Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Drop screw and let-off adjustment

I've been trying to understand the relationship between the drop screw adjustment and let-off adjustmnet. The drop screw is a poor terminology. It doesn't drop the hammer at all, but rather rests on the repetition arm, after escapement has occured, if properly adjusted. How do you balance a close let-off ;ie, one which is just short of blocking the hammer, with the proper drop adjustment so that the escapement is seamless and the hammer (or knuckle) is resting on the repetition lever ready for a fast trill? I'm not sure I understand my own question. In others words, the note should feel as if it is at the tip of the hammer ready to be played again. The hammer can play very very softly without the dreaded double tap and the escapement should be very contolled. This gets harder to achieve the higher up you go on the keyboard.

The hammer, after let-off, drops to the level established by the drop screw when played softly.

Well, first of all, I don't use a close let-off. It just results it too much variation in the feel of the action, and too much potential for trouble. Besides, there are pieces which direct the player to depress keys silently. A uniform 1/16" let-off provides an even, reliable touch. I use a drop of another 1/16" below the let-off, so that it is even all the way down in the bass, where if the hammer is too high, the string could hit the hammer at drop.

It is possible to set the drop higher than the let-off, but then you cannot set the let-off properly, and you cannot feel the let-off and aftertouch. The touch is very poor. One should be able to feel the let-off and the aftertouch when playing.

Do you set the let-off first and then adjust the drop screw? I do like to feel the escape, but evenly and smoothly. I know there are other adgustments that influence these adjustments, but assume everything else is where it should be.

After al the other adjustments have been made(key level,dip,blow distance),let-off can be set first if the dropscrews have been turned down enough so that there is some drop.Drop should be set to occur by observing the the jack contacting the let-off dowel at the same time that the drop screw contacts the buckskin of the repetition lever.This can be observed by viewing the action by looking down from the side.If let-off is set for 1/16",drop(or stop,because the screw is actually stopping further movement of the repetition lever) should be set for 1/16" below let-off.In other words with the action in the piano,depress the key slowly throgh let-off and drop untill it is bottomed out on the front rail punching,the hammer should be 1/8" below the string.As BDB stated,the drop and let-off in the bass section should be 1/16" or more,and drop a little more because the bigger excursion of these strings can cause the hammer to block or kick off the string during loud playing of these notes.

Curry,

That's a great explaination, thank you.

Drop screw is a terrible term. It should be called the stop repetition lever screw (SRLS).

Curry,

A little more help, please. Correct me if I'm wrong, but if the drop screw is down too tight, can it cause the perception of a heavier action or one with more friction? Will bringing that back some also allow for a faster repetition?

Ralph,if you adjust the dropscrew down too much it will engage the rep lever too soon,(before the jack engages the let-off dowel),and you won't be able to set let-off.You will also feel the tension of the rep spring as the the screw engages the rep lever.Starting from scratch,you would adjust the dropscrew a few turns so that there is some drop in order to be able to begin setting let-off.You wan't let-off and drop to be as close to the strings as possible.This will help to ensure fast repetition.That is if all other parameters are optimal,(ie.friction,balance weight,key inertia,backcheck distance,action geometry).

You need to adjust the repetition spring tension before you adjust the drop screw. You won't get a reliable indication of the drop without that. I generally set the let-off and the drop right afterwards, so I set the spring tension just before.

Thanks to both of you. The action is good, just a bit too stiff and that maybe the spring tension. Fortunatley I have Renner wippins with the spring adjustment screw. Must easier than the old Steinway technique of bend and hope.

The let-offs and drop screws are pertty well set now. That can take quite awhile to get right. There's a mid range in adjustments that you have to get to before actually fine tuning these two things.

The spring may very well be in need of adjusting because it is hard to feel the drop.