• 1.  Screw on Back Checks

    Registered Piano Technician
    Posted 06-23-2022 13:35
    I'm threading new backchecks on old wires.
    I don't recall installing a set like this before, retaining the old wires.
    This vintage Weber has longer and thicker wires than what I could find available, also due to design changes in the action and new bore distance, these will be even a bit higher, I still have enough wire in the new back check for them to be secure.
    I'm aware of other avenues I might have taken, build up the back of the key and redrilling for new back checks with conventional wires ( this piano has tall string hts.) 
    My question is how to fine tune the height of the BCs after install.
    One revolution of the back check may leave it a bit too high or too low.
    It seems obvious, I will have to either tap or press down or lift up, inserting or retracting the wire. 
    Suggestions, comments, techniques please.

  • 2.  RE: Screw on Back Checks

    Posted 06-23-2022 16:49
    When the key is fully depressed and the hammer is held in the 'Drop' position, the top of the b/c should be level with or 2 mm below the hammer tail. 68 to 72 degrees, on the face, to the key. Hopefully your tails are an even length across the keyboard.


    Jon Page

  • 3.  RE: Screw on Back Checks

    Posted 06-23-2022 17:10
    pictures might help . there are some good articles in the PTG Journals on this subject including how to build a jig and how to use a drill press to push new bcs with wires in. You may need to experiment and create samples that will work properly , The fix may require removing the old wires and plugging the holes , tapping new holes , cutting threads on both wire ends,,

    James Kelly
    Owner- Fur Elise Piano Service
    Pawleys Island SC
    (843) 325-4357

  • 4.  RE: Screw on Back Checks

    Posted 06-23-2022 17:38
    I was working on this very thing as you posted. I opted for an alternative method than using the drill press, as that takes some setting up.
    Installing New Backchecks on Old Wires
    YouTube remove preview
    Installing New Backchecks on Old Wires
    View this on YouTube >

    Just posted a video on my youtube channel

    Chernobieff Piano Restorations
    "Where Tone is Key, and Mammoths are not extinct."
    865-986-7720 (text only please)

  • 5.  RE: Screw on Back Checks

    Registered Piano Technician
    Posted 06-24-2022 01:04
    Yes Chris, nice video and pretty much exactly what I'm doing.
    Jon and James,
    I appreciate the info and pressing them in with the arbor press is my procedure with new wires.
    Now, back to what I'm fussing over.
    With the press I can install a set that show a straight line accross the tops, most accurate.
    By screwing on back checks I am stuck at ht that coincides with the back check facing forward, this could
    be a mm or so off, maybe not quite that much.
    BTW Chris, I do like your little ht gauge, better than what I'm using.
    With your guage a punching could be added as needed to follow a custom bore. Adding a punching perhaps every 2 or 3 backchecks.
    Additionally, It is occuring to me that using your guage, Chris, the wire will actually with draw from the hole as the backcheck is tightened down on the guage.
    Leaving the backcheck spaced perfectly above the key.
    I like it. I'm over thinking this, back to work.

    Fenton Murray, RPT


  • 6.  RE: Screw on Back Checks

    Registered Piano Technician
    Posted 06-24-2022 09:00
    Are the bcs threaded into the keys, too, Fenton? If not, they can be pressed farther in. The drill press, as has been mentioned, is a good tool for this.

    Bob Anderson
    Tucson, AZ

  • 7.  RE: Screw on Back Checks

    Registered Piano Technician
    Posted 06-24-2022 15:24
    Hi Bob,
    They are splined, so yes they could be pressed in further.
    I've thought of that and may try it when all are installed and I see
    the need for further refinement in height.
    I would think it will be difficult to affect a mill or two in that fashion.
    When installing new, shiny, teflon coated wires applying an even pressure on
    the press, they glide right in and stop in the same place.
    At this point I need to screw them on and see how they look, then maybe tap a couple down if needed, perhaps a little vise grip on the wire to tap on
    Thank you for responding

  • 8.  RE: Screw on Back Checks

    Registered Piano Technician
    Posted 06-25-2022 16:05
    If you search the journal archives, there’s a great back check article by Richard Davenport from 2008 or so?
    There are diagram of jigs you can make that will easily determine insertion height by fractions of mms.

    Joe Wiencek

  • 9.  RE: Screw on Back Checks

    Registered Piano Technician
    Posted 06-25-2022 18:53
    Thanks Joe,
    I remember the article.

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