Let-off buttons: not enough career for correct regulation.

Posted by: pianosur

Let-off buttons: not enough career for correct regulation. - 01/06/13 01:39 AM

(This question was also posted on the Piano Forum; please check "Let-off buttons: not enough career" on that forum, to view previous post related to this. Thanks!!!).

On a grand, let-off buttons can't be adjusted for correct function. Let-off screws seems to be too long; buttons stops turning before achieving needed position.
Hammers and hammer knuckles are not too worn. Let-off button felts are not too thick. Hammers let-off now at about 10 mm from strings.
There are not independent let-off rail. Button screws are mounted on the main action rail, and buttons are "two cross holes" adjusting type.
I would like to know how could the piano come to this anomalous condition, and which is the best way to resolve the problem. I imagined re-place let-off screws deeper on action rail.
Posted by: rxd

Re: Let-off buttons: not enough career for correct regulation. - 01/06/13 03:29 AM

It sounds like a set of parts has been replaced that don't quite fit. A difference of 1-2mm in one place can give a difference of 6-7 mm elsewhere in the action. It might even be that only the set off buttons have been replaced, ( highly unlikely) which case, your intuition would be right. (the word 'obvious' disappears from the lexicon in many aspects of piano work and life in general, for that matter).

Some actions have adjustable wippen rails. Often, the screws that hold it in place can get loose and the rail could end up in the wrong position when the screws do get tightened. It is always a good idea to regulate 4-5 notes at various locations around the action first, so that minimal reworking has to be done should an anomalous situation such as this arise.

How much after touch do you have?

When the drop screws are adjusted, how much extra movement of the wippen is evident when the key bottoms out and does the action freely fit back in the case when the drop screws are adjusted? (you don't necessarily need to set the let off before settin the drop), just do a few here and there as a test.

It would help to know year, make and model. Some parts are simply not commercially available in the exact dimensions for some pianos . I remember one model where there wasn't much safety range left when let off and drop were set when it was new. This was only for a few days' production, but it can happen.

Test your intuitive feelings by replacing a few set off buttons here and there around the action, see what happens, it wouldn't hurt anything. Beware of excessive after touch which will stress the jack to breaking point.

That should be enough for now.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/06/13 12:47 PM

THe whippen rail is may be not in its original position, some rails are not secured, with time their screws may untighten. THen the knuckle is not positionned correctly letoff and drop are to be regulated (and springs) , thios can put the parts out of their normal regulation range

Reduced spread make the touch very heavy and unpleasant.

ENlarged one tend to lighten the touch but at some point you have too much friction, and the springs are not strong enough.

Normal spread depends of the action but there is a range availeable depending of the brand. between 112 and 114 on a recent Renner, but it can be more.

I would check the spread (distance between hammer and whippen center) and the lining of the knuckle in regard of the "knife mark" on the upper lever of the whippen
Posted by: Silverwood Pianos

Re: Let-off buttons: not enough career for correct regulation. - 01/06/13 01:57 PM

Originally Posted By: Kamin

I would check the spread (distance between hammer and whippen center) and the lining of the knuckle in regard of the "knife mark" on the upper lever of the whippen


For sure check the spread. Maybe the hammer set was not drilled correctly too.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/06/13 11:00 PM

rxd: I don't think someone replace let-off buttons, though I think -right now- that working on that items is the simplest solution.
I agree on regulating only few notes on the beginning to see what happens. But this problem with the let-off were there on that piano before I have done nothing.
I will check aftertouch next time I go to work on this piano. But my feeling is that when I regulate key deep to 10mm, aftertouch was almost completely missed. Have I to increase key deep to 10,5 or 11mm in this case?
I will look for more info about this piano and share it here in this great forum (and wonderful web site).
Suposed I will work on let off wires (screws), what is the best choice? I imagined take those screws out, make some milimeters deeper the original holes, and re-place the screws.
(Buttons are similar to common upright's capstains, with two perpendicular holes for inserting regulation tool.

THANKS to you and the others!!!
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/06/13 11:19 PM

Thank you Karmin!
I will check "spread" the sooner I can, and return to the forum.
The "knife mark" is that indented perpendicular line on the repetition lever, isn't it? I remember that were aligned to knuckles. I will check it again.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/06/13 11:38 PM

Is there any way to know if hammers were or not correctly drilled?
Another question to all of you, wonderfull people: How can one verify if action itself is properly placed on key bed? (I refer mainly to final height of the complete action related to strings and so)
Is there any web page with info and drawings about action geometry and measures?
Thank you!
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/07/13 05:11 AM

Originally Posted By: pianosur
rxd: I don't think someone replace let-off buttons, though I think -right now- that working on that items is the simplest solution.
I agree on regulating only few notes on the beginning to see what happens. But this problem with the let-off were there on that piano before I have done nothing.
I will check aftertouch next time I go to work on this piano. But my feeling is that when I regulate key deep to 10mm, aftertouch was almost completely missed. Have I to increase key deep to 10,5 or 11mm in this case?
I will look for more info about this piano and share it here in this great forum (and wonderful web site).
Suposed I will work on let off wires (screws), what is the best choice? I imagined take those screws out, make some milimeters deeper the original holes, and re-place the screws.
(Buttons are similar to common upright's capstains, with two perpendicular holes for inserting regulation tool.

THANKS to you and the others!!!


Possible enlarged spread, asking for more key dip

Possible knuckle farther than originally, making action ratio too low.
Just mount modern hammer/shank on an old Steinway and the letoff buttons will be too short, for instance...

checking hammer bore by the hammer center vs the strings height is enough, even in the ballpark, a few mm more or less should be accepted. but everything is adding, hammer size, spread, key ratio, stack position on the keys, etc.. if you align small mistakes on differnt parameters you can finish with the problem you mention.

knuckle and flange screw <> shank center <>knuckle location are indeed the most sensitive point, where the ratio is high little differences are making large changes.

You did tell what brnd of piano it is ? you talk of a 10 mm letoff I suppose it is a typo.

The knife mark is not showing "absolutely" the good position for the jack, more something with the whippen geometry. correct lining imply the hammer travel distance to be OK, jack lining correctly with knuckle, final jack position will vary depending of other parameters but spread alone is a good indication, as the position of the capstan on the whippen.

If the spread have enlarged, chances are that the jack have no space before touching tits stop felt
Posted by: James Carney

Re: Let-off buttons: not enough career for correct regulation. - 01/07/13 06:55 AM

Hi Pianosur,

Sounds like you haven't made the correct diagnosis - changing the position of the letoff buttons will most likely not solve the issue and will likely create more problems. An exception would be if the letoff rail itself has changed position due to loose screws or a previous tech's mistake. That could certainly cause the symptom you are describing.

Everyone keeps asking you some very simple questions that remain unanswered: What is the make and model of the piano? The serial # and year built? What work has been done in the past?

I would also suspect replacement hammers that were bored incorrectly, and/or that the replacement shanks have a knuckle center to flange centerpin distance that differs from the originals. These are only guesses though, and assume a normal regulation setup of 45mm (+ or -) hammer blow, 10mm (+ or -) keydip.

Check the hammer bore, knuckle center to shank flange center pin distance, and the action spread. (distance of wippen centerpin to hammershank centerpin). If you don't know what this means you (and the client) are probably better off referring this job to someone with more experience.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/07/13 02:10 PM

Hello James and Karmin. Please be patience with me!! That piano isn't close to were I live. The sooner posible I will answer all your questions about brand, model, spread, knuckle distance, etc.
Also it take me lot of time to translate from english, plus some unknown technical terminology!!!
THANKS!!!!!!!!
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 12:34 AM

What I say is that because of this anomalous condition, I coudn´t regulate let off distance to less than about 10 or even 15 mm (from hammer tip to string) even though I drive some let-off buttons some milimeters further than its normal limits. (also, I crashed one of them...)
Can you please explain me this sentence?:
"checking hammer bore by the hammer center vs the strings height is enough" Does "Hammer center" refers to hammer shank center pin?
Tomorrow I´ll go to take photos and measures on the piano, and look out its model, year of production and so on.
Continued...
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 01:46 AM

Hi james! Now, with more time to read, to think and to answer you...
On this piano there is no special let-off rail. See on my first post.
Can you please tell me how I check "hammer bore"? what must I measure?
I appreciate all your advices. But believe me: there is not "someone with more experience" hundreds of kilometers around where we live.(Have you ever heard about Patagonia Argentina...?)
That is the main reason why I am becaming piano technician!!
And I immensely thanks you for help me on this adventure.
Sometimes piano owners tell me: "time ago cames some renowned pro and did some key regulations...".Then I take off some keys and see those paper punchings piled up ABOVE the cloth punchings...!
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 01:50 AM

Hammer bore is the distance from the center of the shank to the tip of the hammer.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 05:20 AM

More or less..
Posted by: James Carney

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 09:42 AM

Be sure that all the flange screws are tight, including wippen flange screws. Check to ensure that all the action rail screws are tight, as well as keyframe screws (some makes, especially older pianos, require you to remove the keys for access.) Check the tightness of the stack screws to the keyframe as well. If any of the holes are stripped out (not uncommon) this can easily alter the geometry.

Another possibility is incorrect jack position, and/or repetition levers are set too high (introducing lost motion) so check that too.

Buena suerte!
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 01:50 PM

Hello James!!
Right now I am taking measures on the piano. Brand is H.Kriebel,Berlin. 686559 is the number writed on front of hammer rail. Year???
What does "stack" means?
Related to jack position, repetition lever,s height, and so on, I forgot to tell you that I have carefully done all those regulations according to Reblitz book. Until I arrive to those buttons...
Also, I suposse I have to say that this piano is a "baby grand"; not really a "grand". Here we call them "1/4 cola".
Later I will post the results of all my measurements.
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 03:36 PM

The "stack" is part of the action above the keys, with the wippens, hammers and shanks, and the rails and frame ends to hold them. H. Kriebel made pianos from 1863 to 1934. The number on the hammer rail is probably just for the action, not the piano, so I cannot give you an estimate of the age of the piano.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 05:07 PM

Originally Posted By: James Carney
Be sure that all the flange screws are tight, including wippen flange screws. Check to ensure that all the action rail screws are tight, as well as keyframe screws (some makes, especially older pianos, require you to remove the keys for access.) Check the tightness of the stack screws to the keyframe as well. If any of the holes are stripped out (not uncommon) this can easily alter the geometry.

Another possibility is incorrect jack position, and/or repetition levers are set too high (introducing lost motion) so check that too.

James, on a grand, a too high lever does not induce lost motion , it mostly change the timing of the drop and helps the jack to go back easier, but the springs are compressed during the upward motion, the knucle rest on the jack (and on the lever)

Buena suerte!
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 11:35 PM

I thought all those parts were called "action". Do you say action is "stack" plus keyboard?
Were must I look for the serial number?
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/08/13 11:43 PM

The entire action is the keyboard, stack, and damper mechanism. The stack could be called the upper action, also. There are a lot of different terms that people will use.

The serial number is usually stamped on the plate, or embossed into the wood, perhaps on the soundboard. It could be on other parts of the piano, also.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 09:03 AM

Hello friends!
Here is all I have recovered:

Maker: H. Kriebel, Berlin
Action maker: Lexon, Berlin

Hammer bore (from bass to treble):
First section: 49 to 47mm
Second section : 41mm
Third section: 41 to 42mm
Fourth section: 42 to 45mm

Knuckles:
Height: 9,5/10mm
Distance to center pin: 18mm
Distance to hammer head: 112mm

Key ratio:
From top of key front to balance rail: 225mm
From balance rail to capstan tip: 115mm

Spread: 112/113mm

Look at the pictures.
Drop screws are also out of range. And is imposible to adjust drop to 3mm from string, for example. Repetition lever hits against hammer flange!! Aftertouch? Nothing! t
Remember: I adjusted key dip to 10mm and hammer blow to 45mm
I begin to think that complete action is to much far from strings...

Enjoy this piano-puzzle!!! THANKS to all you!!!

PD: I couldn´t upload the photos. And I do read FAQ seccion. I´ll try later.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 09:41 AM

Knuckle is far from center pin, often goes with large spreads as 114 115 mm even 116 (Förster grands, with their 18mm knucke to center dimension, can have 11 mm key dip and 116 mm spread)

The pics should say what is going on better

Very short hammer bore, do you have the string's plane height ? hammer bore is of no value without hammer center height and string's height, they are by evidence very short (45 mm is YET a short bore)

Actions with so short bore should work fine , assuming it is coherent with hammer center height and string's height.

18 mm from the center is really rare, you may need 10,5 mm key dip, have a look at the sharps to white relation, at 10 mm, if your sharps are too high when they are at full dip you can believe that the keyboard need more key dip.

You have a relatively small Key ratio, at 1.95 (but accepteable) 2.03 is considered good for Renner action (why 0,03 ?)

there are mismatched parts somewhere. how did you install the jack to knuckle line ?

change the 16mm shanks on Steinways an you will need thicker letoff buttons

Reblitz cannot help on grand regulation, not really...
Posted by: rxd

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 01:58 PM

On some old pianos, the action brackets are made of an alloy that changes dimensions. This could be the case or the brackets may have been replaced with the wrong size.

An experienced tech would cast an experienced eye over the action and look for new parts and go through a process of elimination. An example being, do the ends of the keys lift the dampers at a reasonably appropriate time? Initial contact at around 1/3 key travel. Does any part look newer? Tell tale signs are, the color of the wood and metal parts, different looking glue joints at the hammers and the trimming of the hammer shank behind the hammer.

If the hammers have not been shaped, you will see the string marks more towards the back of the centre of the tip of the hammer if the hamers are bored too short. This would also happen if the hammers are excessively worn.

How do the notes at the extremes of the action regulate?, there is often far less wear there.

You will most likely find a pencil line on the side of a hammer core at the end of a section that is on centre going through the core tip and extending to the strike point on the felt. Itf not, draw one or imagine oneThis should form a right angle to the strings when the hammer touches the strings unless the original hammers were raked and have been replaced with standard stock. .

I could go on like this for ever. Time for someone else to take over.
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 02:06 PM

The hammer bore varies a lot, which would indicate that the hammers have worn and were filed unevenly. Usually there are only two bore lengths on a cross-strung, for the bass notes and for the treble notes.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 02:16 PM

sorry but no again , all depends but on most well build old grands the bore follows the string "plane (which is all but plane most often, plus jumps at the break between agrafes and capodastro...)

differences as large a 5-6 mm can be find, but most offten it is in the 2-3 mm range.

other brands consider that the action will accept a < 3mm difference in string height and use a medium dimension, based on the high/medium string's height.

then note 88 you can find some "undercentering", but generally as the medium hammers are bored 3 mm less than the usual distance this sort of auto correct- the higher hammers will be bored 90° then, while the medium ones are 91°

not easy to do so when boring, but it is good to be attentive to that.


good tip from RXD with the action brackets in "zamac" or soft alloy
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 03:20 PM

Here you have a link to the photos
Piano Photos
Now we have to wait some time for me to go and take more measures.
Diference between strings height and shank center pins must be somewhat equal to hammer bore, isn´t it?
Continued later. THANKS!!!
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 03:23 PM

Originally Posted By: Kamin
sorry but no again , all depends but on most well build old grands the bore follows the string "plane (which is all but plane most often, plus jumps at the break between agrafes and capodastro...)


Oh, really? Name one make of piano where the bore changes other than at the bass break!
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 03:44 PM

Nevermind BDB, many European grands (special mention to Bechstein)..

The plates where way less straight beforethen, actually Bechstein still does.

The jump between agrafes and capo is also common, of course today those parameters are more under control (particularely with vacuumed plates, on a Yamaha if you have 200 mm string's height you have them all along.

Steinway have a flexible frame and a crowned keybed, that goes in direction of correction, but I have seen some (very rare) with hammer bore tweaked (at the factory I suppose )

Generally speaking it is just considered normal setup to have the hammer shanks at the same orientation at letoff moment , and hammer centers lining. only the hammer bore allows this (plus little cheats on stack positionning)

"Tolerance" of the action is about 3mm, some sections being more sensitive to bore than others.
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 03:53 PM

Bechstein does not alter their bore distance. Neither do Bösendorfer nor Blüthner.
Posted by: Silverwood Pianos

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 06:44 PM

Had a look at the photos. In the hammer close up photo #10 it shows a lot of material has been used up off that hammer set. The strike point is missing more that 50% of the original felt material.

Proper regulation cannot be completed; you will have to leave some of the tolerances wide unless the hammer set is changed out.

Shaping this hammer set will make the measurements even wider.

I am wondering if there are shims underneath the action brackets to compensate for hammer wear....
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 07:36 PM

Bdb , I am not there to change your mind. For Bluethner I agree, not for Boesen nor Bechstein (factory sheet for a very recent grand in hand) strings height are took in consideration and that is why.

Not an absolute necessity however, just a way to deal with the plate shape.. Section by section.
Posted by: Supply

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 08:11 PM

As I understand it, Bechstein machines their V-bars as well as their agraffe section with CNC machines to ensure the string height is perfectly even everywhere. I learned this from a Bechstein rep. very recently.
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 08:55 PM

Even if it were the case that some manufacturers change the bore distance, which is expensive and wasteful, and offers no benefit, it is hardly common practice, and definitely not pertinent to this particular piano. I am trying to give basic information to someone who is struggling to get help in a remote part of the world, and I do not think that it is something that should have been brought up. It is just confusing to someone who needs help.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 09:12 PM

Originally Posted By: Kamin


Very short hammer bore, do you have the string's plane height ? hammer bore is of no value without hammer center height and string's height...

...have a look at the sharps to white relation, at 10 mm, if your sharps are too high when they are at full dip you can believe that the keyboard need more key dip.

...how did you install the jack to knuckle line ?


What is the most practical way to measure string plane heigth and hammer center pin heigth?

How much is too high for the sharps at full dip? I remember about 1 or 2 mm over white tops.

I aligned rear face of jacks, with tip and wood core of knuckles.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 09:47 PM

Originally Posted By: rxd

...do the ends of the keys lift the dampers at a reasonably appropriate time? Initial contact at around 1/3 key travel.

...How do the notes at the extremes of the action regulate?

...This should form a right angle to the strings when the hammer touches the strings...

...unless the original hammers were raked and have been replaced with standard stock.


First sentence: this is also related to individual damper lever adjustment, isn't it?

Second: Right now I can't tell you. Sorry.

Third: I will look for this next time I see the piano.

Fourth: Surely hammers were replaced. I saw some carelessness at the joint with shanks.

Thank you, rxd!

Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 10:09 PM

They look like original hammers. They have probably been filed once or twice, and have worn a lot since then. This would explain why the hammers are longer at the top and bottom notes, and shorter in between, where most of the wear would have taken place. I would not be surprised if the piano is at least 100 years old. Some of the hammers may have come loose and were reglued, and that may not be as neat as a new installation would be.

I think you need to take Dan Silverwood's advice to heart: Unless the hammers are replaced, and they would undoubtedly have to be bored much longer than the existing hammers, this action is not going to regulate properly.

There are things that you might do that could ease the problem, but you should not do anything that will cause problems if the owner might get new hammers later. But the safest bet would be to regulate the piano so that the let-off of all of the hammers are the same as the hammer that has the greatest let-off, and adjust the drop accordingly.

I would recommend starting with the keyboard, and setting the key dip over the front rail pin to 10mm, and the sharps 12 mm above the white keys measured at the same point. Set the let-off as described, set the drop 1.5-2.0 mm below that, and see how the backchecks work the best.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 10:21 PM

Originally Posted By: Silverwood

Had a look at the photos. In the hammer close up photo #10 it shows a lot of material has been used up off that hammer set. The strike point is missing more that 50% of the original felt material.

Proper regulation cannot be completed; you will have to leave some of the tolerances wide unless the hammer set is changed out.

Shaping this hammer set will make the measurements even wider.

I am wondering if there are shims underneath the action brackets to compensate for hammer wear....


Hello Silverwood!
Is this always so? When one have hammer felts 50% used, is no more posible normal regulation?
Which tolerances are you refering to?

Actually, action brackets are INSERTED in the key frame. I can't realize if this is original or not. What do you mean it would happen if there were shims under the action brackets?
One of the photos shows the distance between action top and pin block. Does it looks ok?
Do you think I can inprove global regulation making some changes on bracket support heigth on that piano?

Thanks!!
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 11:11 PM

Originally Posted By: BDB
They look like original hammers...Some of the hammers may have come loose and were reglued, and that may not be as neat as a new installation would be.

...I think you need to take Dan Silverwood's advice to heart: Unless the hammers are replaced, and they would undoubtedly have to be bored much longer than the existing hammers, this action is not going to regulate properly.
key dip over the front rail pin to 10mm, and the sharps 12 mm above the white keys measured at the same point. Set the let-off as described, set the drop 1.5-2.0 mm below that, and see how the backchecks work the best.

Well, I saw same empty space between hammer hole and shank end, revealing that the shank was rudely sanded before gluing. That"s why I think are not original.
Changing hammers is like an odyssey to me! Starting on how to acquire them, how to do trans-national payment, and so on...Not imposible, but...Also, I am sure the owner don't want going so far. What she is actually asking for, is good repetition. Do you think we can get it, doing regulations as you described? What about hammer stroke? 45mm or more?
Do you say 10mm key dip over front pin line, instead of over key front line?
And about sharps, I don't understand what you mean. Excuse me!!
THANKS!!!!
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/09/13 11:26 PM

You are not going to get the best repetition possible, but you should be able to get it fairly even.

The hammer blow distance should be set so that you have an aftertouch about the thickness of a coin. With the let-off set low, it may have to be set with a bit more aftertouch than ideal.

Over the front rail pin is one place key dip is measured. The key front is another, but it does not translate well to sharps, while the front rail pin works for both. The difference is small. You could adjust for it if you like, by reducing the dip a bit, say, half a millimeter.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 08:34 AM

Originally Posted By: Supply
As I understand it, Bechstein machines their V-bars as well as their agraffe section with CNC machines to ensure the string height is perfectly even everywhere. I learned this from a Bechstein rep. very recently.


Hello sorry for the OP, they certainly do the difference in height is small, and hammer bore adjusted to the half mm level, then backchecks height as well - anyway that was the case in 2011.

Due to grey iron casting they probably cannot obtain more than a certain level. Possibly it is also simply left because of the soundboard shape.

Pianosur I did not see the pics yet but the strings height at each section is necessary, as the hammer scenter height note 1 and 88 (taken from the keybed, so the action on a flat bench, or by measuring all single heights and adding them)

10 mm is a standard dimension for modern pianos, yours can have 11 mm key dip but you may be able to discover that by yourself by deduction with keys level, mortise position vs the front pin (and balance pin) level of the keys with 10 or 11 mm dip (to be checked with a small bubble jauge)



Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 08:46 AM

Originally Posted By: pianosur
Originally Posted By: Kamin


Very short hammer bore, do you have the string's plane height ? hammer bore is of no value without hammer center height and string's height...

...have a look at the sharps to white relation, at 10 mm, if your sharps are too high when they are at full dip you can believe that the keyboard need more key dip.

...how did you install the jack to knuckle line ?


What is the most practical way to measure string plane heigth and hammer center pin heigth?

How much is too high for the sharps at full dip? I remember about 1 or 2 mm over white tops.

I aligned rear face of jacks, with tip and wood core of knuckles.


The most precise way is to make small sticks with differnt lenghts (200-205 mm for basses , 196 to 200 for mediums and treble, but on old pianos string's height is often very tall as 205 to 215 in the mediums/treble.

A simpler way is to use those rules ('STanley, may be other brands) with a window :


It is important to measure at the good strike point , for instance around 45 mm from the agrafe for note 49 (A440) 2 mm form the capo for note 88, find a spot in front of the hammer center for note 1 but if they are worn or have been much filed you may want to make a small square with apiece of cardboard to evaluate where the hammer was touchin,g the strings originally .

(You also can measure the string's lenght", knowing the strike will be between 1/7 and 1/9 and that it is oftern at 1/8 lenght of the string )

WIth string's height less hammer center height you know the hammer bore more or less.

With string height less the height of the "ceiling" under the pin-block, you will know if the action allows for 47 mm hammer travel.

I will look at the pics now...

How are the whippen centering on the key capstan ? (in both directions, lateral and against the center of the whippen heel)

if the spread have compressed much the whippens will be toward the side of the most angled key (not well centered)


Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 09:07 AM

At first sight on the pics your spread is compressed , may be 1 or 2 mm. looks like the Schwander actions (while it may be another brand as "Union")as they where installed on, older Bechstein.

Are you sure the knuckle is 18 mm from the center ?

1 mmp spread more will yet do much, look at the edge of the whippen near the hammer rail, look at the position of the drop screw on the leather, probably you will see the drop screw imprint is a little moved from original.

ALso the jack end (tender ?) may be well centered under the letoff button.

Those are small hammers , small and light. not expensive hammers (tails/moldings Bechstein style ).

Anyway, with 18 mm dimension and larger spread, you will need more key dip unless you raise the hammers shanks (the touch will not be better then even if you will access to better repetition)

On those actions the whippen rail does not seem to be locked, when the screws untighten and the piano is played, the whippen rail move toward the pianist, and the touch get heavy.

The sharps may be above the white keys 2-3 mm when at full dip, but you may first test with 10.5 or 11 mm key dip on one key, regulate the sharp dip to have the same aftertouch and only now look at the sharp's height af full dip.

P.S. my mention of 11 mm key dip goes along with your 18 mm knuckle to center dimension, on a piano action, when one dimension is enlarged all the others follows.

The hammers are may be original, they could be in fact.

Good luck


PS I am may be wrong with the "spread" (or it is just 1 mm compressed) but the balance pins look a little too high in the mortise, your keyboard is possibly too low. may be just the aftertouch you miss
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 09:14 AM

original hammer bore was 45 or 46 and 50 51 (plus or less eventual corrections if the string's plane is much crowned.

Very good dimensions

Looks like hammers where normally bored and have just wear.
Posted by: Silverwood Pianos

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 09:34 AM

Originally Posted By: pianosur

Hello Silverwood!
Is this always so? When one have hammer felts 50% used, is no more possible normal regulation?
Which tolerances are you referring to?


Well,
This started when the let-off could not be regulated properly. When a hammer set has a lot of wear some of the measurements will not come up as they should. With a worn hammer set the let-off will be wide along with drop screw distance.

It seems that the let-off buttons have been adjusted all the way out and the let-off is still too wide. If you measure the amount of felt gone from the hammer set at the strike point, I bet this is the same amount of the let off being too wide……

Measure the felt at the side of one hammer, like the close up of that hammer in photo#10. Then measure the amount of felt from the front of the hammer to the wooden molding. If the front of the hammer had the same amount of felt as the side of the hammer then your let-off would be no problem…..

One way to solve some of the problems there would be to raise the key height a little bit. This will give you more key dip. But still your let-off will still be wider than normal.

Originally Posted By: pianosur

One of the photos shows the distance between action top and pin block. Does it looks ok?


The distance between the action and the pin block looks ok.

Originally Posted By: pianosur

Do you think I can improve global regulation making some changes on bracket support height on that piano?


I was just thinking about the action stack…..Sometimes when shims are placed underneath the action stack this creates regulation problems with some of the measurements (tolerances). If the stack is inserted into the key frame then leave it there.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 09:40 AM

Hi Dan, I understood the opposite (no way to obtain letoff) ofcourse you are right if this is the other way, letoff may be regulated at the original shank's heigh more or less hence 4 mm from strings for instance (but the drop screw problem show something else IMHO
Posted by: Silverwood Pianos

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 10:06 AM



Hi Isaac,
I had to go back and read the original posting. I wasn’t sure but when I saw the condition of the hammer set, I went to the other thread on the main forum and found this…

Originally Posted By: pianosur
I am sure that if let-off buttons were shorter, problem would be solved. I have almost no doubt about this.


The OP has another thread in the main forum about the same thing.

Another thread


With the hammer set in that condition the regulation will be variable especially the drop and let-off.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 10:42 AM

Well I will look at that later ...

Drop and letoff as you say depend of hammer wear, but when the whippen rail is not secured it happens it moves ,sometime one side only. Then a 1 mm difference in spread make trouble with springs and regulation.

That said it is not uncommon to have 1 mm difference in spread between basses and treble.

The action stak looks really classical schwander type. I suspect the knucke to center to be 17, visually and because it is 95% of the cases on European grands . Only Foerster used 18 mm , may be some Bluethner also. Alwys with enlarged key dip...
Posted by: Silverwood Pianos

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 11:07 AM

The whippen rail could have moved from original position. Have a look at the whippen in the first and second photos. The first is the lowest whippen and the second is the highest whippen. The drop screw seems forward on the highest whippen, but that could be the camera angle too.

The capstan seems in the correct place in both photos…..

You could be right looking at the photos of the last bass hammer and the top treble hammer. The bass shank is not quite level but this could also be from the hammer through let off and then caught by the back check while the top hammer did not go through the same thing.

I am thinking if he increases key height on those balance rail pins like you mentioned earlier, then that would increase key dip.

The Förster setup can be a little tricky the first couple of times. It looks like it could be 18mm as the hammer flanges are quite long. Most likely 17 as you mention.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 12:20 PM

Hi I was thinking of exactly the opposite situation with hammers blocking on strings, but my reasoning about spread is normal both ways.

I see the piano had 60mm hammer travel and 13 mm key dip, so it may be better now, but 13 mm ? the key frame is may be warped a lot. How where the sharps at full dip ? did they plunge under the white keys ?

Letoff can be left at 6 mm from strings due to the hammer wear for instance, as the higher you have to put the drop screw the most they are prone to touch the pinblock

At last the first and last notes should be regulated normally, but :

BEFORE any of those operations, I would take the stack out of the key frame, take all keys out, (clean the pins, lube, etc)

Then verify how the key frame is adjusted on the key bed

This have to be done with the stack screwed but without the keys .

(On those stacks if the front screw are not vertical they have to be screwed last).

It is very important to have a good contact under the balance rail (and front rail, and back rail but at last balance rail, so a paper sheet can lick under the balance rail at differnt places, then when the keys will be installed the regulation will be stable and without energy loss or "hard spots")

Many times we find the key frame warped high so no good contact (those pianos have no regulating glide bolts under the keyframe generally, if too much twisted, and hardened by time, a few judicious saw line can help to obtain a good contact.)

ONce you are sure of the spread (measure it ALSO in the middle of the action, at the beginning of all sections.

Yes the whippen looks in place when seen from the side, but this is not always centered on the capstan, there is quiet a margin, simply extreme positions may cause problems with the sharps, that raise more than the white keys generally.

in the treble, the spread looks a tad reduced, as in one pictture where the knuckles seem to be far on the whippen upper lever. Basically also the jack may center more or less under its button, that can help to understand if something have moved too.

You could raise the front rail or even raise the stack, but try to avoid creating friction and less acceleration between keyboard and action stack, so I would regulate with 5 6 or even 8 mm letoff as long as the touch is good .

The hammers are shot, visibly ; too much wear. They can be arranged but the tone will be limited the knuckles also are not in shape anymore so they produce certainly an "all or nothing" sensation .


Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 12:25 PM

The bigger problem that one can run into raising the action stack is that the drop screws will no longer fit under the pinblock. That is why I did not mention it.

It might be possible to get a bit less let-off by moving the wippen rail back a bit. But any adjustment like that can lead to other problems.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 12:38 PM

It is very easy to see if the hammers where bored at different lenghts in differnt sections : measure the tails.

To me they are bored correctly, but too much worn.
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 12:39 PM

The tails have nothing to do with the bore distance.
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 01:00 PM

Originally Posted By: BDB
The tails have nothing to do with the bore distance.


But please BDB I am not arguing , the tails show the amount of bore left on the other side, all hammers being theorically the same lenght) this is just another check added ...

As hammers seem to be replaced (hole not full with the hammer shank) they are probably too small, and also possibly originally the rake was different (I have seen 94° rake on an old Bechstein for instance, due to an enormous overcentering, itself due to an enormous amount of crowning at the plate level.

Hopefully this is not so large generally, but most European hammers ar raked 91° (in the mediums, going toward 90 or less in the high treble)

it is less expensive to use hammers bored "standard" and all the same lenght, all depend if you have a high priority with jack to knuckle relation at letoff or no.

Bechstein 2.20 string height : 203.5 -204.5 // 195 195 195 194 194.5 194.5
hammer bore 53.5 54.5 //44.5 45 45 45 44 44.5 44.5
backchecks following with 64 to 66 height depending of the hammers

So visibly the plates are precise

On older models the diffence in height between note 88 and mediums is 3-4 mm often...

Too much overblow is a real problem then as the core of the knuckle bend with time, due to the force of the jack applied too much on the side of the knuckle.

I agree this is too much nitpicking for someone asking simple answers.


Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/10/13 11:59 PM

Originally Posted By: Kamin

10 mm is a standard dimension for modern pianos, yours can have 11 mm key dip but you may be able to discover that by yourself by deduction with keys level, mortise position vs the front pin (and balance pin) level of the keys with 10 or 11 mm dip (to be checked with a small bubble jauge)

If this is a way to know the original key dip, I am full interested. What do "mortise" mean? (key button??) Can you explain me what must I check with that jauge?
Quote:
With string height less the height of the "ceiling" under the pin-block, you will know if the action allows for 47 mm hammer travel.

This piano allows for 45mm.
Quote:
How are the whippen centering on the key capstan ? (in both directions, lateral and against the center of the whippen heel)

Lateral looks OK, as you can see on pics.
I will check the second next time.
Quote:
Are you sure the knuckle is 18 mm from the center ?

Yes. But I'll measure again!!
Quote:
Anyway, with 18 mm dimension and larger spread, you will need more key dip unless you raise the hammers shanks (the touch will not be better then even if you will access to better repetition)

What does "raising the hammer shanks" means?
Quote:
The sharps may be above the white keys 2-3 mm when at full dip, but you may first test with 10.5 or 11 mm key dip on one key, regulate the sharp dip to have the same aftertouch and only now look at the sharp's height af full dip.

O.K. I am learning a lot!!!
Quote:
PS I am may be wrong with the "spread" (or it is just 1 mm compressed) but the balance pins look a little too high in the mortise, your keyboard is possibly too low. may be just the aftertouch you miss

But, I understand that aftertouch is related to key dip, not to key height at balance rail.
On this piano, balance rail (and the complete key frame)has no adjusting parts. Looks somewhat monolitic. And the balance rail is actually high. I had to put some cardboard below back rail cloth, because white key fronts had about 3mm more than standard heigth related to key slip. Also I had to add more than 2mm cardboard punchings on front pins to reduce the 13mm key dip to some normal dip.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/11/13 12:34 AM

Originally Posted By: Silverwood Pianos


It seems that the let-off buttons have been adjusted all the way out and the let-off is still too wide. If you measure the amount of felt gone from the hammer set at the strike point, I bet this is the same amount of the let off being too wide……

Then I ask: Are all the action's adjustable parts there for compensate "normal" worn hammers, compressed felts, etc, or not?

Quote:
One way to solve some of the problems there would be to raise the key height a little bit. This will give you more key dip. But still your let-off will still be wider than normal.

I think I don't need to raise the keys; simply removing cardboard punchings from front pins would be enough to enlarge key dip. Am I right?
Quote:
I am thinking if he increases key height on those balance rail pins like you mentioned earlier, then that would increase key dip.

Just the opposite!!!

Originally Posted By: Karmin
I see the piano had 60mm hammer travel and 13 mm key dip, so it may be better now, but 13 mm ? the key frame is may be warped a lot. How where the sharps at full dip ? did they plunge under the white keys ?

Key frame looks fine. The sharps didn't plunge. Perhaps they had some extra cardboard punchings on front rail pins. I don't remember now!!
Quote:
Letoff can be left at 6 mm from strings due to the hammer wear for instance, as the higher you have to put the drop screw the most they are prone to touch the pinblock

There are lot of space between fully raised drops screws and pin block!!!

THANKS TO ALL OF YOU!!! Continued...
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/11/13 11:58 PM

I was thinking and imagining one possibilitie I would like to share: What about covering knuckles with some thin leadher, to raise hammer tips to the adecuate heigth, without raising whippens out of range?

Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/28/13 11:52 PM

Hello!
I saw that the wippen flanges rail can be displaced several milimeters. Now, question is: how much?
Soon I will post more new info.
Thank you!
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 01/29/13 02:25 AM

HELLO I dont understand well : many posters told you about the possibility it had moved from original.
Also If the shanks have really knuckle at 18 they ask for more spread than 112 113 generally. The first answer stated that, in fact.

Please let us know what you finally did. Best regards
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 01/31/13 10:10 PM

Thank you Olek!
You are right. My last question were answered before!! So, I will try moving wippens rail one or two mm to enlarge spread, and to see what happens.
Now I will give you the results of my last visit to the piano (answering some questions you and others ask me time ago):

Strings to key bed:
Bass section: 211mm to 217mm (left to right)
Medium-treble section: 215mm to 212mm (L to R)

Hammer center pin to key bed:
Bass end: 162,5mm
Treble end: 160,5mm

Distance from pinblock to key bed: 174mm to 171mm (L to R)

Keys start moving dampers at 2 to 5mm from rest position.

Hammer to string angle, when hammer touches string: more than 90 degrees (hammer shank overcomes horizontal position)

Capstain centered to wippen: OK, both axis.

Drop screws old (or original) position signals. Not easy visible (perhaps, equal that current)

Spread, measured at middle of action: 113mm

Key frame warpped? No; it looks plane.

Serial Number: 22241

That's all! Keep in contact. The sooner posible I will go and I will try enlarging spread, key deep, and so on. (unless you propose to do another thing...)

Thanks a lot!
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 02/01/13 05:37 AM

SO your hammers are really to short, also, they could be 50mm to 48 mm which are common dimensions on those style of pianos (and even some modern ones).

Are the heads 90° or 91° 92°or more ?

If the piano is worth it I would change the hammers.
Actually they are not impacting the strings correctly,nor on the best place probably.

I would change them.

If nothing possible of the sort, I would try to gain a little on the keyboard side, raising the back cloth and the balance (new damper regulation necessary) so to allow me to raise also the stack a few mm.
Depending of the hammer stroke you can also raise the hammer rail (change the distance between the centers in the vertical plane, it is admitted for 1-3 mm maximum, and not ideal for touch but possible, on a Flemming action).

Backchecks could be a little too low then but they are tall on those kind of action. You will have to change the backcheck angles if this solution works.

Be ready to regulate letoff/drop springs hammer stroke and jack position . samples are necessary.

With too short hammers the letoff is elusive anyway, the easiest way is to raise the front of the stack and it goe sin the good direction in regard of the hammer stroke.

Action must be pushed in the cavity for the strike line, if 5 mm miss on the hammer, the strike is moved a lot. older hammers are not shaped totally symmetrical for that reason.

Please verify the center to knuckle dimension.

ALl the best






Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 02/02/13 01:16 AM

Hi Olek! Thanks a lot for your dedication!
I would like to change the hammers, but I have no idea how to get them. How much do you pay for a set of new hammers? I don't think the piano owner will like this idea...She really would like buying a new piano instead.

I will measure hammers angle nex time.
Knuckle to center pin is 18mm, measured on shank axis line, from middle of center pin, to middle point of knuckle wood core.

Now you give me lot of new ideas. But I suppose that first I must try to enlarge spread by moving the wippen rail, is that ok?
I already raise the back cloth and balance punchings, to get standard key dimensions. Is it posible to directly raise the back of the key frame in a case like this?

Thanks!!!
(Now, I go of camping for a few days)
Posted by: Olek

Re: Let-off buttons: not enough career for correct regulation. - 02/02/13 08:43 AM

Hello, Hammers are not that expensive but if you are not used to change hammers you will be in trouble, particularly on an old piano where they where light probably.

If the jacks are well under the knuckle you probably do not need to change the spread, you will need more key dip if you do so. Changing stack height and orientation can help, but can be time consuming, very probably the touch will feel better as soon the hammers impact correctly the strings (even if it is not ideal the tone advantage may suffice to give a better sensation in the end)
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 03/02/13 11:18 PM

Hello!

I HAVE GOOD NEWS!!

Changing stack height and orientation seemed to be a very complex work to me.
So I'tried enlarging spread about 2mm, obtaining incredible results! No more problems regulating let off and hammer drop!!
Now I need to increase key deep, mainly on blacks, because there is not enough hammer travel and aftertouch. But this was also needed before changing spread.
How much aftertouch is the ideal measure?
Is there any way or any tool for home making paper punchings for keyboard regulations? (remember: I live in Patagonia Argentina...)
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 03/02/13 11:38 PM

Aftertouch should be about the thickness of a moderately thick coin. 1 to 1.5 mm.

You might be able to find punches for making the punchings. There are plier-type punches that could make the center hole which you might find at a fabric shop or hardware store. If there is a supplier for leatherworker's tools, you might find them there. You need punches about 22 and 4 mm for the front rail punchings, 12 and 3 mm for the balance rail.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 03/09/13 09:38 AM

Aftertouch: Measured at key travel?

Punchings: So, I first make the inner hole, an then I cut the external circle with scissors?

Thanks, BDB!
Posted by: BDB

Re: Let-off buttons: not enough career for correct regulation. - 03/09/13 11:06 AM

Aftertouch: Yes, you can put in a piece of cardboard about that thickness and adjust it so the hammer just lets off, and then a piece of stiff paper to make sure it no longer lets off to set it properly. If they are long narrow strips with a slot that fits around the front rail pins, you can slip them in and out while you test notes in several registers.

Punchings: You can do that. They do not need to be perfectly round, but they should not interfere with the next note even if they rotate on the pins.
Posted by: pianosur

Re: Let-off buttons: not enough career for correct regulation. - 03/10/13 11:30 PM

OK. I understand! Thanks!
Posted by: Supply

Re: Let-off buttons: not enough career for correct regulation. - 03/11/13 09:45 PM

I am a bit puzzled. From your questions, it is clear that you have a very limited knowledge and experience regulating grand pianos. I am sure I am not the only one who thought you were simply someone working on their own piano because there was no technician where you live. But gradually I get the feeling that you are the technician.
Originally Posted By: pianosur
I don't think the piano owner will like this idea...She really would like buying a new piano instead.

While I wish you luck in your endeavor, you must understand that you really need to educate yourself in the field of piano technology before you take on this kind of work on other people's instruments. I think it is a question of ethics, personally.
Posted by: Zeno Wood

Re: Let-off buttons: not enough career for correct regulation. - 03/11/13 10:31 PM

Originally Posted By: pianosur
I would like to change the hammers, but I have no idea how to get them. How much do you pay for a set of new hammers? I don't think the piano owner will like this idea...She really would like buying a new piano instead.


Here's another suggestion: if the owner wants to buy a new piano, she should buy a new piano. This one looks nice, but it's at a minimum 90 years old, and she doesn't want to go for new hammers.

Maybe you should buy the piano from her and install new hammers, learn a lot in the process, and then you'll have a piano to sell.