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Hammer cupping

  • 1.  Hammer cupping

    Posted 06-13-2018 17:32
    I just have a quick question about hammer cupping.
    I recently was steaming some hammers to bring them back up but I got side tracked and I ended up steaming two hammers twice (Yes dummy me). Now those hammers have now shrunk and cupped like crazy. Now those two hammers barely hit the right string in the tri chord area. Even thought I do plan to replace them in the near future, what could be done to get reverse the cupping (if even possible)?

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    Ruth Zhou
    Canada
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  • 2.  RE: Hammer cupping

    Registered Piano Technician
    Posted 06-13-2018 18:00
    Just sand them flat with sandpaper.  You will want to mate the top of the hammer to the strings. You should do the same with all the hammers.

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    Willem "Wim" Blees, RPT
    Mililani, HI 96789
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  • 3.  RE: Hammer cupping

    Posted 06-13-2018 18:21
    Yup I know I gotta sand it down. But since the cupping, it stars roughly half way between the strike point and the Crown. I was wondering as a last ditch effort if there is any other way such as needling or something that can reserve the shrinking of the felt.

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    Ruth Zhou
    Canada
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  • 4.  RE: Hammer cupping

    Registered Piano Technician
    Posted 06-13-2018 18:32
    I'm having a hard time picturing it.  Can you post a photo?

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    Zeno Wood
    Brooklyn, NY
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  • 5.  RE: Hammer cupping

    Registered Piano Technician
    Posted 06-13-2018 18:55
    If it's like what happens when I put on too much vodka (starting in the string grooves but going too far down on the shoulders and soaking too far in) they are normal height but narrow at the top. I don't know of any way to reverse it.

    I find that vodka in a dropper bottle is easier to control than steam. I call vodka "steam in a bottle". It won't singe my careless fingers, and I don't need to haul a kettle or find an outlet. It does make the piano smell just a little like a cocktail party for awhile.

    Like so many other things, when it comes to either vodka or steam, less is often better.

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    Susan Kline
    Philomath, Oregon
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  • 6.  RE: Hammer cupping

    Posted 06-13-2018 18:55
    Ruth,
    It sounds to me like you need a mentor. The strike point is in the center of the crown. There was no shrinking felt due to the steam which swelled the sides; unless you made them really wet which, then, may have caused shrinking at the center but doubtful.

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    Regards,

    Jon Page
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  • 7.  RE: Hammer cupping

    Posted 06-13-2018 18:48
    Roger Jolly, at a seminar, demonstrated that a cupping hammer can be leveled by deep needling (double needles) along the center of the hammer. I don't know if he was referring to steamed hammers or untreated hammers. But the steam has had more of an affect on the sides than the center, so it makes sense to needle the inner portion of the hammer to allow the center's felt to swell to meet the level of the sides. The center is still under more compression.

    If you sand level, you are cutting across the top layer and the hammer will be prone to a ragged surface.

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    Regards,

    Jon Page
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  • 8.  RE: Hammer cupping

    Posted 06-14-2018 07:39
    How are Ruth and Susan steaming? What methodology? It seems excessive.....

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    Terry Farrell
    Farrell Piano Service, Inc.
    Brandon, Florida
    terry@farrellpiano.com
    813-684-3505
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  • 9.  RE: Hammer cupping

    Registered Piano Technician
    Posted 06-14-2018 08:58
    Just a technicality, but doesn't steaming bring hammers down?

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    Scott Cole
    Talent OR
    541-601-9033
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  • 10.  RE: Hammer cupping

    Posted 06-14-2018 10:59
    I think (from my achieve searches) Susan just drop some vodka on the hammers while I have been using a damp rag and just zapping it with my heating iron. 

    I guess it is time for new hammers.

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    Ruth Zhou
    Canada
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  • 11.  RE: Hammer cupping

    Registered Piano Technician
    Posted 06-14-2018 20:23
    tt's been many years since I used steam. It's actually been a long time since I used too much vodka (on a "gospel damaged" piano) and got the narrowing hammers. I use vodka in a dropper bottle, put right into the string grooves. If some notes are disgustingly bright, I'll put a little bit more down onto the high shoulders, but not too much because of the cupping problem. If hammers are still rock-hard (usually on Korean pianos) and I don't want to use more vodka, I'll lightly squeeze the shoulders with vise grips.

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    Susan Kline
    Philomath, Oregon
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  • 12.  RE: Hammer cupping

    Registered Piano Technician
    Posted 06-15-2018 12:07
    Everyone does realize, I hope, that the reason why the hammers cupped in the first place is due the the fact that when hammers are made, felt is compressed, in a press, to create the hammer.  See my reply to the question about "Why lacquer hammers".  In a nutshell, though, the cupping comes from the fact that, when you steam, or use vodka (one sip for the hammer, two sips for the operator, right?), the sides of the hammer are affected more than the center of the hammer, thus producing the cupping.  I recognize that steaming or vodka produce quick results, but, it tends to be quite indiscriminate and not very controlled in terms of the effect.  Judicious needling to soften hammers is still the best way to produce the best quality sound.  Sure, needling is lots more work, but ... :)

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    Brian De Tar, RPT
    Portland OR
    503-201-5482
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  • 13.  RE: Hammer cupping

    Registered Piano Technician
    Posted 06-15-2018 13:03
    Certainly on a good piano vodka is not indicated unless someone has already done a lot of damage to the hammers. However, for some pianos (read: Korean and similar) the top octave resembles broken glass. One or two drops of vodka right in the string grooves leaves the notes bright but gets rid of the sensation of needles entering one's ears when octave 7 is played in a room smaller than a concert hall. Also, one can even up the voicing by how much one uses on each hammer. (the gamut is from no vodka to 1 drop to 2 drops, not more.)

    Additional benefits of vodka for the high treble: nothing left behind in the hammers except a textural change. Non toxic. Does not remove or shred the limited amount of felt. Can be done quickly but with accurate results once one has had some experience.

    For more miserable cheap too bright pianos, vodka throughout, in varying quantity determined by how harsh the sound is, can get one into a better ball park with very little expenditure of time and money. (Still, one must remember than in excess it deforms the hammers.) Then details can be taken care of with needles, squeezing shoulders, etc. If the hammers are really flat from too much use, vodka will raise a ridge just past the ends of the string grooves, where the felt has been compressed instead of flaked off. So reshaping with a hammer file is needed.

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    Susan Kline
    Philomath, Oregon
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