Regulating Drop on a Grand Piano's Action

Regulating Drop on a Grand Piano's Action

Sep 21, 2023

Regulating Drop on a Grand Piano Action (Piano Tuning and Repair)

Welcome to our Series on Piano Tuning and Repair.

This step in the regulation process of a grand piano action goes along with many other steps, but is closely related to adjusting the let-off.

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Video Transcript:


Welcome back to another video here from Howard Piano Industries. Today we're going to be showing you another step in the regulation process of a grand piano action which is what's called drop. We had, in a previous video, we showed what's called let-off and you want to determine and set let-off before you set drop because it's all kind of related, but just to review, let off is the point here we're looking at a grand piano action model.

Grand Piano Action Model

We'll just show you this, it's a little bit easier to see, but let-off is the distance that the hammer can move up to the string before it lets off. So on a grand piano action it's going to come up and if we do it really slowly it won't actually hit the string but it's going to drop back, and that amount that it drops right after let-off is called the drop.

So it's going to come almost all the way up and then if I get close enough, you see it drops down just a little bit and it's actually this screw right here, which is called the drop screw that's what it controls, the amount that it drops back, and we talked about let-off being about 1/16 of an inch, maybe an 1/8 of an inch depending on what your circumstances are but generally a 1/16 of an inch of let-off on a grand piano action. The drop should be about a 1/16 of an inch lower than the let-off.

So drop should be about an 1/8 of an inch below this string. So those are general things and you can fine tune that, but those are the general measurements that you want to go by. So a 1/16 of an inch for let-off, an 1/8 of an inch for drop and that's where it is.

Adjusting the Drop Screw

So now, to adjust that, I'm going to adjust this drop screw. There's different types of heads depending on what kind of a piano it is but this one requires a grand piano action screwdriver because it's got a little slotted head. Some of them, we've got actually what's called a grand drop screw regulator. It's going to have like a spade, a really small spade type head on the top and that's going to be using another grand drop screw regulator.

So, a couple different tools depending on what kind of drop screws you have, but here we're going to see that, now we can see that you're doing really slowly, it's going to drop down just a small amount. Now if I turn that down, so there, to the right so that the screw goes down further that's going to make the drop further down. Now I'm going to do this significant amount just so you can see the difference, so you can see, that's quite a bit more from a few turns of that screw.

Now if I turn it up more, and I'll take it actually, probably past where it was before see where we're at here. So that's really not dropping much at all. If I turn it up even a little bit more it really doesn't drop at all. So you want to get to that point where it drops just a small amount, again, about a 1/16 of an inch beyond the point of let-off right about there.

Pretty basic thing, again, all these different steps and the regulation process work together, but that's the way that you adjust what's called drop on a grand piano action.