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Dear techs,

I investigated the heavy touch of my recently acquired Ibach upright. With the right pedal pressed, it actually plays quite easily, so I re-measured downweight and upweight with coins of 4 g each, with right pedal pressed. DW is about 52 to 56 g, UW about 20 to 24 g (some notes 16 to 20 g). This is pretty normal, according to Arthur Reblitz.

It seems that the dampers are what makes the touch so heavy. I took out one damper lever and inspected it. The end of the spring that runs in the felt punching was slightly dirty and sticky. (Presumably gummed-up old lubricant.) A bit of solvent cleaned this quite easily. The nickel plating of the spring has also been worn through to the copper. The lower felt against which the damper spoon presses, was slightly compacted, but clean.

See pictures here:
http://picasaweb.google.com/lh/photo/QzTV7SxomryLqzLNPsd5_Q?feat=directlink
... and the following 4 pictures.

The center is also a bit tight, but what really struck me is that the damper spring was quite strong. (Too strong, I wondered?)

Could it be that the touch of this piano is so heavy simply because it has strong damper springs?

Is there a rule of thumb how much force (in grams) the dampers should exert on the strings? Or, what the downweight should read with the right pedal up?

By the way, the right pedal is also significantly harder to press than the left one.

I am not a Technician. I am a Piano user like you.
I think, how heavy the touch of a piano depends partly on its damper springs. Definitely.
The parts that make the touch of a key includes:
The mass of the key, the parts that move the hammer, the hammer itself, and the force of the damper spring.
I agree that the right pedal is the hardest of all.

I want to ask all of you the questions I have asked at the other thread:
What is the characteristics of the ideal damper pedal?
Is it the kind of on-off damper action, or the continuous controlling action?
How the strings vibrate when the damper has not completely separated from its strings? Is it produces a good sound?
How the strings vibrate when the damper gets back to its position pressing on its strings? Completely mute? And that is the best or a little vibration is the best?
Assume that when the damper pedal is pressed to the floor, a string can vibrate freely to a minutes long, then when the damper pedal is half way pressed, the string can vibrate only 30 seconds or about that long?
Assume that you are a technician who design the damper pedal, do you want it has 2 moods: one for on/off mood and other for continuous damper controlling mood? So that you can play on damper, off damper, and half damper, or 1/3 damper, or 3/4 damper, or something in between these values?

Thank you in advance.

Mark,
The amount of resistance that the damper mechanism adds to the touch can be significant. Two general factors are:
1) Damper Timing. Early pickup creates a "heavier" feel
2) Spring Tension. Heavier than need for damping adds to touch resistance.

Further . . .
I notice in your photos the contact felt is quite deeply dented/worn where the damper spoon on the end of the wippen contacts it. This can add to resistance in and of itself. Additionally, the spoon can be rough or at the wrong angle so that it gouges into the felt -- not only promoting wear but adding greatly to friction.

Cheers,
--Keith

Yes, the touch weight is probably heavy because of the damper springs. The real question, of course, is why and what can be done about it?

You do not say how large your Ibach piano is nor do you give us any indication of its scaling. But let's assume it is a reasonably powerful vertical piano. These pianos can be difficult to damp for several reasons; the most significant of which is the lack of mass in the damping system.

Picture a grand piano with exactly the same scaling—the damper mechanism will almost certainly be operated primarily by gravity. Sometimes there are assist springs but they are really unnecessary except in the very low bass and even here their force will be minimal. Even though the force of the grand's damper felts against the strings (the result of gravity working on the various parts of the damper system) will often be considerably less than the force of the spring operated upright damper pressing against the strings the grand damper mechanism will always operate more efficiently.

The problem is that damper system—whether it be in a grand or a vertical—needs a certain amount of mass to dampen the energy of the higher string partials. In the grand system this is no problem; the necessary mass is inherently there. In the upright damper system action manufacturers have been systematically removing mass (i.e., making the parts smaller and lighter) to save cost. Then, when a pianomaker has problems with damping the action makers simply supply stronger and stronger damper springs.

These springs make the touch heavier—and make controlling the action at pianissimo levels virtually impossible—but they do little to make damping more efficient.

There is at least a partial solution available. At least one of the European piano parts suppliers sells brass damper barrels. These add enough mass to more efficiently damp the vibrating energy of higher string partials. You—or your technician—can remove the wood barrels and replace them with the brass barrels. Usually no other modifications are necessary. You can use what we call PVC-e adhesive (check with the piano parts supplier, they can probably offer some advice on appropriate adhesives available either in your area or from them). Once the more massive damper barrels are in place you should be able to decrease the amount of spring force. You will have to experiment some to find out just how much tension you can take off of the springs.

ddf

Del -

My Ibach is about 110 cm (43") high. I'm not sure how to describe the scaling - perhaps you can point me in the right direction? I can give data in terms of the position of the tenor and treble breaks, as well as wound monochords, bichords and plain trichords.

What I can say, is this: all damper barrels are of wood - no brass there currently! Many thanks for the idea to replace wood with brass.

And yes, the action is difficult to control at pianissimo. Although, granted, let-off needs to be regulated.

Many thanks for your inputs.

Let me add that I service one of the pianos Del designed (Fandrich upright) and the damping on that piano is superb -- even though it has the power of a grand!.

For some time during the 1990s we built a 122 cm vertical piano. This piano had a rather strong scale and was difficult to damp. On the prototype I tried many things to improe the damping but nothing was satisfactory--not even the strongest springs Renner was able to supply gave the piano good damping. The problem was not solved until I fit the piano with brass barrels. That worked and I was able to use much weaker springs. Pianissimo was excellent.

ddf

It doesn't take long to weaken the damper springs a bit using a spring hook. Simply grab the spring, pull it back towards the hammer butt once, slip it back into place. Just keep the pull even from one damper to the next. On pianos I've done this on, the springs were very strong, and it made a huge reduction in touch weight. Don't over do it or you will certainly create damping issues. One pull on the spring is usually enough.

By all means try just weakening the damper springs first. It is the easiest thing to try and it might work without further modification. If you find you cannot weaken them enough to make the piano more playable and still get good damping then try the brass damper barrels.

ddf

Keith:
The damper that I inspected and cleaned was G4, i.e. it's in the most-played section of the piano. With this amount of indentation, would you consider replacing the contact felt, or would this be premature? I did look at the spoon, and it was very smooth, in fact it looked quite polished. One could also see that it contacts the felt face-on, i.e. no gouging. Isaac (Kamin) actually pointed out to me when I was considering to buy this Ibach that the 70's Renner actions on smaller uprights tend to wear out their contact felts - in extreme cases, the wippen can actually be blocked. I have no frame of reference: what amount of indentation is still acceptable?

Del:
I'm not sure what sort of information is required in fully describing a piano's scale, but I had a quick look at some details.
* Height from bottom board to top lid = 110 cm (floor to top = 112).
* All dampers have two felt cushions and all have wooden barrels.
* A0 to A1 = wound monochords.
* Bb1 to F3 = wound bichords damped with wedges.
* F#3 to Eb5 = steel trichords damped with flat dampers (no double wedges in this piano), both cushions of which are stitched, with the upper cushion pressing harder on the strings than the lower one, i.e. top end of the damper head is somewhat closer to the strings, so that the lower cushion has hardly any string grooves. All of them are aligned in this way, hence I presume it's intentional.
* Tenor break is between Eb3 and E3, i.e. two wound bichords to the right of the break.
* Treble break is between F#5 and G5.

If damping is insufficient after weakening the springs, I suppose I could try temporary clip-on weights to evaluate whether brass barrels would do the trick.

Anyhow, before I touch the damper springs, I'll see to it that the rest of the action does not have excessive friction. (Some butt centers are a bit stiff.)

I appreciate all the answers - I had wondered whether spring weakening is a viable option.

Without seeing them for myself it's hard to tell. I only looked at one picture and, while certainly indented, they didn't strike me as completely worn out yet. These tend to wear faster with excessive damper spring pressure. Reduce the pressure of the springs and what is left will last longer.



To evaluate a scale requires the speaking length of each note (to the nearest mm through the bass and tenor; to the nearest half-mm in the treble. Plus the diameter of the plain steel strings and the diameter of the steel core plus the overall diameter of the wrapped portion of the strings.



You can. I have used split fisherman's weights to clip on to the damper wire. It is not as effective as the brass barrel (which is more ideally located immediately behind the damper felts) but it does sometime work quite nicely.

ddf

Thanks, Del, for the clarification.

I had to Google "split fisherman's weights", but understand now what they are. (Also called split shot.) Ingenious idea!

The felt "should" be replaced. The friction with the spoon and the cavitated felt has to be at least triple what it would be if the surface were flat due to the increased contact area. But there's not much point in doing it until you address the spring tension issues -- which almost certainly is the larger contributor of your touch resistance problem.

Again, my thanks to all of you.

Yesterday evening I tested the damper springs' effective "downweight" by lifting the hammers to the string and testing the feel of the keys - both down and up - in the lower half of the key dip. I chose one or two sample notes that felt particularly heavy and carefully eased their springs, to get a feel for this. I could adjust the strength to bring them more in line with neighbouring notes, without losing damping effectivity.

Thanks, Keith, increased friction due to larger contact area - makes sense to me. Downweight, by the way, almost doubles (mid-50's to perhaps 100g !!) when some spoons engage. If I remember correctly, the upweight of some keys, with dampers engaged, exceeds 50g, i.e. the key actually starts to lift my normal test weight for downweight if I release the right pedal.

I'd be interested to know whether there are similar guidelines for downweight and upweight with engaged dampers, as there are for disengaged dampers. Or, perhaps, for damping alone (hammers are hand-held at the string).

Here's a bit of feedback.

I've stretched/eased all the damper springs to reduce their string-damping force by about one third. Holding the flange at right angles to the lever, I found forces of up to 90 g in the bass and about 35 g in the high treble, sometimes with quite severe fluctuations on neighboring notes.

I decided to do this job with the dampers out of the action, because the springs and their felts were all gummed up with old, sticky, greasy goo - presumably the remnants of 40 year old lubricant. I cleaned all of them.

Here's a "before" picture:


And the same felt and spring "after":


I've also successfully eased the damper centers using a mixture of water (30%) and denatured alcohol (70%) - in most cases, only one pass was required.

I then tried to clean the spoon and rod marks off the lever cloths in a similar way as the spring felts. Some spoon marks were quite dark, and the dirt came away well. The rod marks, however, remained. (Perhaps verdigris from the brass grub screws?) The required brushing helped to restore some of the spoon-indented cloth, but I'm still considering to try and improve this using a moist cloth and hot iron.

Then, after I've polished the spoons (some aren't all that clean after all), I'll reassemble the action and test-drive.

Any suggestions on lubrication of the spring and spoon cloths? (If any?)

And some more feedback.

I've now also polished the damper spoons with a Dremel tool and a dry felt polishing disk. They weren't as clean as I'd first thought.

I also treated the damper cloths by spraying them with a fine water mist and ironing them with a hot iron.

Before:


After:


This was one of my first attempts - later I used slightly more moisture, heat and time, and hardly any spoon indentations were left.

I checked the glue of the cloth immediately after ironing, and it did not soften noticeably.

Looking forward to the first test when everything is reassembled...

I finally had some time last night to re-assemble the action. For anyone interested, I shot a little video to show how I work. Unfortunately, it's a large file (more than 200 MB) - I'm not familiar with the various movie formats and converting a movie into a space-saving format.

http://www.youtube.com/watch?v=G5yE2C5lZLs

Anyway, with the damper centers and hammer butt centers eased, damper springs eased and cleaned, spring felts cleaned, damper spoons polished and the damper cloths ironed, the Ibach plays much better and more evenly. The dampers should probably be eased even more, and the damper timing must definitely improved, but I'll leave this for a later stage.

I wanted to thank all the techs who made good and useful contributions here.

It feels like a good start, and I'm happy!