Adjusting Lost Motion in a Spinet Piano

Welcome to our Series on Piano Tuning and Repair.

Adjusting lost motion is a step in the regulation process of a piano and making this adjustment on a spinet piano differs from making the adjustment on other types of vertical pianos. In this video we go through in detail how to make this adjustment.

If you want to see more of our Piano Tuning and Repair Seriesclick here to access the entire playlist.

Video Transcript:


Welcome back here to our workshop at Howard Piano Industries. We're going to be showing you today how to adjust the lost motion on a spinet piano. We had a previous video on that we made quite some time ago on adjusting the lost motion on a vertical or console or upright piano.

Spinet Piano Action Explanation

it's a little bit different on a spinet piano, the basic concept is the same but the way that you make the adjustment is a little bit different on a regular. Here we've got a spinet piano action in front of us, now as you can see the backs of the keys are stopped short to be able to go underneath the action, so the whole action is dropped down below the backs of the keys except for, of course, the hammers are above the hammer butts and the whippens and so forth.

Those are all below the level of the backs of the keys and that so they can make the piano shorter for space and it makes the piano a little bit less expensive. They used to make spinet pianos, they don't really make them anymore that I know of and haven't for a number of years but there's still a lot of spinning pianos out there. We're going to show you today how to make the adjustment done on lost motion on a spinet piano action. If you watched our previous video on adjusting lost motion on vertical piano you know that the keys that go all the way underneath the back of the action, and the back of the key pushes up on the bottom of the action part and makes the hammer go forward, and the way that you adjust that is on the back of the key.

You would take the key out, and on the back of the key, there's what's called a capstan. It's usually brass or sometimes it's wood but you turn that which raises or lowers it. To adjust how high or how low it is, which adjusts how soon or late it pushes up on the hammer butt which pushes the hammer forward. You might find our video on how a piano action works to be helpful if you're unfamiliar with some of these different terminology on how the action of a piano works. So you want to watch that if you're not familiar with that, but here we're gonna go and show you on the back of this what happens.

Closeup of Spinet Piano Action (How it Works)

We're looking from above, we've got right here the lifter grommets and that goes into a fork at the end of the key. I can push that out, you can see there's a fork there and this is just a rubber grommet that locks into the the back of the key, and then as you can see, there's a rod or a wire which is right here that goes down to what's called an elbow and that gets attached to the whippen, so by pushing down on the front of the key that balances on this balance rail pin and it makes the back of the key go up.

As I push the key in front of the key down, front of the keys going down, the back of the key is going up, and what it does is raises the lifter wire which pulls up on the whippen which raises pushes up on the jack and pushes the hammer butt up which makes the hammer go forward and strike the string. There's a little more detail in that on how the piano action works but today we're primarily going to show you how to adjust the lost motion.

What lost motion is, it is the amount of play or the amount of movement that the front of the key makes before the hammer starts moving which it should be little to no movement at all. Now you don't want it to be where the hammer is if it's what's called negative lost motion, the hammer is going to be sitting up here so that you know so that it might be up this much so that the hammer shank is not resting on the hammer rest reel.

Adjusting Rubber Grommet Process

So the way to adjust that is we're gonna just turn this rubber grommet here. Sometimes they're square, sometimes they're round rubber grommets, and then they're like a plastic nut like this one right here. I've got this one this, is from a different piano but it's got this plastic nut here, so either way you've got it, you're going to turn it, if you turn it counterclockwise it's gonna raise the raise the grommet which is going to make it so that you've got more lost motion if you need.

If you've got too much lost motion, then you need to turn it clockwise which is going to lower the grommet and actually raise the lifter wire. What I'm going to do here, this one's actually adjusted pretty good, so I'm gonna raise it here to put in lots of lost motions so we can see for an example okay so now here I'm I'm pushing on the key, and what we want to do is look at the movement of the back check which is this piece right here. That's kind of a good guide to see that's a lot of movement - okay which means the key is moving way more than it should before it starts to engage the hammer butt. I'm doing all that movement without the hammer but moving right here is the catcher and you can watch that, and you can see that the backcheck is doing all that movement without the catcher moving.

Now if I can do it a little bit further you can see the catcher starts to move, but when the key is at rest now if I go to the one right next to it, You can see it wiggling which is is about the right amount. You want it to wiggle just a little tiny bit without the hammer butt moving. If I go very far at all then I can make that hammer butt move. If you don't have any movement at all, it means you probably need to put a little bit of lost motion or a little little extra motion in that adjustment, and the other thing you can check here too is if you pull back on this hammer rest rail and watch the hammers, as I do this you can't see that in the video but I can see it.

What happens is those hammers should fall back just a little bit as you tug back, you know the hammer rest rails not going to move much because it's resting on these posts right here, but you can get it to move a little bit and if you pull back on that, and those hammers don't move at all, that means you need to put a little bit of lost motion into your keys so that's the basics.

Essential Tools

What I've got here, is I've got a combination tool handle and this is our Kimball Lost Motion Regulator which is the tool that's designed for using on these square rubber lifter grommets. If you've got this - this one's called a Baldwin Wire Finger Nut. You can turn by hand, the square rubber lifter grommets are pretty tough to turn by hand, they can be done but it's tough on the fingers. Having that Kimball Lost Motion Regulator is helpful. It's not just for Kimball pianos, I mean this is a Story & Clark piano, so it's whatever piano has the square rubber lifter grommets.

That Baldwin Wire Finger Nut which of course are not only for Baldwin pianos but they call them that. That can be adjusted with a quarter-inch drive socket, the quarter-inch driver. That's what is used to adjust that if you can't use your fingers but usually those Baldwin Finger Nuts can be adjusted by hand. Hopefully, the video has been helpful for you, it shows you how to make adjustments. Again, you want to adjust it so that you've got just a little bit of wiggle in that backcheck like this one, before the hammer butt starts moving.

Again, this is too much, okay so again we'll put that back. I can show you as we adjust that I'm going to turn it down let's see if it still needs to be adjusted more, here we go that's pretty good. I can still move the hammer, still moves when I pull back on the hammer rest reel.