Regulating the Hammer Blow Distance in a Grand Piano

Adjusting Hammer Blow Distance on a Grand Piano Action (Piano Tuning and Repair)

Welcome to our Series on Piano Tuning and Repair.

The first step in the actual regulation process of a grand piano action is to adjust the hammer blow distance. This is a simple procedure to make the adjustment. This regulation adjustment works together with many other adjustments as part of the overall regulation process.

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Video Transcript:


Welcome back to the workshop of Howard Piano Industries. Here we're going to bring you another video on piano regulating. Here we've got our grand piano action in front of us and we're going to be adjusting what's called the hammer blow distance on a grand piano action which is really one of the first steps of the regulation process, the actual regulation of the action. So basically, what the hammer blow distance is, is the distance between the top of the hammer when it's at rest and the string.

So this action model that we're looking at of course, here we've got the hammer, this bar up here, that's underneath the damper felt, is representing what we would think of as the string. To measure the distance between, or measure the hammer blow distance you're going to be measuring between the top of the hammer and the bottom of the string. Typically it's going to be around a measurement of between 1 3/4 and 1 7/8 in most cases.

Obviously, you want to get to where the piano plays well, but typically and if, for a good starting point, you want to start at about 1 3/4 which is what I have, this particular action setup is right now so it's 1 3/4 from here up to the bottom of the string. Now, to make the adjustment you're going to turn the capstan down here. Now one thing you want to make sure, is this right here is representing the hammer rail, which is the rail that's underneath the hammer shanks. This, the hammer shanks shouldn't actually rest on the hammer rail cloth. There should be a small gap and we'll show you how to make the fine adjustment on that in another video, but the first thing is, you want to make sure that that's at least lower, that it's not actually pushing up on the hammer shank, from when it's at rest.

Capstan Adjustment

To make the adjustment of how high or low this hammer is when it's at rest is you're going to turn, down here is what what's called the capstan. So what you're going to do is you're going to turn it to the right, or I guess that would be counterclockwise. If you want to lower it, or say, if you want to raise it, so if we turn it to the right, as you can see, that raises the hammer, so you can see that it's going up. It's further from the hammer rest rail at this point but if you want to make it lower, obviously, you turn it to the left as you're facing from the front of the the action.

So basically that's the basics of how to adjust it, and again, this affects, one thing you want to be aware of is, that adjusting the hammer blow distance and we'll fine-tune this, and as we get into more details of the actual regulation process, the greater the hammer blow distance is, the less amount of aftertouch that you're going to have, and then the less blow distance, you're going to actually have more aftertouch. So this, you want to keep that in mind and as we get into adjusting keydip and aftertouch in another video, we're going to fine tune that, and those two things play together very closely. So just so you're aware, but that's the basics of how to adjust the blow distance on a grand piano action.