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Hello,I am setting up a Steinway action with all new parts.
The string height is fairly consistent except the top treble section where it drops down about 3mm from around note 65.
When putting the action on the keyframe,I noticed someone has removed about 5mm from just the treble end,so there is a gap between the action foot and keyframe,meaning it has to be pulled down with the screws.Presumably to compensate for the string height difference..The rest of the action sits nice and flat.
Is it best to put a packer in the gap to keep the action level?-and have it undercentre?Wouldn't pulling just that one section down put a lot of stress on the keyframe and action?
Not sure whats best to do with it!
Anyone got any ideas??

The Steinway action frame can be bend quite much. If it is not a very old frame it will be okay.
First you should check if the key frame is adjusted correctly to the key bed.

It's always a good idea to check with the manufacturer and see what they suggest. Kent Webb is head of technical support:
email Kwebb@steinway.com

I had a conversation a couple of years ago with Kent about technicians forums. He said "Why don't they just ask us?"

Thanks for the replies Pianolive, that makes me feel better about the bend!-I'm not sure if it's an original steinway procedure or something thats been done later on at some point.
Ok i just sent an email to Kent. Good idea. i hadn't thought about that!-Hopefully he can help with it.

I rebuild Steinway action frames as a sub-specialty, so I've seen many frames both vintage and more recent, after they have become tired.

It is very very seldom that a frame comes in with feet in a dead flat plane, even if the rails are not split and the solder is still good. Why? my guess is that even if a frame is soldered together dead flat at its first manufacture, the process of setting the beveled cleats, and the fact that the feet do not have a ground flat contact surface, mean that each foot, in a random fashion exerts a point load on the cleats and compresses the various cleats in a random fashion.

This point load compresses the cleat at contact unpredictably, and its reasonable that the feet are likewise randomly distorted to accomodate this condition.

As well, one or more cleat might not have been the same thickness as the others at manufacture,or, the cleat was not placed exactly the same as the other cleats. Since the cleats are usually wedges, uneven cleat insertion would mean the cleats were effectively different heights. Given that the cleats are wedges, the placing of cleats is very easy to screw up, even if you know what you are doing. Its time consuming to get it right.

Uneven cleats will force the frame into a contorted shape, especially if a cleat at the middle is shy of the rest. As the middle shy cleat is be pulled down, the end of the frame will lever up over the other cleats, creating a significant lift.

Add to that that sometimes its necessary to bend the feet of a soldered frame to correct a clearance issue with the key sticks. To do this, the feet are usually bent with a pipe wrench, or other fine surgical tool. This will definitely throw the affected foot out of plane.

When rebuilding a frame, unless I'm working with a rebuilder with serious action design chops, I return the feet to a passive fit to the existing cleats. That means I keep the out-of-planeness purposely. If I were to flatten it out, when the frame goes back on the keyframe, the whole keyframe would most likely have to be completely re-bedded.

As far as "did they do this on purpose"...no way. No manufacturer would distort the foot plane purposely. These frames, at the factory, are generic frames. They are not built custom to each piano...they'd go nuts and broke if they messed around like that.

You could prove how it was before you took it apart by putting the keys on the frame, screwing down the entire stack, and then testing to see how the bedding is. If the bedding is okay, chances are it was socked down before you took it apart. If it beds better with a shim, you're golden.

Forcing the feet down puts quite a bit of strain on the whole system, not my favorite, but if you change the way the feet set originally, whatever that was, you will most likely have to correct the bedding.

Jim Ialeggio

Greetings,
If you want the keyframe to provide a stable base for the action you will have to keep the action rails from stressing the keyframe. Either shim the feet so that the action brackets all rest evenly on the keyframe, or bend the rails down. I prefer to shim the feet. If you don't do this, the springiness created in the keyframe will make its bedding weather dependent and it change with the seasons.
Regards,

Concur with Ed on this one. Absolutely.

You want a stable platform for the action. Introducing a decided 'twist' to the assembly by stressing the top action onto the keyframe is not good. It won't be stable. The regulation will wander and the bedding will be problematic.

Shim/wedge the action to fit cleanly onto the frame. The screws are to secure it...not force it into place.

Do let us know what Kent has to say!

Armchair QB
.02-----Ching!

Thanks everyone, thats great.
Very useful information Jim, i appreciate that.
I will check the existing bedding to see if that gives some clues to the puzzle!
I had remembered something about the keyframe bedding being unstable if the feet don't sit flat, which raised my initial concern.

Yes. i will update with Kent's reply too!

Ed, do you always remove the keys before fitting and shimming the stack to the keyframe?

Generally the Key bed to Hammer flange center pin is 5.75" and the repetition center flange pin is 3.25"

Steinway has been very consistent with this.

I would be curious to know where those key bed to center pin measurements fall on your piano.

add to that... what is the consistency of those dimensions across the frame when screwed down with the shim and then screwed down without the shim...measured at 5 of six locations across the frame, not just at one point.

Jim Ialeggio

I am suggesting checking the end in question. Of course, the other end would be good also.

Some corrections to the frame feet and cleats might be possible. Without remaking the frame, one should not mess with the middle cleats. I am thinking, leave well enough alone in the middle.

For Academia, yes, let's know the middle. Good point Jim.

ok, im back in the workshop on monday so i will get back to you with that, thanks Larry.

From memory, (with shims)the HCP is 144mm in the treble and bass.Not sure about the middle at the moment.
With no shims, the HCP is pulled down to around 140mm in just the treble end.

I will have a proper look at all the measurements on monday and report back!

If you are in the UK I suppose the piano is made in Hamburg?
If so, you could contact Steinway House in London, Ulrich Gerhartz.

Actually this one is a NY steinway B, but thats definitely useful to know for any future problems with Hamburg Steinways!

Musicbased,

What is the string height and hammer bore length in the treble?

The bore is 45mm. String height is 190/189mm tapering down in the treble to 187.

I have seen once a top right front foot lowered, but just 1 or 2 mm,
It may have been necessary for tone reasons, using a standard bored hammer with similar bore in high treble than in the mediums as it is the case actually .

I have met a few rare Steinway (originally ?) fitted with shorter heads in the high treble, but most often only the rake angle is adjusted to compensate for the lower string's plane.

Up to 3 mm the lowering of the strings plane in the high treble is not considered a problem , and the height taken in account for the action is in the 5 th octave or in the mediums, allowing for a light 2-3 mm overblow.


usually the height of the hammer center is consistent at 1 mm difference between left and right (center is of not interest as it will be different in the piano than on a table)

I would suppose an improper keyframe bedding creates that apparent difference, 5 mm is way too much in my opinion.

If not, it was an attempt to have a better touch or tone.

Indeed when mounting a new stack the feet are bend

Possibly a stack can be mounted because the center glide bolts are too much lowered, and will take that shape with time, I have met some that where touching on the sides but not on the center.

With the new digital protractors, you can easily see how strong is the string's plane in the high treble, and measure 3°

If the heads are long enough for the mediums, they will be underceetering there, and the energy of the hammer will be delivered only on the front of the head, not the best way to have a full tone.

I agree that any excess stress left in the bedding will lend to variations with seasons, but Steinways are designed originally to accept some (it even lighten the action and allows for an easy pearled tone, but doing so on an action which is not intended for will lend to instability)

Usually I find older Steinway actions with the extreme glide bolts protuberant twice more (and the old hardened oak key frame does not accept much stress) I put that on the desire of the tech to keep some stress within the action, so the extreme bolts are turned a hair from time to time (?) .

I have read that the NY keybed is not similar to the Hamburg, that the stress between the keyframe and keybed is not managed the same, but I have not recent pianos to verify (the older ones seem to have a front lip the same thickness everywhere, is it the case ?).

Usually, with a keyframe laying on a table, the cleats line perfectly (are the same size).

But I know that position modifications are possible, the advantage of a flexible stack.

Jim, to me the bedding is something I tweak depending of the seasons, more on some pianos than others, the wear also may oblige to bed again (the glide bolts can wear with friction)
Bedding the Steinways is one of the most delicate task in grand regulation, I really worked that a lot, that helped me much on other grands, I really refined method and tips, after being able to notice an uneven bedding just with the tone or touch/feel (I have even heard improper keyframe bedding on recordings or detected that on a video !),
As we aim for long term stability, once the first years of the instruments are passed (during those years there may be some key bedding tweaks) I noticed that S&S bedding is really more stable than on many instruments.

Eventually, the inner stress of the action will vary, key dip may change a hair with seasons, but the bedding once stabilized seem to stay solid, needing only really light tweaks every few years.

I have become lately a fan of the old times bedding method, with paper strip^s under the balance rail or glide bolts, without the keys, as a really secure method to find the more neutral bedding.

Tweaks tend to react and change the second day, and as the very even repartition of the action weight on the balance rail always provide an audible clear amelioration in tone, evenness and no "hard spots" I have been happy to see that this old times method is efficient. (one can take the opportunity to clean and lube the pins and mortise at that occasion.)

Different key frames ask for different strategy, so the paper strips method is well adapted to hardwood frames, but it can help even on a Yamaha or a Kawai.

Something I noticed, is that the back of the frame is often warped high due to the weak point where the UC pedal mechanism may pass.

I belive thatr the return spring is pushing there, soI am very attentive to have the UC pedal really tight.
The force of the spring apply half on the leather of the UC movement, half on the left of the cavity, then I cross fingers and hope that this will avoid a warping high of the frame during humid season, and if it happens, that at last the return spring will not have the opportunity to push the frame even higher, as I suspect it can be the case if the UC movement mechanism is not retaining the force of the spring at some point... And I have met old hard wood frames without glide bolts really warped up a lot)

The parallelism between the strong return spring and the side of the action is also checked.

As a principle I never allow any play on the left pedal because of those side effects, supposed or real,

Some brands say you may be able to pull a paper strip from between the action and the cavity as soon the pedal is pushed, others even say that the paper strip can be pulled out with some rubbing with the pedal at rest, I use that last setup.