[pianotech] Brumbach Rebuild

[Paul McCloud]

Hi, Mike:
	Sounds do-able.  I did find my weights.  Most keys are at min. 58 gm up to
64+ gm downweight.  Upweight on a 65 gm downweight note is about 28gm.  So
for that note friction would be 18.5 gm.  I measured a few other keys, and
the friction was basically the same.  I made a jig using a long strip of
wood and sunk a small screw head 5 mm above the surface.  The hammer rose
33.6 mm, so I guess the ratio would be about 6.72.  I'm not sure the
accuracy of my hammer rise, but that's as best I could do.  
	Paul McCloud
	San Diego


> [Original Message]
> From: Mike Spalding <mike.spalding1 at frontier.com>
> To: <pianotech at ptg.org>
> Date: 11/01/2010 2:45:31 PM
> Subject: Re: [pianotech] Brumbach Rebuild
>
> 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.
> >