Author Topic: Lost Motion Confusion  (Read 542 times)

Offline WurlieNewbie

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Lost Motion Confusion
« on: February 01, 2020, 01:36:18 PM »
Hey guys.... I know there's been a lot of posts about this (I've read them all) but I'm still flummoxed about this lost motion business.

I understand there's supposed to be a tiny little gap between the tip of the jack and the whip felt -- and that when I press gently down on a key, the hammer shouldn't go up yet.  The hammer goes up on all of my keys at the gentlest touch so I assumed I needed lost motion.  But after doing my first key (the lowest note), I noticed the actual key dropped in height after coming back up (in other words, it was no longer level with the rest of the keys).  I could level it by gently lifting it back up.  And the key itself now feels loose and wobbly compared to the others.  It's as if the capstan screw was keeping it snug against the felt at the end of the key, and upon turning the capstan, it moved it away from the felt and made it loose.

Is this what's supposed to happen?  The hammer no longer raises at the slightest touch, so I know I've correctly added lost motion, but is that in turn supposed to make the action looser?  Perhaps my action was way too tight to begin with?

Sorry for the long post but hopefully someone can enlighten me.  Thanks!

Offline pianotuner steveo

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Re: Lost Motion Confusion
« Reply #1 on: February 02, 2020, 07:32:42 AM »
No, that is not supposed to happen. You overcompensated and now there is way too much lost motion. What model is this? 140 series or 200 series?

 Let me ask this, on the keys that you have not touched yet, do they work normally or do the hammers not always return (which means the jack is getting hung up in the felt)

IF THEY WORK FINE: Leave the lost motion adjustment alone. This adjustment is either for keys that feel sloppy before you adjust it and want to tighten them up, (The sloppiness IS the lost motion) or on the other end of the spectrum, you would add lost motion ONLY on keys where the jack gets hung up in the felt causing the hammers to not return completely. The latter is VERY rare in a Wurli. (and is sometimes caused by weak jack springs)

IF THEY DO NOT WORK FINE: Describe what is happening in detail and we will go from there.
In general, the Letoff adjustment is the main adjustment that you need to be concerned with in a Wurli EP, not the lost motion. Only adjust the lost motion if absolutely necessary.

Minute adjustments of the capstans can change things quite a bit in a Wurli. Remember, the parts are all scaled down compared to acoustic pianos, yet the capstans are full sized piano parts.
« Last Edit: February 02, 2020, 04:00:23 PM by pianotuner steveo »
1960 Wurlitzer model 700 EP
1968 Gibson G101 Combo organ
1975 Rhodes Piano Bass
1979 Wurlitzer 206A EP
1980 Wurlitzer 270 Butterfly Grand
2004 Hammond XK3
2009 73A Rhodes Mark 7
2009 Korg SV-1 73
2017 Yamaha P255
2020 Kawai CA99
....and a few guitars...

Offline WurlieNewbie

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Re: Lost Motion Confusion
« Reply #2 on: February 02, 2020, 02:45:35 PM »
Thanks for the reply, Steve.  I have a 200.

Upon reading your response, I think I'm going to go ahead and leave the lost motion alone.  I already did the let-off (with your wrench in fact!) and that made a huge difference.  I think the reason I wanted to do the lost motion was because since I was already regulating the piano, why not.  And like I said, the hammers were raising at the slightest touch of the keys which I thought indicated my piano needed adjusting.  But it wasn't causing me any problems per se, the piano played fine.  And clearly, when I started messing around with the lower capstans, that only made things worse. 

So I'll abandon the lost motion and leave it to the professionals for now.  The more I restore my piano, the more I learn that it really is an art and that my amateur knowledge can only take me so far.