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#2137282 - 08/22/13 03:23 PM Changing an upright action ratio
musicbased Offline
Full Member

Registered: 09/23/12
Posts: 105
Loc: UK
Hello, would anyone be able to suggest the ways of lowering the action ratio on an upright?

I was just reading another thread, in which somebody mentioned how a large blow distance with shallow key dip will feel heavy. I do agree with this, but what else can you do if the action ratio is so high that changing either of those two will result in too much jack movement?

I know the capstan can be moved,or bending the pilots, but what are the other options?-For example, changing hammer butts,whippens etc?-Can changing centre pin heights/distances alter the ratio?-In what way?-(assuming the change is part of an action redesign).

I'm very familiar with all the changes that can be made on a grand, but not so much with uprights.

Would appreciate any thoughts!

Thanks,

Lewis.


Edited by musicbased (08/22/13 05:17 PM)
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#2137372 - 08/22/13 07:13 PM Re: Changing an upright action ratio [Re: musicbased]
Withindale Offline
2000 Post Club Member

Registered: 02/09/11
Posts: 2058
Loc: Suffolk, England
Originally Posted By: Silverwood Pianos
Shallow key dip along with hammers too far away from the strings will fell very heavy and slow.

Wouldn't correcting the regulation be better than changing the action ratio?

Do you have a particular piano in mind?
_________________________
Ian Russell
Schiedmayer & Soehne, 1925 Model 14, 55" upright
Ibach, 1922 49" upright (project piano)

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#2137377 - 08/22/13 07:30 PM Re: Changing an upright action ratio [Re: musicbased]
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5317
Loc: Olympia, Washington
Originally Posted By: musicbased
Hello, would anyone be able to suggest the ways of lowering the action ratio on an upright?

I was just reading another thread, in which somebody mentioned how a large blow distance with shallow key dip will feel heavy. I do agree with this, but what else can you do if the action ratio is so high that changing either of those two will result in too much jack movement?

I know the capstan can be moved,or bending the pilots, but what are the other options?-For example, changing hammer butts,whippens etc?-Can changing centre pin heights/distances alter the ratio?-In what way?-(assuming the change is part of an action redesign).

Aside from the capstan and/or dowel wires as you've already noted you can look at the placement of the tip of the jack relative to the hammerbutt center. This is a very short lever arm to start with and it gets shorter as the butt felt wears and/or compresses. If replacing the butt felt seems in order chose its thickness carefully.

ddf
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#2137546 - 08/23/13 05:02 AM Re: Changing an upright action ratio [Re: musicbased]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
sure !
a 0.5 mm change in cushion thickness, is yet changing the leverage a lot.

mounting too thin, or too thick cushions (or simply lesser quality ones) is the most common mistake in vertical action rebuild.

and not one that can be corrected on site.
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#2137558 - 08/23/13 05:58 AM Re: Changing an upright action ratio [Re: Withindale]
musicbased Offline
Full Member

Registered: 09/23/12
Posts: 105
Loc: UK
Originally Posted By: Withindale
Originally Posted By: Silverwood Pianos
Shallow key dip along with hammers too far away from the strings will fell very heavy and slow.

Wouldn't correcting the regulation be better than changing the action ratio?

Do you have a particular piano in mind?


Yes that was the comment i was referring to and in that thread,yes sounds like the regulating needs correcting.

However, i'm thinking about if an action regulates with excessive blow distance combined with dip under 10mm, the action ratio is too high.
It would be nice to know what options there are to reduce the action ratio with new parts during a rebuild, especially as new hammers are likely to be slightly heavier than original too.

Thanks Del and Isaac, i will experiment with that at some point. I don't tend to see much variation in cushion thickness on new parts though, have you ever had to modify new parts?

Perhaps it's not that common.
I don't actually see excessively high action ratios on uprights too often, but i have seen a few. I remember a Grotrian Steinweg in particular that was incredibly high.


Edited by musicbased (08/23/13 06:10 AM)
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#2137575 - 08/23/13 07:46 AM Re: Changing an upright action ratio [Re: musicbased]
Del Offline
5000 Post Club Member

Registered: 09/04/03
Posts: 5317
Loc: Olympia, Washington
Originally Posted By: musicbased
Thanks Del and Isaac, i will experiment with that at some point. I don't tend to see much variation in cushion thickness on new parts though, have you ever had to modify new parts?

I haven't done much vertical action work for years but, yes, I have had to modify new parts. Set up a couple of samples and see what you have. If the OAR comes out really high try a thicker butt felt. Just don't go too far -- you don't want the jack tripping on a hard blow.

Other than that you'll have to go to the capstan/wippen contact point.

It's astounding just how many vertical pianos there are with really bad action geometry.

ddf
_________________________
Delwin D Fandrich
Piano Research, Design & Manufacturing Consultant
ddfandrich@gmail.com
(To contact me privately please use this e-mail address.)

Stupidity is a rare condition, ignorance is a common choice. --Anon

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#2137578 - 08/23/13 08:04 AM Re: Changing an upright action ratio [Re: musicbased]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France

The capstan whippen is where it is the most easy, assuming you do not have a too short lever on the butt.

but you modify the half blow placement, so the touch is also changing.

Renner stacks can be bowed if necessary.
the problems I ve seen was after repairs, the jack cushion did not hold the expected thickness (or was not well sampled)

the rest position of the action can be computed with some measurements. the method is a little long , you need 9 measures, but it is interesting. the horizontal placement of the whippen is looked for at mid blow.

Renner propose 2 butts with different leverage.


Edited by Olek (08/24/13 08:14 AM)
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2137870 - 08/23/13 05:08 PM Re: Changing an upright action ratio [Re: musicbased]
Withindale Offline
2000 Post Club Member

Registered: 02/09/11
Posts: 2058
Loc: Suffolk, England
Originally Posted By: musicbased
I'm thinking about if an action regulates with excessive blow distance combined with dip under 10mm, the action ratio is too high.

As it happens the Ibach in my signature below fits your description: blow distance 49mm, dip 9.4mm, overall action ratio to let-off 5.5.

The Ibach action does not seem particularly heavy but it's certainly heavier than the Schiedmayer: overall action ratio 4.0.

The problem with that low action ratio was the key dip came out at over 11mm when I followed Reblitz. Reducing key dip to 10.5mm and restricting jack movement made the action feel much more responsive.
_________________________
Ian Russell
Schiedmayer & Soehne, 1925 Model 14, 55" upright
Ibach, 1922 49" upright (project piano)

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#2138084 - 08/24/13 03:23 AM Re: Changing an upright action ratio [Re: Withindale]
musicbased Offline
Full Member

Registered: 09/23/12
Posts: 105
Loc: UK
Originally Posted By: Withindale
Originally Posted By: musicbased
I'm thinking about if an action regulates with excessive blow distance combined with dip under 10mm, the action ratio is too high.

As it happens the Ibach in my signature below fits your description: blow distance 49mm, dip 9.4mm, overall action ratio to let-off 5.5.

The Ibach action does not seem particularly heavy but it's certainly heavier than the Schiedmayer: overall action ratio 4.0.

The problem with that low action ratio was the key dip came out at over 11mm when I followed Reblitz. Reducing key dip to 10.5mm and restricting jack movement made the action feel much more responsive.


Thats interesting. Thanks.

Has the ibach been rebuilt?-My experience is that rebuilding with new parts can push these actions into the upper limits of heaviness, but maybe thats not always the case. I don't do uprights too often.

What blow does the Schiedmayer have?-How did you restrict the jack movement?

Also, what method are you using to calculate the action ratio?-Those numbers seem quite different to mine!

(sorry for all the questions!) grin
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#2138125 - 08/24/13 06:59 AM Re: Changing an upright action ratio [Re: musicbased]
Withindale Offline
2000 Post Club Member

Registered: 02/09/11
Posts: 2058
Loc: Suffolk, England
The Ibach action and hammers look original.

The Schiedmayer's blow distance is 45 mm. It was 40 mm when I got it and it did not play well.

I restricted jack movement by adding 0.25 mm punchings to reduce key dip. When the key is depressed slowly, the dip at which the hammer falls back as the jack slips out from under the butt (let off according to Reblitz) is about 10.75 mm. I was not happy with an 11 mm key dip so, in the end, I caught the keys close to the strings and reduced key dip to 10.5 mm. Touch and repetition are good.

The method I used to arrive at action ratio was to measure key dip and hammer movement. These movements are non-linear. The ratio for the initial movement on the Schiedmayer was just over 4.5 coming down to 4.0 at let off (42.7 mm hammer movement after 10.7 mm key movement). The initial ratio for the Ibach was over 5.8.

Del wrote the following about action ratios in 2011. He was referring to grand actions but I think much of it also applies to uprights.

Originally Posted By: Del
Most modern pianos have some version of the Erard/Herz action. Most of these are patterned rather directly from the design Steinway adapted something like 150 years ago...

So…the basic action functions and geometry are more-or-less fixed. What are variable are things like hammer mass and the overall lever ratio. Years back—as in when I started out in this business—the de facto standard hammer travel was approximately 45 mm (1 ¾”) and key travel was approximately 9.5 mm (0.375”). Even then, of course, Steinway was a bit different with a published standard key travel distance of 9.9 to 10.0 mm (approximately 0.390”). With pianos like the Steinway, of course, this could vary considerably depending on where the action stack was located and in the end key travel would be determined by how much travel was required to ensure adequate key aftertouch.

As piano hammers became heavier over the years these specifications became some unworkable. To keep key downweight within reason increasing amounts of lead weight would have to be added to the front of the keys. This looks fine for static measurements but the amount of inertia makes fortissimo and fast repetition difficult. The answer was to increase (numerically) the overall action ratio (OAR). For a given hammer mass an action with on OAR of 5.5 (a hammer travel of 5.5 mm for every 1.0 mm of key travel) will have a lighter feel than one with an OAR of 6.0 (a hammer travel of 6.0 mm for every 1.0 mm of key travel). In general manufacturers have kept the hammer travel pretty much standard choosing instead to increase the key travel. This has, I think, pretty much reached its limits now with some actions requiring as much as 11.0 mm of key travel to function properly.

Simplistically, the variables the action designer has to work with are hammer mass, hammer travel and key travel. Still very simplistically, the there are several ways to go about achieving a given OAR; the hammershank length can be varied, hammershank knuckle can be moved closer to or further away from the action center; the contact point between the key capstan and the capstan block on the wippen can be moved and the key balance point can be moved. (Key length is mostly a function of piano length.) If a relatively heavy hammer is selected the OAR will need to be numerically lower and if a relatively lighter hammer is selected a numerically higher OAR can be used. For a given hammer travel and key touchweight the action with the heavier hammer will require more key travel while the action with the lighter hammer can get by with less key travel.


Edited by Withindale (08/24/13 07:59 AM)
_________________________
Ian Russell
Schiedmayer & Soehne, 1925 Model 14, 55" upright
Ibach, 1922 49" upright (project piano)

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#2138136 - 08/24/13 07:52 AM Re: Changing an upright action ratio [Re: musicbased]
Olek Offline
7000 Post Club Member

Registered: 03/14/08
Posts: 7904
Loc: France
The ratio is evaluated using real arm levers at mid blow, generally.

The difference in the 2 butt models proposed by Renner is mostly the cushion thickness (the shape of the knuckle remain the same) both can be used indifferently.

when I was younger the "Faust rules" implied 47 mm for 10 mm dip.

Seem to me that shorter hammer travel appears later, could be with heavier hammers.

on verticals, the mass of the hammer have to do with the soundboard and scale more than with touch.

around 10 mm is considered the goal, assuming the action implantation & design was correct. Once fixed it is a little different on vertical pianos , because the hammer travel cannot be enlarged much without changing the rest angle of the shank and adding heaviness. But within some margin the hammer and the jack travel are looked at in regard of a correct key dip.

The good key height/level help to stay within acceptability margin in regard of the sharps and their placement at mid blow in regard with the line of centers.
The sharps have smaller levers and are nearer the optimal point of contact at rest, which seem to even the touch, they have a little less acceleration than white keys so they do not feel too heavy.
_________________________
It is critical that you call your Senators and Representatives and ask them to cosponsor S. 2587 and H.R. 5052. Getting your legislators to cosponsor these bills


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#2138372 - 08/24/13 03:38 PM Re: Changing an upright action ratio [Re: musicbased]
musicbased Offline
Full Member

Registered: 09/23/12
Posts: 105
Loc: UK
Thanks everyone for the great responses. Very interesting.

Ian, I was a little confused by the OAR of 4, regulating with 45 blow and 10.5 dip, i would have expected more like the 40 blow and deeper dip, but i think it's because the hammer/key travel method for action ratio tends to produce lower figures than the conjugate arms method.

Thanks again, that was very helpful.
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Technician UK
www.soundcloud.com/musicfield

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#2138739 - 08/25/13 12:01 PM Re: Changing an upright action ratio [Re: musicbased]
Withindale Offline
2000 Post Club Member

Registered: 02/09/11
Posts: 2058
Loc: Suffolk, England
Originally Posted By: musicbased
Ian, I was a little confused by the OAR of 4, regulating with 45 blow and 10.5 dip, i would have expected more like the 40 blow and deeper dip ...

Lewis, perhaps the actual measurements may clarify this.

The following figures give the distance the hammer moved when the key was depressed slowly.

6 mm dip => 27 mm hammer travel, ratio 4.5 (Isaac's half blow measurement)
9 mm dip => 40 mm hammer travel, ratio 4.5 (jack trips)
10.7 mm dip => 42.7 mm hammer travel, ratio 4.0 (let off)

With blow distance of 45 mm and let-off at 2.3 mm, 42.7 mm was the maximum distance the hammer reached before it fell back.

When playing, the hammer separates from the jack just after key goes past 9 mm. Key dip of 10.5 mm seems to provide adequate aftertouch, though less than normal at say 11 mm to 11.25 mm.

Hope this helps.


Edited by Withindale (08/25/13 04:02 PM)
_________________________
Ian Russell
Schiedmayer & Soehne, 1925 Model 14, 55" upright
Ibach, 1922 49" upright (project piano)

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#2138844 - 08/25/13 03:28 PM Re: Changing an upright action ratio [Re: musicbased]
musicbased Offline
Full Member

Registered: 09/23/12
Posts: 105
Loc: UK
Yes definitely. Thanks very much for the explanation. smile
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Technician UK
www.soundcloud.com/musicfield

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