute ago - this time the message is complete...

I think the most straightforward error-free way to measure action ratio 
is to depress a white key by exactly 5mm, and measure how far the hammer 
rises, then divide the hammer rise by 5.  I believe it was in an 
Institute class where I was shown how to make a weighted block with a 
capstan in the bottom surface to achieve the "exactly 5mm".  The block 
is long enough to span 5 or 6 keys, and weighs enough to more than 
overcome the downweight of the one key under the capstain,  but not 
enough to dip the other keys supporting the block.  Let me know if you'd 
like a photo.

Mike

On 11/1/2010 4:01 PM, Paul McCloud wrote:
> Hi, Mike:
> 	I'll do that as soon as I can locate my weights.  What is the best method
> to measure the action ratio?
> 	Paul
>
>
>> [Original Message]
>> From: Mike Spalding<mike.spalding1 at frontier.com>
>> To:<pianotech at ptg.org>
>> Date: 11/01/2010 1:48:47 PM
>> Subject: Re: [pianotech] Brumbach Rebuild
>>
>> Paul,
>>
>> If you haven't done it already, measure the down weight, up weight, and
>> action ratio, and let us know what they are.
>>
>> thanks
>>
>> Mike
>>
>> On 11/1/2010 2:58 PM, Paul McCloud wrote:
>>> Hi, Friends:
>>>      I've got a Brumbach action that someone rebuilt some years ago.
>>> The pear shaped knuckles are now the standard type, and new hammers,
>>> shanks and whippens are fitted.  The capstans are relocated closer to
>>> the balance rail.  The customer's complaint is that some of the keys
>>> are sluggish to return.  After removing the action, I discovered that
>>> jiffy weights are mounted under the keysticks just behind the front
>>> rail.  This is in addition to the leads in the keys.  As it is, the
>>> keys play ok except for a few in the bass which is where the
>>> troublesome notes are.  What I'm seeing in the action setup is that
>>> the capstans are set too high.  The top of the capstans is above the
>>> "magic line".  If you observe the capstan/heel contact point, you can
>>> see quite a bit of sliding as you press the key.  Since I am not
>>> normally set up to rebuild actions and do all of the balancing work, I
>>> wondered if someone could ex plain how I would go about rectifying
>>> this action.  My instinct tells me that the heel should be
>>> taller/longer, and the capstan lowered so that they meet at a point on
>>> the "line".  What I don't know is if this will solve the problem or
>>> just lead me down a blind alley with more problems awaiting.  I don't
>>> have downweight/upweight measurements because I misplaced my gram
>>> weights somewhere.    I also noticed that the jack and knuckle are at
>>> a bit more of an angle than I'd like to see.  I wish I had the parts
>>> kit from Renner or Tokiwa to try some different combinations.
>>>          Interesting that this piano belonged to the late John Lennon,
>>> and he wrote "Imagine" on it.  The owner says John purchased it in New
>>> York.  I'm not sure if the work was done before John purchased it, or
>>> later.
>>>      Any suggestions or advice are much appreciated.  I do have more
>>> photos if needed.
>>>      Paul McCloud
>>>      San Diego
>>> pmc033 at earthlink.net<mailto:pmc033 at earthlink.net>
>>> EarthLink Revolves Around You.
>