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Broken Pressure Bar Screws

  • 1.  Broken Pressure Bar Screws

    Posted 29 days ago
    I recently tuned this 1950s Hardman upright that has two broken pressure bar screws. One of them had broken, fallen out, and was caught under the keys, and the other looked "loose" but then turned out to be broken as well.  They're both broken right where the threads start on the screws and they were right next to each other in the pressure bar. See attached pics. There doesn't seem to be anything wrong with the pin block (that I can see). Any ideas what might have caused these screws to break? What's the best method for extracting and replacing the screws? This is certainly not a high level instrument, but the owner has just bought it in order to learn to play the piano and seems a bit proud of it, so I don't want to totally burst her bubble... If there's an easy fix I'd like to make it happen.

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    Andrea Hackbarth
    Corvine Piano Care
    Palmer AK
    907-435-7697
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  • 2.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    Edited by Ed Sutton 29 days ago
    Andrea-
    Is there a noticeable difference in the sound of the notes at the missing screws?
    If the sound is acceptable, leave it as it is. These screws may have been broken long ago.
    The usual method for removal is to drill a hole in the screw stub and extract it with an "easy out," but that is treacherous in this location, since the screw stubs are tightly imbedded in a hard pinblock.
    You could also try to drill down with a larger drill, hoping to grind away the screw stub, leaving a larger hole to be filled, then replace the screws. Maybe breaking a string in the process.
    Or maybe you can find a bolt that would thread into the cast iron hole in the plate...and it may strip out under the stress of being tightened...
    Or you could try to drill a new hole through the bar and plate, between the strings and into the block. A new round head screw or bolt would not need to be countersunk into the bar.
    And all of these repairs could add up to more than the piano is worth, so I hope it's acceptable to just leave it alone.

    But remembering your situation, maybe it's to your advantage to develop skills in repairs like this. Consider adding a new screw between the old screw holes. Get an appropriate round head machine screw and a tap and die set. Push the strings a little out of the way. Drill a hole through the pressure bar, large enough to clear the screw. Drill a smaller hole through the plate and well into the block, appropriate size to thread for the screw. Use the right tap to cut a thread into the plate and pinblock, put in the screw. If you're not familiar with these tools, practice first on scrap metal and hardwood. (Every pianotechnician should have a nice tap and die set.)

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    Ed Sutton
    ed440@me.com
    (980) 254-7413
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  • 3.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    Hi Andrea, it's hard to tell with the image but it almost looks like those might be nickel plated brass screws.  I highly doubt that but that's what I'm seeing and if so, that's probably why they're broken.

    Two things come to mind right away.  First, the removal of the remaining part would have to be done through the little hole in the pressure bar to be cost effective.  Secondly, the cost to do this repair, in actuality or in consequential expense, is time wasted  .......  in my opinion.

    Once you start, you own the repair and success is the only option.  Are you willing to accept this??

    If it's holding a tuning in that area, leave it alone.

    If not, let the tension down in the repair area, remove a couple of screws either side of the effected area and add a piece of stout metal to reinforce that area.  Do this only if the notes in that area can't hold a tuning.  Longer screws will most likely be needed and I'd personally go with hardened screws.  Once again, failure is not an option.  Thorough communication with the owner about this job is really important.

    Lar

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    Larry Fisher
    Owner, Chief Grunt, Head Hosehead
    Vancouver WA
    503-310-6965
    Working the gravy zone for the rest of my days.
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  • 4.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    Thank you Ed and Larry! I was worried that the fix might be rather complicate or dicey, and you've confirmed my suspicions. To answer some questions: Right now, the sound of those strings doesn't stick out as any different than the rest of the piano. I do have to go back next week to replace a broken bass string, so I'll check them again to see if they're holding the tuning. Larry, I think you might be right that they are nickel plated brass screws or something similar. Their unusual composition stuck out to me and the owner as well.

    At this point, unless those strings are out of tune or sounding funny when I go back next week, I'll recommend to the owner that we just leave it alone for now. But I'll also take your advice, Ed, to get myself a tap and die set and start practicing.

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    Andrea Hackbarth
    Palmer AK
    907-435-7697
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  • 5.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    Andrea,

    I would also recommend that you want the owners that under the current circumstances the surrounding screws are now taking an extra load and may not hold in the long run. They are under tremendous stress, and now that you know that brass was used rather than steel, it is a compromised situation that does have implications.

    It's the same idea as a broken wire in a unison. If not addressed, the risk of breakage on the remaining wire is greater, since now 1 or 2 wires are taking the impact intended for the original 3 wires.

    If a third screw breaks (no matter what) be prepared to condemn the piano as it will continue to accelerate in weakness. (I would warn them of this).

    I wonder if this is a reason with the piano was for sale?  Did this woman get a really good "buy" on it?  Just curious.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 6.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    Beginning of tread on the screw is sweet spot , or by other word concentrator of tension.
    Drill new hole in the bar , plate and pinblock next to neighboring unison and install new screw, hopefully better quality. Tread on screws in ancient time use to made by cutting( less tension) in contrary to rolling methods in our days( more tension) . Pianos before1910 usually have cutting thread.

    Alexander Brusilovsky




  • 7.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    Thanks for this, Peter. I'll definitely warn the owner. I'm guessing she didn't pay much for the piano to start with, but I would also guess that the previous owner didn't know about the broken screws either since it hadn't been serviced in some time. There are lots of "cheap" pianos around here for sale... many of them not worth the cost of transport...

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    Andrea Hackbarth
    Palmer AK
    907-435-7697
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  • 8.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    I just thought of another repair that's a bit easier and related to my other suggestion.  I've taken apart many pianos and saved the parts for what ever reason.  I have a pressure bar dangling from a nail in my shop somewhere.  If the screw holes were to line up you could cut a piece of this old pressure bar and piggy back it over the existing one using some longer screws in the neighboring positions.

    Additionally, reverting back to a previously mentioned repair, if the broken screws are brass they'll drill out easily  ....  compared to steel.  Start with a small drill bit first and work your way up.  Once it's gone, plug the hole with a dowel and some wood Epoxy.  Redrill the now plugged hole to the proper size for a replacement screw  ...  one made of steel this time eh?

    Lar

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    Larry Fisher
    Owner, Chief Grunt, Head Hosehead
    Vancouver WA
    503-310-6965
    Working the gravy zone for the rest of my days.
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  • 9.  RE: Broken Pressure Bar Screws

    Posted 29 days ago
    I agree with Larry.  We use a phrase with our guys here: "If you touch it, you own it."  Good judgement comes from experience, and a lot of that experience is bad judgement.  At least that's how it is for me!

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    Ted Rohde
    Central Illinois
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  • 10.  RE: Broken Pressure Bar Screws

    Posted 28 days ago
    Probably someone tightened up the screws and used too much torque  or they where defective screws that expanded and contracted enough that a hairline crack finally failed. In any event I think with the proper easy out extractors and powerful drill they could be removed , the hole cleaned up and new screws of the proper length and thread installed. You could also try the technique of using progressively larger drill bits to grind out all of the broken screw metal but you will need the proper drill bits for steel- not wood, eye protection and a good powerful drill plus good lighting . You have to get the drill as centered as possible on the old screw and keep the bit straight as possible lest you wander off and enlarge the screw hole. If it is beyond your ability , skills , confidence it may be better to defer to another technician. Of course there is also the cost and time it will take. Assuming your repair rate is something like $50 an hour and the repair takes two hours is the customer willing to pay $100 ? If she is just learning the repair may not really matter to her

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    James Kelly
    Pawleys Island SC
    843-325-4357
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  • 11.  RE: Broken Pressure Bar Screws

    Posted 28 days ago
    If it's decided to leave things as they are and hope for the best, then it might be a good idea to replace the screws on either side of the missing screws with stronger screws. But don't replace them both at once; one at a time.


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    Don Dalton
    Chester VT
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  • 12.  RE: Broken Pressure Bar Screws

    Posted 28 days ago
    Don, the only potential problem with that (though it is logical) is that if one of those screws breaks in the process of removal...fill in the blank. 😢

    Pwg

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