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. > >
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