Pianotech

  • 1.  Tight Teflon bushings

    Registered Piano Technician
    Posted 11-03-2023 11:25
    Curious if there's any treatment that would ease tight bushings causing sluggish hammer flanges.
    Thanks
    Christopher


  • 2.  RE: Tight Teflon bushings

    Registered Piano Technician
    Posted 11-03-2023 12:43
    Hi, Chris,

    Higher relative humidity.

    If the tight bushing symptoms are present at 40-45%RH you need to service the bushings with the proper set of Johnson Carbide reamers as prescribed by the Steinway Service Bulletin.  But if your RH is an episodic 20%RH, then the remedy is to increase the RH to normal ranges.

    Bill




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  • 3.  RE: Tight Teflon bushings

    Registered Piano Technician
    Posted 11-03-2023 19:49
    Thanks Bill,
    It's definitely not dry  here in northern California so it looks like repinning is the prescribed treatment which I am not prepared to do on this consignment M. Since the knuckles are hard as rocks I'll advise my client to replace the shanks and keep the hammers that are in excellent condition. 

    Christopher



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  • 4.  RE: Tight Teflon bushings

    Registered Piano Technician
    Posted 11-03-2023 22:40
    Hi Chris,

    I was aware of your location when I wrote;  I was in Napa Valley last weekend and the RH was less than 20%, maybe 6-7%.  PG&E was threatening to shut down the power due to the "devil winds."  That's actually what I was thinking about when I read your piece, that it might be a temporary thing.  You guys have the same situation as we do with Santa Anas in southern California, extreme dry periods of varying length.  I'm not sure that is what is the cause of the teflon action's sluggishness, but I have seen that exact thing here and remedied it with increased RH.

    I see Marin County is about 60%RH right now.....but on October 29 it was as low as 15%.  FWIW  :)    Past Weather in Marin County, California, USA - Yesterday or Further Back (timeanddate.com)

    Even if this is the main cause of the sluggishness, replacement is always preferable to fighting those things!

    Regards,

    Bill






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  • 5.  RE: Tight Teflon bushings

    Posted 11-03-2023 23:09
    Hi,

    There's more yet. In Marin County, there are hundreds of micro-climates. There are too many variables. What works in one area might be a disaster in another.

    Teflon bushings, as used by Steinway, went through a number of iterations. There is no one-way-to-do-it solution that is truly predictable. One does what what can with the environment; and then works with what is left.

    I disagree that problems automagically require replacement. Sorry.

    Kind regards.

    Horace






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  • 6.  RE: Tight Teflon bushings

    Registered Piano Technician
    Posted 11-04-2023 10:40
    That reminds me of the old Steinway classes, Bill. They used to drop a teflon Sh&Fl into a glass of water. After a while they took it out and the flange moved freely.

    Bob Anderson, RPT
    Tucson, AZ


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  • 7.  RE: Tight Teflon bushings

    Posted 11-05-2023 10:21

    Christopher, I would recommend staying with the teflon bushings. Good engineering (with certain issues). I would assume that one option is to remove the center pin, glue size the hole in the wood flange, and replace with a smaller size pin.

     

    Regards, Norman



    ------------------------------
    Norman Brickman
    Potomac Piano Service
    Potomac, Maryland
    potomacpiano@verizon.net
    https://potomacpiano.com
    (301) 983.9321
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  • 8.  RE: Tight Teflon bushings

    Registered Piano Technician
    Posted 11-22-2023 14:29

    Given the lapse since this was originally posted, I imagine that Chris has taken whatever steps he feels necessary.  Still, I'll add on from the Steinway Service Bulletin Specifications and Service Techniques (p15-16) that carefully roughened and measured center pins of the appropriate sizes can also work, however, the persistent weakness of these discussions is that they remain one or two degrees from specific.  Both Bill and Horace pointed to the sort of micro-fluctuations you're potentially dealing with there.  There is, unfortunately, no mention of specific friction measurements (grams), so it's impossible to have a sense of just how seriously the action is impacted.  Even assuming sufficient skill in this particular operation, it still requires judgment, since some amount of excess friction would still be acceptable, while erring in the opposite direction sill introduce clicking, in elevated humidity.  It's also not clear whether this is a spot problem or pervasive. Lastly, it's unclear whether the repetions are also teflon and, if so, whether they exhibit similar issues (jack, rep lever, flange). 

    If the hammers are, in fact, still fine, would that mean that they are not original?  If not, how recently were they replaced?  Does the action geometry support the (likely heavier) hammers?

    Last - knuckles can be replaced. Fairly straightforward if not changing the position.  Compare to the cost and effort of replacing shanks... that will likely need repinning anyway.



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    David Skolnik [RPT]
    Hastings-on-Hudson NY
    (917) 589-2625
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  • 9.  RE: Tight Teflon bushings

    Registered Piano Technician
    Posted 11-22-2023 16:23

    I have had "some" success with tight teflon bushings with fomblin. However my latest attempt was with TSI 321. Seemed to help. Not expensive and super slippery. 

    Peter Grey Piano Doctor 



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    Peter Grey
    Stratham NH
    (603) 686-2395
    pianodoctor57@gmail.com
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