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Well, I suppose my subject header says it all.

Can someone who knows a technique how to adjust let-off for grand pianos accurately, efficiently and consistently, please explain to me how to go about doing this.

You can contact me privately if you like.

Thank you,

Regards,

Greetings,
I set let-off by placing the damper on the sostenuto, then from note #1 through approx 50, I set the let-off by firmly double striking the note to get the string moving its maximum excursion, and then quickly pushing the hammer through escapement. I set let-off the least amount possible below the point at which I can hear the hammer ghost on the moving string as I push it through.

Drop has to be out of the way for this to work, and you have to have some aftertouch to do it well. It is a learned technique to rapidly move through escapement without throwing the hammer off the jack, but this gives maximum control to the pianist, albeit leaving no margin of error for the mechanism.

On the higher notes, I raise the let-off until I can feel the hammer touch the string through the key, then I lower it until the feeling becomes transparent, ie, gradually increase let-off until you cannot make the hammer touch. It takes a particular type of push to maximize the blocking and I think this is best learned by letting the hammer block, then turn the let-off down, gradually, while you will feel the blocking turn into touching, then disappear. Go back and forth while pushing through let-off and you will learn to feel the string through the key. Then set it just low enough to not feel it at all.

These are the closest I ever set let-off, and they are all pianos I see a lot of. For actions that can sacrifice some sensitivity for durability, I add a mm or so.
Regards,

Thank you very much Ed.

Regards,

Once you have set let off, Andre Oorebeek's take on aftertouch / hammer striking distance may be of interest. His equivalent method for uprights worked well for me.

Thanks Ian

LaRoy Edwards makes a really nice let-off jig for adjusting let-off with the action slid out of the piano. You set a couple of samples near the end of each section and the jig lifts the hammers near the point of desired let-off. You adjust the jig so that the sample hammers barely click on the rail and then you adjust all the ones in the middle the same. It is very quick, and painless - it makes setting let-off actually fun!

laroyedwards@gmail.com is the email listed for LaRoy in the current PTG directory.

Bill Spurlock also makes a similar tool. Here is a picture

and a link: http://www.spurlocktools.com/id24.htm

Oorebeek isn't talking about let-off. He's talking about hammer blow. Blow is the distance the hammer travels from rest, to the strings, and is usually about 45-47mm. The final distance is determined by setting after touch. Let-off is the distance from the string that the hammer disengages. If you depress the key slowly, you will eventually encounter resistance with the knuckle, if you keep going, the hammer will drop (or at least it should drop) by about 1mm; the distance right before this happens is the let-off distance. A safe distance for that is 1.5mm for plain wire and 3mm for wound wire. After let-off, there should be some additional key travel (.030-.045"), and that is after touch.

For in-piano regulation, I use the Spurlock jig. Great tool!

Thanks Ryan and B986

I do like what Ed wrote and think that I will press on in that direction.

Regards,

Beethoven,

Thank you, I have edited my post to clarify.

Oorebeek's final point is about after touch. He recommends 0.4mm or .016", interestingly about 33% - 50% of what you suggest.

As we are straying OT, better leave Mark to follow Ed Foote's advice!

Oorebeek's measurement is based at the hammer. Mine is based at the front rail punching.

Well spotted. To square the circle, how much hammer movement will result from an after touch key movement of .030" - .045"?

Greetings,
After the individual setting of the let-off, I do set the dip by measuring a consistent after-touch on each individual key. Once the dip is finalized, I can set the drop and back-checks.

It is interesting that action inconsistencies show up as a difference needed in key-dip to keep after-touch the same. If the differences are too great (more than .008"), I use the blow to split the difference, ( raising the hammer has the same effect on after-touch as deepening the dip).

This is with wooden parts, which are really erratic. The last two WNG composite part actions I have built are so consistent,all the way through, that not only was the dip and after-touch nearly dead consistent, but when the action was regulated, all the let-off buttons were in a nearly perfect, straight, line. I have never seen that before.
regards,

This is interesting reading. What ever happened to the ratio of the key dip to the blow distance?

Greetings,
Not sure what is meant by "what ever happened", but the ratio is still there. The blow is often determined by the piano's construction, so there is a range. Key dip can't vary by much more than .030" from the least to the most that players will accept. Sharps can't be much more than .500" above the naturals.and if they need .400" for dip that leaves .1" for height above the keys when depressed.The blow and dip can move around within these limits to effect different feels for the pianist.
Regards,

Ryan, apart from me wanting to learn to adjust let-off according to what Ed wrote, i think i am also going to look into the Spurlock jig too. Thanks again for your input.

The Spurlock tool is a good one, but I have found LaRoy Edwards' version more convenient to use. It is a little bulkier than the Spurlock tool. So if you want a more compact tool, go with the Spurlock version.

The jigs are nice, of course, but you can use a simple slat of wood that rests on little wood or felt blocks on the hammer rest rail. Same effect - two minutes of fiddling to get it where you want it - zero cost.

Indeed. Spurlock explains this method for upright regulation.

For grands, you can also get a piece of aluminum u rail and fit a properly sized slat of wood inside the u. if you drill two holes in the wood, and put long screws in the holes, you can make a cheap version of the jig.

Thank you Ed for your great explanation. I am an autodidact and read a lot. But this was the best by far.