OK next question: Tugging on ham. rail chek lost motion

[Dean May]

I am regulating right now an old upright action with new key tops, bushings,
key pins, hammers, ecsaine on the hammer butts, etc. The hammers were
bobbling and I couldn't figure out why as there was adequate after touch.
But on some notes it didn't matter where I put the back check, it wouldn't
catch. It turned out to be multiple problems. 

 

I hadn't changed the bridle straps because they were fairly new. But the
previous tech had glued in tapes with no cork into the catcher hole. He did
it so the tape came out and was glued to the top of the hole. That position
alone caused problems with interference with the catcher and it was
compounded by the little bit of glue on the tape sticking out causing it to
be a little stiffer. This little bit of stiffness was actually pushing the
back check away. I think if the tape had come out the bottom of the hole the
problem would have gone away. But no matter. I'm redoing them all, of
course. I don't understand why anyone going to the trouble of gluing on
tapes wouldn't go ahead and glue them to the underside of the catcher dowel
instead of the hole. 

 

The second problem I spotted was on some of the notes the felt on the front
side of the jack was jamming against the felt on the back side of the bottom
of the catcher hole. That second piece of felt had been replaced, no doubt
by the previous tech, and it appears to be too large and too firm. I see no
need to have it both pieces. There is no other rail in the way for the jack
to contact. 

 

Sometimes it's not just that the beast is old and worn, but you have to
watch out for previous modifications. 

 

Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802

 

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From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Fenton Murray
Sent: Sunday, February 10, 2008 9:29 PM
To: David Nereson; Pianotech List
Subject: Re: OK next question: Tugging on ham. rail chek lost motion

 

Julia,

Some tell tail signs of lost motion are an uneven key board ,bubbling
hammers, dampers not lifting. Run your finger tips very lightly across the
keys and watch the back checks, see if they move while the hammers stay put.
Play the piano! you can fell it. It's all about correcting low performance
in the action, not just a checking and adjusting for a certain
specification. You're asking how to check for lost motion in this piano, I
would ask, why do you suspect that there is lost motion? BTW, blindly
setting hammer blow and lost motion to spec in an old, worn upright action
can have a few consequences that you might not be happy with.....like no
damper follow. You gotta compromise on the old beasts. Hang in there.

Fenton

----- Original Message ----- 

From: David Nereson <mailto:dnereson at 4dv.net>  

To: Pianotech List <mailto:pianotech at ptg.org>  

Sent: Sunday, February 10, 2008 1:45 PM

Subject: Re: OK next question: Tugging on ham. rail chek lost motion

 

You're not really checking lost motion, but, as you said in your first post,
the lack thereof.  You can depress the damper pedal (so the returning
wippens don't have any assist from damper lever springs), then depress ten
keys at a time and let them up very slowly, looking to see if any jacks
don't snap all the way under their hammer butts.  If they don't, turn the
capstan down by quarter turns until the jack returns all the way when the
key is let up slowly.  Otherwise, the visual "backcheck wink" method is as
good as any -- very lightly tap on the keys and see if the backcheck just
"winks" before the butt moves (watch the catcher).  Or, as someone else
suggested, press on the tail end of the keys, mashing them into the back
rail felt a little, and see if any hammers wink backwards.  If so, the jacks
are holding them up off the rail a little.  

    --David Nereson, RPT

----- Original Message ----- 

From: KeyKat88 at aol.com 

To: pianotech at ptg.org 

Sent: Friday, February 08, 2008 10:13 PM

Subject: OK next question: Tugging on ham. rail chek lost motion

 

Greetings,

 

      Thank you for answers validating my method of checking lost motion. 

NEXT question....Then how can I check lost motion when this one piano a
customer has, has a brace which will not allow the rail to move with a
backwards tug and I cant check the lost motion, Is there another way of
checking it? I am guessing I have to go key to key and check it.

 

THank you

Julia

Reading, PA 






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