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flange screws that won't stay tight

  • 1.  flange screws that won't stay tight

    Posted 11-12-2018 17:02
    I've been working on an older German vertical (1920s-30s). I took the action home to service, among other things, many loose hammers.
    The design has both butt plates holding the hammers on, and a regular screw holding the flange on. While both needed tightening, I've found that the flange screws just won't stay tight. After tightening everything at the shop, I still had to do a round of tightening in the customer's home. What's loose isn't a mystery: you can see the entire flange wiggling back and forth. It's not the bushings.

    The thing is, those flange screws are tight to begin with. To get the flange to not move, I had to really crank them down. Anyone have any theories as to why hammer flange screws would tend to loosen up? Any fixes? The only thought I had was to take off all the hammers and install sand paper, as is common on grands. Any other suggestions? Even when I do crank them down and get them tighter, they need very little encouragement to develop some play again.

    thanks

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    Scott Cole, RPT
    rvpianotuner.com
    Talent, OR
    (541-601-9033
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  • 2.  RE: flange screws that won't stay tight

    Posted 11-12-2018 20:37
    You should consider installing washers between the screw and the flange; the problem may simply be that the flange's wood has shrunk over the years.

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    Patrick Draine
    Billerica MA
    978-663-9690
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  • 3.  RE: flange screws that won't stay tight

    Posted 11-12-2018 21:47
    The screw holes might be too shallow and the screw is bottoming out due to the reduced size of the dried flange. Larger and/or slightly larger screws may help.

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    Regards,

    Jon Page
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  • 4.  RE: flange screws that won't stay tight

    Posted 11-13-2018 01:24
    Jon and Patrick,
    Thanks for the suggestions. I may add washers next time I see the piano if anything has loosened up. If that doesn't work I may try larger screws.
    Scott

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    Scott Cole, RPT
    rvpianotuner.com
    Talent, OR
    (541-601-9033
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  • 5.  RE: flange screws that won't stay tight

    Posted 11-13-2018 07:16
    If the screws do not over-turn, larger screws may not be applicable, considering the size of the flange hole. Screw length might or drill deeper. Getting screws into vertical's hammer flanges is challenging enough without adding washers, I wouldn't want to do that.

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    Regards,

    Jon Page
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  • 6.  RE: flange screws that won't stay tight

    Posted 11-13-2018 09:19
    Put a tiny sliver of wood in the hole along side the screw to shim it.

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    Melanie Brooks
    Brooks, Ltd. Piano Products LLC
    Uncasville CT
    860-848-6605
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  • 7.  RE: flange screws that won't stay tight

    Posted 11-13-2018 10:38
    Scott,
    Humidity cycling changes the dimensions of wood components, resulting in loosening screws.  When RH increases, the wood expands and is *crushed* in proximity to the screw threads.  The damage to wood is not reversible.  Retightening the screws works until the next extreme RH cycle.
    Look for weather pattern cycles (warm rains to first frost here in Oregon/Washington), or the local environment (does the customer have a wood stove?).  There is no fix for loosening screws if the RH% swings 50 points.

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    John Rhodes
    Vancouver WA
    360-721-0728
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  • 8.  RE: flange screws that won't stay tight

    Posted 11-13-2018 11:05
    Hi Scott

    I like Melanie's response.  Get a box of round tooth picks.  The flat ones tend to disintegrate and not work as well.

    One method that sounds about safe as can be is to remove all the hammers, flange included.  Lay the action down so the hammer flange holes are now vertical.  Mix a bit of water with Titebond so it's a bit on the watery side.  The consistency of heavy cream comes to mind.  Shim each hole with a glue dipped (remove excess), premeasured length of tooth pick.  Shoe pegs I think are too big.  You don't need the strength of the glue, just a slight holding power to keep the shim from leaving the hole when the screw is removed.  Additionally, the watered down glue won't hold on to the screw as well once it sets.  Let the moisture in the glue penetrate the inside of the hole for a while before reinstalling the screw.  You'll want to catch that moment when the glue isn't hard yet but isn't fresh either.  Oozing is your enemy on this job.

    Make sure you don't get any on the surface between the flange and the flange rail.   Seriously, it doesn't take but a hint of glue.  Too much and you'll have ooze clamping and gluing the flange to the rail quite effectively. This method has some hazards so be very careful.  Doing this without any glue of some kind makes for a nightmare should the flange have to be removed later when the small shim falls out during removal or reinstallation.  It's a dark and crowded space in there.

    When you factor in the amount of time it takes to go back and deal with an ineffective repair, it's worth it to do the job right in the shop FIRST!!

    I got to wonder why these screws won't stay tight.  Are the damper screws staying tight?  Is there a metal component inside the hammer rail keeping the screw from digging in deeper?  It's wood, it's a wood screw, it should dig in deeper ...... or are all the holes wallowed out from previous tightening?  Is so, add a toothpick.  It makes the hole smaller.  Using a larger screw I would expect has the possibility that the screw won't fit in the flange hole.

    Adding a washer keeps the screw from reaching the full extent of it's reach.  When it loosens up you'll have a "tick" and a "clink" to deal with.  This won't do anything but use up LOTS of time.  Adding a longer screw may create problems with screw head size  .........  lack of clearance from the tip of the jack.

    Adding sandpaper reduces the depth the screw has to work with.

    My two cents.  Your turn.

    Lar

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    Larry Fisher
    Owner, Chief Grunt, Head Hosehead
    Vancouver WA
    360-256-2999
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  • 9.  RE: flange screws that won't stay tight

    Posted 11-14-2018 06:35
    One problem with wood shims is that the threading tends to chop them into little pieces. Shim a hole with leather or suede to have it conform to the threading and not be chopped up. Measure the depth of the hole to see if they need to bee a little deeper. But as mentioned, RH swings can cause this. Have you considered a DC to maintain an interior micro climate?

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    Regards,

    Jon Page
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  • 10.  RE: flange screws that won't stay tight

    Posted 11-14-2018 11:17
    Thanks all, some interesting answers.

    Jon, I'll suggest a DC unit it to the customer, but I'm not sure how much more he wants to spend on it, especially since it just came out of the shop. I suppose it depends how much trouble those flanges give me, and how many more loosen until the next tuning. Troublesome flanges are marked, so have a reference to see if they loosen yet again.

    Perhaps there's something to do with the area of contact between the flange and the rail? Maybe there's just enough warpage from time and rH changes so that the entire surface area of the flange is not quite making contact until it's warped by tightening the screw?

    This is a long shot, but it made me wonder: is the pitch of those 100-year-old screws steeper? Could this be cause them to go from very tight to loose in a very short turn? Would a modern screw with a different pitch help? That would imply some drilling of flanges and rail.

    Scott

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    Scott Cole, RPT
    rvpianotuner.com
    Talent, OR
    (541-601-9033
    ------------------------------



  • 11.  RE: flange screws that won't stay tight

    Posted 11-14-2018 14:39
    Edited by Peter Grey 11-14-2018 15:46
    Scott,

    As a diagnostic procedure I would install a washer AND a lock washer on the troublesome ones and monitor the difference (if any). This will:

    1) Tell you if bottoming out actually is the problem or not

    2) Apply a friction reducer at the point of screw contact, hopefully eliminating any tendency for the flange to turn slightly upon full tightening

    3) Apply consistent extra pressure with the lock washer AND enlarge the surface area of pressure on the flange.

    If this solves the problem, you know what to do. If it does not, you haven't spent too much time on it and can try another suggestion.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 12.  RE: flange screws that won't stay tight

    Posted 11-14-2018 17:54
    A double washer might cause the screw head to hit the jack on return. Or is it the jack hits the screw head. screwing vertical flanges is tough enough without adding washers.

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    Regards,

    Jon Page
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  • 13.  RE: flange screws that won't stay tight

    Posted 11-15-2018 18:16
    Interesting solutions for dealing with screws that won't stay tight.

    Under "quick and dirty" I have done the toothpick (or equivalent) concept. It often helps. But, toothpicks are not made of maple -- or whatever else the rail may be made of.

    Leather in my experience isn't necessarily any better. Again "it works, sorta, usually". And it's more involved.

    Another quick and dirty approach that I prefer to toothpick and the like is to poke a length of copper wire in the hole -- either from a piece of #12 lying around or the surplus I keep from bass string sets where the loops are tied with copper.

    If I were really going to "do it right" and go to the extent of removing a set of flanges, I'd plug and re-drill -- probably with falconwood or delignit material (remember that a dowel cannot be a plug because the grain is not oriented correctly).  ​This would be a truly permanent repair.

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    Keith Akins
    Akins Pianocraft
    Menominee MI
    715-775-0022
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  • 14.  RE: flange screws that won't stay tight

    Posted 11-15-2018 02:48
    I worked on a Bluthner grand a few years ago, it is about 110 years old, and the wood around the flange holes had turned soft and pulpy. I was able to drill some holes perpendicular to the flange screw holes and insert dowels so I would have some fresh wood to screw into. It was an area of 3 or 4 inches, maybe 5 or 6 flanges. The inside (whippen side) of the rail was actually easy to access without taking the whole thing apart. Not sure if something like this could be done on an upright rail without running afoul of the other action screws etc.
    That said, I've noticed on a few threads recently that we kill ourselves trying to come up with a low cost solution to what are actually pretty catastrophic problems, if not total write-offs. Sometimes the owners have to reconcile costly remanufacturing of parts like action rails or giving up on an instrument. In this case with Scott's piano, at least being willing to pay for removal of all the action parts so the problem isn't addressed piecemeal. Of course removing and reinstalling all the parts on a really old action could lead to many other problems which takes me to my next point.
    When I started, pianos built during the "golden age" were a mere 50-70 years old or so and generally reparable, now they are pushing 100 or over and in some cases parts just start disintegrating. There are some half-way measures I won't take anymore as I don't feel I'm doing the client or myself any favors.

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    Steven Rosenthal
    Honolulu HI

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  • 15.  RE: flange screws that won't stay tight

    Posted 11-15-2018 10:16
    So in cases like these--old pianos, changes in wood dimensions over years of rH changes--does a DC installation really help? Or is that barn door closed?

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    Scott Cole, RPT
    rvpianotuner.com
    Talent, OR
    (541-601-9033
    ------------------------------



  • 16.  RE: flange screws that won't stay tight

    Posted 11-15-2018 11:00
    "...and the wood around the flange holes had turned soft and pulpy."  Steven's phrase reminds me that failures like Steven and Scott describe are often confined to a half-dozen or so holes.  The likely cause is not faulty wood from the factory; it is a progression of failures which starts with screws that have been torqued down to the point that the wood at the threads is on the threshold of failure (crushing).  When this is followed by an extreme RH cycle, a portion of the wood at the threads compresses to failure -- and the flange loosens on the next half of the RH cycle.  At this point, the technician reefs *even harder* on the recalcitrant screws, and another cycle (RH and crushing failure) begins.  The result is the "soft and pulpy" wood which will no longer hold a screw.
    Steven is spot-on in his conclusion that long-term fix requires a proper repair, not half-way measures.  And I'll add that this includes obtaining reasonable control of the humidity.


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    John Rhodes
    Vancouver WA
    360-721-0728
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  • 17.  RE: flange screws that won't stay tight

    Posted 11-15-2018 21:07
    You could also try putting a drop of thin CA glue in the hole and letting it harden, hopefully stiffening the wood and making it less hygroscopic.

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    Ed Sutton
    ed440@me.com
    (980) 254-7413
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  • 18.  RE: flange screws that won't stay tight

    Posted 11-15-2018 21:39
    Speaking of CA glue, another effective repair with a high success rate for stripped screw holes is to stuff some paper towel in the hole, apply some Thin CA, coat the screw with McLube, screw it in, and unscrew it. Learned about this technique right here on this list some years ago.

    That said, nothing compares with the surety of a Falconwood or Delignit plug, as Keith has pointed out.

    Alan

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    Alan Eder, RPT
    Herb Alpert School of Music
    California Institute of the Arts
    Valencia, CA
    661.904.6483
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  • 19.  RE: flange screws that won't stay tight

    Posted 11-16-2018 09:37
    Many many people have been brainwashed into thinking that their piano should still be working at 100 years old.  Considering the fact that they were designed and built with the intention of lasting about 30 years (which is basically a generation), it's amazing they actually do operate AT ALL.

    Once the owner is clued in to REALITY on this subject, I have found that they are more likely to accept this reality and either restore or replace. They realize they were duped into thinking that it was supposed to last 100 years. Sorry, but it ain't the truth...I don't care WHO made it.

    What does this have to do with a screw in a hole? Probably nothing but I just had a cup of coffee and I'm ranting.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 20.  RE: flange screws that won't stay tight

    Posted 11-17-2018 10:16
    Peter,
    You're probably right. However, in my neck of the woods, I try to convince customers with old worn-out pianos to get rid of them and upgrade to....
    30-year-old pianos.
    Scott

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    Scott Cole, RPT
    rvpianotuner.com
    Talent, OR
    (541-601-9033
    ------------------------------