Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Why adjust aftertouch with key dip?

Probably easy question for most of you, but I need help understanding why one would ever adjust aftertouch by adjusting the key dip on a grand piano. As I understand it, key dip should be uniform. Therefore it seems one would only ever adjust aftertouch via the capstan or somewhere else. However, dip gauges exist that let you measure aftertouch at the front rail of the key, where you would ostensibly add or remove punchings to achieve the desired aftertouch.

HOWEVER, wouldn't that just mess up the perfectly uniform 13/32" key dip you just spent so much time achieving across all 88 keys? If so, and if the goal is to have uniform key dip, why would you ever adjust aftertouch with the front rail punchings?

Thanks for any insights.

Some actions might require deeper dip to allow for adequate blow, aftertouch and checking. But I consider 13/32" dip the maximum acceptable. I usually try to set 3/8" and see if the action will properly regulate there.

Deeper dip slows down the action and makes playing rapid passages more difficult because your fingers need to rise more. It can make softer playing easier. It makes glissando more problematic too.

Aftertouch is usually the last thing I set.
I made my own tool - glued a paper punching onto a strip of maple veneer so to get about .040” (I have several sizes)
Slide it under the key then put a 250 gram weight (key leads inserted into wood block) on the key and watch the the first hint of jack escapement.
Slight addition of paper punching then used to get consistent escapement the way I want it.
I find that artists notice and appreciate consistent aftertouch and the slight variations in key dip that may result) is never noticed.

Thanks guys. So if aftertouch is set at the end, meaning key dip and hammer line is already set and consistent, any adjustment to the aftertouch must necessarily alter the keydip or the hammer blow distance on that given key, since either the front punching or the capstan will need to be adjusted for that key.

Does that sound right?

I'm with Gene on this. It's very easy to feel all the elements of the key stroke when it is depressed including aftertouch, but the small differences in key dip are not felt.

Well, yeah in theory but I have never had to alter hammer line or blow distance after setting aftertouch.
Setting it as the very last adjustment means all other adjustments have been set and refined so the inconsistency that “may” result in the key dip is negligible and for the most part remains uniform.
Actions are not perfect, inconsistency happens. If any adjustment needs tweaking after setting aftertouch it is usually drop.
Also, if I’m inducing a problem that would require a hammerline or blow adjustment I do it then reset aftertouch the same way.
There is always that point of deminishing returns you got to recognize.

Also, because of the leverage, a small change in key dip with cause a large change in jack position at the end if let-off. Therefore, just adding or subtracting a thin cardboard punching is all required to adjust aftertouch.

I have to dissent a little. My hands prefer a uniform, (and not an overly deep) dip, and never notice a slightly higher hammer line to achieve proper aftertouch.

I derive the hammer blow from the aftertouch. This can sometimes leave a somewhat worn action with some hammers resting in slightly differing heights to their neighbors, but it feels better.

Thanks guys. So would it be correct to say that some prefer to keep the hammer line uniform, while others prefer keeping the key dip more uniform? Sounds like a balancing act, which I guess much of piano regulation is.

Hey Emery
I think the insight you should get from this thread is that understanding action regulation is more than developing one technique or following textbook directions.
There is more than one way to skin a cat.
For me, I have taken many classes on regulation also it’s good to know how different technicians achieve high quality results.
Also, these last 8 years I’ve worked almost exclusively for performers.
My ego has taken many hits and as a result i have learned to be adaptive.

Think about this one: I’ve not worked for Horowitz but when I listen to his recordings there is a peculiar sound or feeling that I get: it’s the impression that let-off is a hair too close, that distinctive feel/sound of the hammer striking the strings Very slightly before let-off especially when playing softer from tenor to treble. I have no idea what if any aftertouch he likes or has but My action regulation would never cut it with him.

I concur with both Ed and Gene - I've approached actions both ways. The key is to get aftertouch even, because uneven aftertouch is easily felt and affects the predictability of the note. Notes have to be predictable for the pianist to control the piano.

If you're regulating a new, fine quality Yamaha or Kawai grand piano, it may be possible to follow the specs and get a regulation with virtually perfect continuity, perhaps needing a few adjustments of .002".
Add some wear and tear, go to a piano with less accurate production quality control, go to pianos made with design and production methods that guarantee irregularity. Everything matters. The sponginess or firmness of underkey punchings will change the accuracy with which aftertouch can be felt or measured.
As we descend the ladder of reality we may make adjustments that look and measure irregular in order to produce a regulation that feels and responds as regularly as possible. Sometimes in a few minutes before curtain time and always at a price the customer can afford to pay and the technician can afford to give.