Pianotech

1.  Key Heights/ Key Dip Huntington Grand

Posted 16 days ago
I have been working on a Huntington Grand Piano and am finally getting some things to work properly. I am not even sure how it played in the first place since there was barely any regulation on it and the hammers where all peeling off the moldings. New hammers/shanks/flanges have made a huge difference and now I am working on the circular process of getting the action to work the way it should. There was only one compacted felt punching on the balance pin and the front pin punchings where green and dried out.

I am wondering what the key height range should be since I can not find any specs on this piano to start from. I know I need to take into account the case partsand the inter-relationship of blow/letoff/drop/key dip/ rep spring/backchecking. I have had to do lots of trial and error as well as research on adjusting the screw type rep spring even testing and replacing some center pins. One article I read last evening on key dip mentioned that some older grands had key dips that went way beyond the commonly used 3/8" . Perhaps someone who has encountered Huntington grand actions has some tips and gottchas....

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James Kelly
Pawleys Island SC
843-325-4357
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2.  RE: Key Heights/ Key Dip Huntington Grand

Posted 16 days ago
I'm not familiar with this particular model. But working on many unusual pianos while working for POS, my final guide was watching the space between jack and knuckle.  
But after I purchased the Fandrich/Rhodes weight bench system, it became easier knowing if the action ratio was off, and where to make changes so it all worked.
-chris





3.  RE: Key Heights/ Key Dip Huntington Grand

Posted 16 days ago
James,

As you mentioned Re the case parts: set sample natural and sharp key heights high enough in all sections such that the fallboard (with felt) closes without clipping the keys. Select an arbitrary key dip by starting with 10 mm (this may change later). Note that dip is set with a typical tapered key dip block, the fat end being the nominal designation (e.g. 10 or 10.2 mm etc.). Do not guesstimate or concern yourself as to what the dip is AT the key pin.

Re action parts:

1) The blow distance is fudge-able, so for now set the hammer shank to 4 or 5 mm off the cushion or rest rail. If no cushion or rail, then set the shank somewhat parallel to the rep lever and/or more or less 90 degrees to the jack. The final blow distance will be set last in this sequence.
2) Set jack to correct position under the knuckle.
3) Set repetition spring strength enough that the rep lever will support the hammer. Make sure that the jack gets back under knuckle and do a quicky rep lever height adjustment.
4) Make sure that hammer tail clears the backcheck, but don't bother to finalize.
5) Set drop to a too-long setting for now. This is necessary so that you can clearly see the letoff in the next step.
6) Set letoff to ~2 mm and don' concern yourself with the excessive drop. If the drop is way long then raise it a bit, but don't finalize.

The blow distance is fudge-able and this you set last. If you don't have an aftertouch gage, then find a thick front rail punching on the order of 0.040" (1 mm) or 0.050" (1.25 mm).

7) Place the punching on top of your front rail punchings and play the key slowly.
8) If the hammer lets off easily in the stroke, then turn DOWN the capstan until the key bottoms out while at the same time hammer lets off with just a bit more firm pressure at the key.
9) If the hammer does not reach letoff when the key bottoms out, then turn UP the capstan until the key bottoms out while at the same time hammer lets off with just a bit more firm pressure at the key.

Remove the aftertouch gage (punching) and the action should cycle through the stroke correctly.

Now the blow distance Re steps 8 and 9, regardless of whether you think it is too long or short, is the correct blow for this configuration and the action will work. The blow distance should be in the 43 mm 47 mm range. Increasing the dip (within reason, consider 10.5 mm max) will allow for an increase in blow and vice versa. If the blow is really short, say 38 or so mm, and you have done everything right, then an action ratio problem would seem to exist.

Action ratio concerns are beyond the scope of this email.

Let us know how it all works out.

Hope this helps.

Nick Gravagne







4.  RE: Key Heights/ Key Dip Huntington Grand

Posted 16 days ago
Nick.. thank you for outlining this approach which I will do sometime this weekend.

    I am sure it will work ands the final measurements will be part of my documentation  I have some rather neat after touch gauges that I bought from Howard Piano . They are color coded with various thicknesses although I know about using the punchings under the front keypin approach
I guess we all need these challenges from time to time. Hopefully there will be no action geometry issues. Will post how things go

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James Kelly
Pawleys Island SC
843-325-4357
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5.  RE: Key Heights/ Key Dip Huntington Grand

Posted 16 days ago
Meant to add Re case parts dry fit. Also put the key slip on. The bottom of the keys should sit below the top of the slip by ~4- 5 mm. The front key pins should extend into the bushings by ~ 3 -4 mm and the tops of the balance pins should extend a bit above the balance bushings.
 
So you see that balancing the case parts visuals with the key elevations will get you there. Be sure that your back rail cloth is in place and of a reasonable thickness. When satisfied with an minor compromises, set your dip to 10 mm to kick things off.

NG

On Fri, Dec 1, 2017 at 1:17 PM, Nicholas Gravagne <ngravagne@gmail.com> wrote:
James,

As you mentioned Re the case parts: set sample natural and sharp key heights high enough in all sections such that the fallboard (with felt) closes without clipping the keys. Select an arbitrary key dip by starting with 10 mm (this may change later). Note that dip is set with a typical tapered key dip block, the fat end being the nominal designation (e.g. 10 or 10.2 mm etc.). Do not guesstimate or concern yourself as to what the dip is AT the key pin.

Re action parts:

1) The blow distance is fudge-able, so for now set the hammer shank to 4 or 5 mm off the cushion or rest rail. If no cushion or rail, then set the shank somewhat parallel to the rep lever and/or more or less 90 degrees to the jack. The final blow distance will be set last in this sequence.
2) Set jack to correct position under the knuckle.
3) Set repetition spring strength enough that the rep lever will support the hammer. Make sure that the jack gets back under knuckle and do a quicky rep lever height adjustment.
4) Make sure that hammer tail clears the backcheck, but don't bother to finalize.
5) Set drop to a too-long setting for now. This is necessary so that you can clearly see the letoff in the next step.
6) Set letoff to ~2 mm and don' concern yourself with the excessive drop. If the drop is way long then raise it a bit, but don't finalize.

The blow distance is fudge-able and this you set last. If you don't have an aftertouch gage, then find a thick front rail punching on the order of 0.040" (1 mm) or 0.050" (1.25 mm).

7) Place the punching on top of your front rail punchings and play the key slowly.
8) If the hammer lets off easily in the stroke, then turn DOWN the capstan until the key bottoms out while at the same time hammer lets off with just a bit more firm pressure at the key.
9) If the hammer does not reach letoff when the key bottoms out, then turn UP the capstan until the key bottoms out while at the same time hammer lets off with just a bit more firm pressure at the key.

Remove the aftertouch gage (punching) and the action should cycle through the stroke correctly.

Now the blow distance Re steps 8 and 9, regardless of whether you think it is too long or short, is the correct blow for this configuration and the action will work. The blow distance should be in the 43 mm 47 mm range. Increasing the dip (within reason, consider 10.5 mm max) will allow for an increase in blow and vice versa. If the blow is really short, say 38 or so mm, and you have done everything right, then an action ratio problem would seem to exist.

Action ratio concerns are beyond the scope of this email.

Let us know how it all works out.

Hope this helps.

Nick Gravagne





--
Nick Gravagne, RPT
AST Mechanical Engineering





6.  RE: Key Heights/ Key Dip Huntington Grand

Posted 16 days ago
As usual, Nick has hit all the significant points.  One other small detail, or clue, when working with a piano full of unknowns like this:  Watch out for keys that bottom out on the front rail pins.  The symptom will be a click, or even a clunk, on a firm key stroke.  That could mean front rail punchings not thick enough of course, but it could also mean balance rail punchings too thin, or back rail cloth too thick, or some combination of these.  (It may merely mean a stray front rail pin a bit high.  These can usually be tapped in a bit to fix that.)

~   Tom McNeil   ~
Vermont Piano Restorations

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Thomas McNeil, RPT
Barre, VT
802-476-7072
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7.  RE: Key Heights/ Key Dip Huntington Grand

Posted 16 days ago
James,
In my beginning career I followed the instructions of my mentor in setting up actions. It never failed me. It’s been so long , let’s see.... set the key height 3/4 “ measuring from top of key frame to bottom of key. Set key slip and follow Nick’s instructions. I think 3/8 key dip will work on most pianos. Blow distance ...I think the length of the key dip block, let off tip of finger from string and back check 3/4” from string.
There you go . Nothing to it.

Sent from my iPhone