Pianotech

Subject: Strike point

1.  Strike point

Posted 11-10-2017 08:54
I need to rehang the treble most hammers in a grand to adjust to the strike point. I have identified how far they need to move buy moving the action in and out to get the best sound and know about putting tape on the keybed and marking the starting point of the keyframe and the the corrected point to get how far to rehang the hammers. My question is how to transfer the measurement on the keybed to the hammer when rehanging? What are some ideas to determine that the hammer has been rehung in the correct position? Where does one measure from? What is the reference that can be used to preposition the hammer? All of those are the same question stated different ways. Hopefully I have been clear.

Thanks.

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Rex Roseman
Akron OH
330-289-2948
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2.  RE: Strike point

Posted 11-10-2017 09:10
Hi Rex,
If you scribe a line though the center of the hammer molding, perpendicular to the hammer shank, you can then measure the distance from the hammer flange center to the scribed line. Next, you can make the change in this distance based on your measurement on the keybed. Make sense?

All the best,
Jon






3.  RE: Strike point

Posted 11-10-2017 10:44
Assuming you're moving the hammers in and not out - pop off the hammers and reglue so that the length of shank sticking out from the top of the hammer is the length you measured on your two positions marked on the tape on the keybed.  Make sure you duplicate the rake angle!

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Zeno Wood
Brooklyn, NY
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4.  RE: Strike point

Posted 11-10-2017 12:52

I try to first verify that the whole action doesn't need to come out by checking the sound in the lower capo section at both positions.  Make sure some sample hammers are shaped well and fitted to the strings, then listen in both spots.  I'm figuring you already did this, but thought some others might benefit from being reminded that the lower area matters, too. ��

 

 I like to first re-mount only#88  by offsetting it from the lower hammers in the existing position. A small ruler aligned to the strike points of the lower hammers extending up over#88 will allow you to precisely compare the new strike point with the old position.

 

If all the hammers are uneven from a badly replaced set, then measuring the shank length is a good plan. Check with a protractor for 90 degree angle, and you may need to correct that as well, or just duplicate what it was if it was good for the piano.

 

 After#88  is dry and checked for good sound in the new position, then pop off the other hammers and reglue them in a new line up to#88.

 

Don Mannino

 






5.  RE: Strike point

Posted 11-10-2017 19:20
I use the 'rule of 72'.  You have enough info now to set note 88. I will then set note 72 at 11/32" as a starting point (saliva on the hammershank​ should keep ot in place for this process). Move it in or out till best overall sound is achieved...then glue it. Strike line is then from note 88 to note 72, then 72 to note 1.

BTW, WNG sells a nice little tool precisely for this purpose.

Pwg

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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
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6.  RE: Strike point

Posted 11-10-2017 22:59
Mark center lines on hammers 88, 83, 78, 73, and 68. Center the action position for proper fit in the action cavity. Measure speaking lengths of same notes indicated in first sentence. Multiply the speaking lengths by the following factors to determine how far the center of the hammer should be from the front edge of the V-bar:
Note 88  .064
        83   .075
        78   .085
        73   .089
        68   .094
Millimeters are easier to work with but the factors work with any unit of measure.

I derived these from much testing and evaluation over time. They do depend on the V-bar being shaped to a V-shape. If the bar is a typical round U-bar, the measurements degrade in accuracy.
Hope this helps
Ed

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Edward McMorrow
Edmonds WA
425-299-3431
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7.  RE: Strike point

Posted 11-11-2017 08:29
Edited by Jim Ialeggio 11-11-2017 09:27
<Mark centerlines on hammers


Ed...I locate the distances as per your ratios, but prove the actual as built strike location on the hammer, which may or may not be top-dead-center, depending. As I custom bore, it usually lines up tdc, but in a generic bore, top-dead-center is not a given to measure to.

Thoughts?

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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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8.  RE: Strike point

Posted 11-11-2017 22:26
Thanks Jim for the correction,
Yes I do mark the top dead center line across the crown of the hammers. I didn't say that precisely in my post.

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Edward McMorrow
Edmonds WA
425-299-3431
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9.  RE: Strike point

Posted 27 days ago
Thank you to everyone that replied. I had moved the action to the back of the action cavity to improve the top octave and found that octave 5 and 6 went dead. Moved the action back and checked the hammers. The worst offending hammers were shaped so the strike point was not lined up with the core. Upon refiling and moving the strike point back where it should be, the notes came alive. I will continue to check other suggestions and see if I can get more improvement.

The issue here was that the string height on this piano is too high and the last set of hammers installed were stock boring and to short and could not be made to work..This set was custom bored for the action/string height relationship and work great. The problem occurred when hanging the new hammers. The hanging jig was adjusted to the original hammers, but because of the different bore distance, the distance from boring to the end of tail was different and the new hammers rested in a different place then the original samples in the jig. I discovered it after hanging the first few treble hammers and readjusted for the rest of the set, but was not sure if I got the top hammers correct until it was put back in the piano and did not work optimal. I may still have to rehang the top section, but now have more to look at before I do that..

Thanks again to all that responded.

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Rex Roseman
Akron OH
330-289-2948
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10.  RE: Strike point

Posted 27 days ago
This wouldn't perchance be a Samick product would it?

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Geoff Sykes, RPT
Los Angeles CA
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11.  RE: Strike point

Posted 27 days ago
Steinway D

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Rex Roseman
Akron OH
330-289-2948
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