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#3102722 04/06/21 10:26 AM
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Hi folks,

I've got a 1920's Heintzman grand with a damaged damper undertray. The pivot pin has broken the tray itself and of course now the dampers are a mess since once side doesn't have the vertical integrity the pivot hole used to provide.

Aside from replacing the tray, has anyone ever seen/repaired something like this? I've not run across this before. Pic below.

Thanks in advance for your help!

Rob

[img]https://imgur.com/a/lnOASPv[/img]

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I would not have an idea for repairing that damaged hole but you may be able to do a custom modification and if it’s possible it would last a good while and improve damper function snd regulation. There may not be room to do this looking at the photo but consider the idea.
It would involve relocating the damper tray pivot pin so it aligns with the lift lever center pin. You would glue a wood block on the end of the tray and drill a hole for the tray pivot pin in line with the lift lever center pin. Then you would need to consider how to relocate the mounting blocks that the other end of the tray that the pins mount to.
It’s not that difficult.
If it’s possible to do this sort of modification you may need to modify the tray return spring

Last edited by Gene Nelson; 04/06/21 11:10 AM.

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I suspect you could rout out the area where the pin should go, and glue in a piece of wood to hold a pin.


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First, draw some index lines to find the center of the hole after you repair it. I would pop the last flange off, chisel a 3/4" square cavity at the end of the tray and epoxy a 3/4" cube of pin block material. use the two index line on the end to locate the original hole, and drill for it. Return the last flange, and you are done. '
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Thanks for your suggestions, folks! I suspected it would be a dowel treatment of some sort. Gene, I've also considered moving the pivot point - but I am concerned with the change in geometry that would occur - instead of the tray pivoting from the top rear corner, somewhere closer to the middle of the tray. Perhaps it would be minimal, and I suppose the impact could likely be regulated out of the damper system - but I'm hoping to constrain the number of variables at play while effecting the repair. Thanks for the suggestion!

Cheers all!

Rob

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Originally Posted by RobC
Thanks for your suggestions, folks! I suspected it would be a dowel treatment of some sort. Gene, I've also considered moving the pivot point - but I am concerned with the change in geometry that would occur - instead of the tray pivoting from the top rear corner, somewhere closer to the middle of the tray. Perhaps it would be minimal, and I suppose the impact could likely be regulated out of the damper system - but I'm hoping to constrain the number of variables at play while effecting the repair. Thanks for the suggestion!

Cheers all!

Rob
If you decide to try relocating the pivot pin the damper geometry won’t change if you relocate the pivot pin in the mounting blocks the same distance that you moved the pivot pin from where it was originally and keeping the same height above key bed.
You may need a stronger tray return spring.


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Gene - I see now what you mean, of course. Thanks for clarifying - considering this!

Rob

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To add to Ed's excellent method. Before you pop the glued flange off, (and you pop it off bu using a putty knife between the flanges, and you can reinforce the neighboring flanges adhesion by using a clamp so you can lever against it to pop the end one off), Put some masking tape on the lift tray felt and mark with a pencil the position of the end lever for use when you reglue it.

You might want to see if a balance rail pin might fit for a new pin and the longer length will allow for more wood to hold it. Be sure to drill for the longer length.


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Originally Posted by Gene Nelson
Originally Posted by RobC
Thanks for your suggestions, folks! I suspected it would be a dowel treatment of some sort. Gene, I've also considered moving the pivot point - but I am concerned with the change in geometry that would occur - instead of the tray pivoting from the top rear corner, somewhere closer to the middle of the tray. Perhaps it would be minimal, and I suppose the impact could likely be regulated out of the damper system - but I'm hoping to constrain the number of variables at play while effecting the repair. Thanks for the suggestion!

Cheers all!

Rob
If you decide to try relocating the pivot pin the damper geometry won’t change if you relocate the pivot pin in the mounting blocks the same distance that you moved the pivot pin from where it was originally and keeping the same height above key bed.
You may need a stronger tray return spring.

Speaking of the location of the tray pivot, it has always struck me as a bit bizarre that the tray pivot is not collinear with the damper-arm pivots, and, in fact, is often quite far away. The WNG back action has fixed this problem. I don't know if anyone else has done so.

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Iv installed a couple WNG back action kits - SS and others needs a Bruce Clark type engineer/innovater.
Tokiwa or Renner kits I have modified to align pivot and lift lever center pins but the kits are designed for the traditional misalignment.
A better way of doing things I suppose forces manufacturers to admit poor design?


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Every new Damper action I install has the underlever and lift tray pivots concentric. The Tokiwa kit is quite easy to establish this with.

Most pianos have poorly engineered trap work systems too.


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The Tokiwa kits come with the end blocks predrilled to Line up with the damper lever flanges and have been that way for quite some time. I built a Tokiwa kit just yesterday. Tomorrow I'll be installing dampers.


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Originally Posted by Gene Nelson
Iv installed a couple WNG back action kits - SS and others needs a Bruce Clark type engineer/innovater.
Tokiwa or Renner kits I have modified to align pivot and lift lever center pins but the kits are designed for the traditional misalignment.
A better way of doing things I suppose forces manufacturers to admit poor design?

Question: are you sure it is poor design, or is there a reason for it that you simply don't know about?

Answer: Yes, there is a reason. It has to do with giving the pianist more smooth and controllable ½ pedaling.

The Kawai production actions all have the tray pivot aligned with the damper lever pivots, as technicians like them. The Shigeru Kawai pianos all have the tray pivot located differently from the damper lever pivots intentionally. This causes the pedal to pull back on the damper levers slightly, so that the pedal motion lifts the damper heads very slightly at the rear before the front.

When the Shigeru pianos were introduced at NAMM 2000, during the course of the show 2 very fine pianists who separately tried them out commented to me that they felt the pedal operation was much better than regular Kawai pianos, that the ½ pedal operation was much more smooth. These were completely blind comments, unprompted and without previous knowledge by the pianists that anything was different.

Recommendation to rebuilders: do not 'correct' this misalignment just because you think it makes sense. Leave it as the very smart piano designers set it up.

Don Mannino

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Admittedly there are many back action design reasonings and purposes that I am not familiar with.
However, the retrofits that I have done allow opportunity to do more than concentric alignment of tray and lift lever pins.
After careful action regulation and new key end felt I can change the height of pivot pins so that the damper tray is parallel to the key ends, making regulation much easier.
Or I can relocate the tray return spring closer to the tray lift Pittman to help eliminate tray warping.
I can install capstans to make regulation easier.
All have obvious benefits and all likely ignore the original design purpose.


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As with all things piano related, there are compromises involved. An off set tray will give you a "softer" landing with the dampers, but it requires the damper up-stop rail to be set higher resulting in more bounce of the dampers on the end of the key. That is something that bothers me when I'm playing.

It is best to discuss these things with the pianist to see what they consider most important.


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In my limited experience, if the pivot points are not concentric, then the down limit (no pedal pressed) position of the damper tray must be quite close to where it would start to lift the dampers. Else, the interaction between the damper tray position and the individual damper arms can become quite problematic--I speak from experience. In terms of half pedaling, I have often wondered why the leverage of the Steinway, and no doubt many other, damper pedal design is such that to go from no pedal to full pedal requires such a small amount of movement of the foot. It has struck me that if the leverage were just maybe 50% lower, then the pedal would be so much easier to control, and that would, of course, include 1/2 pedaling. I'm sure many readers will tell me that the Steinway damper-pedal travel is just perfect, and to each his own, but having serviced a Steinway pedal assembly, it is my suspicion that the lever ratio is, in good part, a function of cost control and simple design of the pedal mechanism. (Call me cynical if you want, but I have enough experience looking at the designs of a number of commercial products to see many cases where design compromises leading to less than optimum performance become praised by users as the consumer gets used to them.)

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There are other back action design ideas that in my opinion were in need of upgrade like installing a leaf spring for damper tray return at the upper end of the tray, what’s that all about - warped tray.
Or fixed sostenuto tabs, ok but difficult to regulate.
Thank Yamaha for that nice conversion kit that allows you to mount the sostenuto lift rod on the belly rail - I think WNG makes one too. Or lift levers that have mounting flanges that are verticle with screws as opposed to horizontal and glued, no need to remove the entire tray to service that one lever that fails.
Don’t know but it’s likely rebuilders that contribute many of these ideas and rebuilders should have a cooperative relationship with manufacturers. Both have good and bad ideas.


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So Don, is Kawai going to adopt the original "riding" pitman that Steinway used for over 100 years? The one that digs into the pressed felt bushed hole in the keybed and slides in a jumpy fashion on the buckskin on the bottom of the tray? The one that get all kinds of grease and graphite smeared all over the place to solve pedal noise? That is the "original" engineering.

That one sure is a source of user complaint in my experience.


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This is slightly OT, but it may be of interest to those of you who have been installing WNG damper actions with the belly rail mounted sostenuto kits. As you know, the stack mounted sostenuto system that is part of a Steinway grand will not work with the damper underlevers and top flanges that are part of the WNG damper action, they can't occupy the same space. This requires the use of the WNG belly rail mounted sostenuto system to avoid that.

All good except for the belly rail mounted bracket with support block that must go adjacent to the plate strut in the bass-tenor area. As an example of a difficulty, I have a 1916 Steinway O in my shop, where the end of the strut that intersects the belly rail wall forms a T with 2 large screws attaching to a recess in the belly rail. That space is about 70 mm in width. In order to mount the bracket to the belly rail wall and have the support block on the belly rail mounting bracket be located immediately adjacent to the sostenuto pitman would require an offset of about 75 to 80 mm. Or one can devise a way to mount the bracket on the keybed in a very small space to avoid all conflicts.

Apparently, WNG has had these out for a while, but they have come out with a tall underlever top flange, where the spring tab sostenuto is sitting 7 mm. higher than the WNG originals. It is designed for Steinways. This means you can use the original Steinway stack mounted sostenuto system, and have the clearances you need.

I have not installed the underlevers yet, and am returning my original WNG underlevers and having them substituted with ones with the tall underlever top flanges. I will likely install them late next week.


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