Pianotech

I am getting ready to install a set of hammers. I am already planning to add about 1mm or so to the hammer bore measurement to compensate for future hammer wear, so the hammer will understrike just a little bit after installation. 

But I am also thinking that I should probably add a little bit more to the bore length to compensate for initial hammer prep, which will include mating the hammers to the string, using a piano pounder for a number of hours, and the final voicing of the hammers. After doing all the hammer prep and piano pounding, I would still like to end up with the 1mm extra length, as mentioned above, to compensate for future hammer wear.

Should I add another mm or more of hammer bore length in addition to the 1mm added for future hammer wear? How do you experienced techs handle this issue?

Thanks!

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Joe Burros
Cell: 646-410-7174
jbcello@gmail.com
www.fmi-newengland.com
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Joe,

Golly, that's al lot of "So"s!

Now to the point, I always added 1.5mm, for several reasons, one being the matter you're concerned with.

David G. Hughes, RPT

Baltimore Chapter

Hi David,

You are right, too many so's in my post. I took them all out except for one so. I guess I was feeling just so, so when I first typed it.

Joe

So, David, I have a question. After you are done with all of your hammer prep, hammer to string mating, piano pounding (if you do that), and voicing, how much extra blow distance are you left with to compensate for future hammer wear? 

Joe,

There wouldn't be "extra" blow distance, there would be reduced blow distance. The "taller" the hammer (the longer the bore distance), the less blow distance there is given a uniform shank height at rest across the action.

I never really worried about blow distance, I concerned myself with let-off, key dip and aftertouch. Once I had these three elements where I wanted them, the resulting blow distance was whatever it was. I never measured blow distance. What the pianist feels is let-off, key dip, and aftertouch. Blow distance is merely something we technicians talk about.

David G. Hughes, RPT

I don't, I prep the hammers (preneedle, file to square the crown and remove the cupping) before I bore them and then bore them as the center pin/string ht differential dictates.  If you wanted to add 1.5 mm (1/16th") I don't see any harm.  Depending on how much you add, it might change your strike point in the treble a bit but should be easily compensated with the cheek block adjustment.  Bass end is not critical that way.