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Betcha can't fix, can't replace

  • 1.  Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 20 days ago


    This is from a small 1966 Wurlitzer grand #942320. The broken piece in my hand was attached to the back of the belly rail, and broke off at the point you see next to it, which was where it tried to do an almost 90 degree turn to go under the rail. It apparently managed to work as a spring for the sustain trapwork for 80 years, until metal fatigue caused the already heavily strained metal to break when the sustain pedal was used once too many times. 

    It's fixable if we can replicate the metal strip and replace it for the broken one. But the angle would have to be very precise, the right metal of the right thickness, capable of flexing just the right amount under just the right pressure. But the metal strip looks a lot like the spring used in upright pianos to hold the wooden connector, under tension, between the pedal and the dowel that rises up to the action for the sustain or una corda, for example.  Do you think it's the same part? But I certainly didn't find any place to obtain one. I may have had some cannibalized examples, but decided that I had been keeping too much junk. 

    Unless some of you have a practical idea, I'm inclined to tell the owner that it's the end of the line. What do you think? It obviously not that valuable.

    Paul Larudee, RPT 


  • 2.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 20 days ago
    I'd bring it to a machine shop or welding shop and ask them to duplicate it.  I don't think it would be terribly difficult for them.





  • 3.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 20 days ago
    My concern is that it has to end up with just the right tension to act as a spring for the sustain lever. I can't imagine that it would be possible to even determine the correct amount.





    Original Message


  • 4.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 20 days ago
    I've not found trapwork tension to be all that critical.  Ex. I've removed the return spring for customers who found the pedal too heavy, and everything still worked fine.  I've also replaced broken springs, but asked the customer if the pedal worked OK in the meantime and they said it was fine.
    Off a glance it's probably just mild steel.  Get something of similar thickness into the right shape and I bet it will work just fine.  (Heat will probably be needed to get it into that kind of bend, which is where a proper metal shop comes in.)
    Edit: Maybe spring steel? Again a metalworker could probably look at it and give a pretty good guess on what to use.  Also, if err on the side of being too weak, you could always add a coil or leaf spring to give it a bit more return force.


    Original Message
    My concern is that it has to end up with just the right tension to act as a spring for the sustain lever. I can't imagine that it would be possible to even determine the correct amount.







  • 5.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 20 days ago
    Thanks, Nathan. The curve in the steel is not the issue. The problem is that the broken piece is broken at the place where it forms a tight almost 90-degree angle, and if it's welded at an angle that's only slightly different from what it originally was, it will greatly affect the contact height with the pedal dowel, which is at the opposite end of the lever. Furthermore, the original angle has to be at least partially a guess, since I never saw it in its original state.




    Original Message


  • 6.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 20 days ago
    Yeah in that case I'd err on the side of something flexible (spring steel, maybe thinner than the original), so that the angle isn't so critical.  And then just add a leaf spring somewhere if it's too floppy?



    Original Message


  • 7.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 19 days ago
    Paul

    A good welding shop will know exactly what to do to get the right tension on the spring.



    Original Message


  • 8.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 19 days ago
    I guess I'm not explaining this well. The part is both a lever and a spring. It fastens to the belly rail on the back (vertical) surface of the rail. At the bottom of the belly rail, it makes a more or less 90 degree turn back under the rail and toward the front of the piano.  Then it immediately curves under itself to make the curve that you see in the photo. Next, it attaches to the wooden sustain lever, about ten inches long, also seen in the photo. 2/3 of the way along the lever, it has leather covering on top to support an unattached Pitman. Then, all the way at the end is the leather surface on the underside that makes contact with the top of the brass pedal dowel. When installed, the lever has to sit at a very critical angle relative to its anchor point on the belly rail. It has to intercept the pedal dowel so that it puts pressure on it, but not too much. Nor should it be floating above it. All of this depends on the angles of the bends in the steel anchor strip. A little bit one way or the other has a dramatic effect ten inches away from the bends. And the sharpest of the two bends is where it gave way after 60 years and I got the call. Prior to breaking, it rested on the end of the pedal dowel with enough pressure so that it pushed back enough on the sustain pedal to make it behave the way a sustain pedal should. How can I replicate that precise bend, with just enough pressure on the head of the sustain dowel (i.e. just the right angle at the first bend) to assure correct performance after the weld has been performed? Not obvious to me. Hope that makes sense, and thanks to you all.

    Paul 




    Original Message


  • 9.  RE: Betcha can't fix, can't replace

    Posted 19 days ago

    Suppose you replaced this with an ordinary L bracket screwed in place with rubber washers behind and below the bracket.

    Would you be able to induce enough flex to make it work?



    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------



  • 10.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 19 days ago

    I've used a modified #593 Schaaf trap spring. 


    Original Message


  • 11.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 19 days ago
    I guess I'm not explaining this well. The part is both a lever and a spring. It fastens to the belly rail on the back (vertical) surface of the rail. At the bottom of the belly rail, it makes a more or less 90 degree turn back under the rail and toward the front of the piano.  Then it immediately curves under itself to make the curve that you see in the photo. Next, it attaches to the wooden sustain lever, about ten inches long, also seen in the photo. 2/3 of the way along the lever, it has leather covering on top to support an unattached Pitman. Then, all the way at the end is the leather surface on the underside that makes contact with the top of the brass pedal dowel. When installed, the lever has to sit at a very critical angle relative to its anchor point on the belly rail. It has to intercept the pedal dowel so that it puts pressure on it, but not too much. Nor should it be floating above it. All of this depends on the angles of the bends in the steel anchor strip. A little bit one way or the other has a dramatic effect ten inches away from the bends. And the sharpest of the two bends is where it gave way after 60 years and I got the call. Prior to breaking, it rested on the end of the pedal dowel with enough pressure so that it pushed back enough on the sustain pedal to make it behave the way a sustain pedal should. How can I replicate that precise bend, with just enough pressure on the head of the sustain dowel (i.e. just the right angle at the first bend) to assure correct performance after the weld has been performed? Not obvious to me. Hope that makes sense, and thanks to you all.

    Paul 





    Original Message


  • 12.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 19 days ago

    Is there a similar sostenuto lever that you could replace it with?



    ------------------------------
    Larry Messerly, RPT
    Bringing Harmony to Homes
    www.lacrossepianotuning.com
    ljmesserly@gmail.com
    928-899-7292
    ------------------------------

    Original Message


  • 13.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 19 days ago
    Thanks, Larry. That's the first thing I checked, and unfortunately it's a completely different design. With the customer's authorization, I may just weld it and see if it can be bent to fit.




    Original Message


  • 14.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 18 days ago

    I seriously doubt that any weld would last more than one use.

    Take it to any good metal shop and have them make you a replacement.



    ------------------------------
    Blaine Hebert RPT
    Duarte CA
    (626) 390-0512
    ------------------------------

    Original Message


  • 15.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 18 days ago

    Yes, I guess that would make the most sense, although it's going to be hard to determine the correct angle of the broken part and the replication of the material, and I don't know how critical that will be. I'm expecting to have to bend it to a certain extent on site. I'll warn the customer that the result is uncertain and the estimate approximate. Thanks to you and everyone. 

    Paul 



    Original Message


  • 16.  RE: Betcha can't fix, can't replace

    Posted 18 days ago

    The unusual spring was designed to facilitate quick installation in the factory.

    If you forget about the broken spring and just think of the necessary movement of the lever to operate the system, it should be fairly easy to design a workable replacement using available hardware.



    ------------------------------
    Ed Sutton
    ed440@me.com
    (980) 254-7413
    ------------------------------

    Original Message


  • 17.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 18 days ago
    I figured that was the idea of the design, and designing a workable alternative is possible. But how much time is it going to take and how much am I going to charge for it? At my usual hourly rate, I can't imagine it being less than $1500. I suppose it's an easy way to get them to dump the piano. I love my work, but not enough to make this job more affordable. 




    Original Message


  • 18.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 18 days ago

    I would imagine that a metal shop could make one in less than an hour.



    ------------------------------
    Steven Rosenthal RPT
    Honolulu HI
    (808) 521-7129
    ------------------------------

    Original Message


  • 19.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 18 days ago
    Thanks, Steve. That's helpful. 





    Original Message


  • 20.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 17 days ago

    Paul,

    I agree with Ed. 

    A simple re-engineering might be to use a hardware store hinge and to place a coil or leaf spring somewhere to add the necessary resistance and return force. 



    ------------------------------
    Blaine Hebert RPT
    Duarte CA
    (626) 390-0512
    ------------------------------

    Original Message


  • 21.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 17 days ago
    I don't disagree, but between procurement of the parts, testing and adjusting the system, the time to accomplish it can get out of hand. I try to avoid jobs of unknown duration unless I estimate really high and then charge less if warranted. When I commit to a job, it gets done, but I really like to avoid surprises. 




    Original Message


  • 22.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 15 days ago

    Any fabricator or blacksmith should be able to duplicate this for ca $200.  Heating will enable the bend. Should outlast the piano.



    ------------------------------
    Parker Leigh RPT
    Winchester VA
    (540) 722-3865
    ------------------------------

    Original Message


  • 23.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 15 days ago

    Removing the shorter "leg" of a "pelican" spring can work mounted on the keybed rear edge if not the belly rail. A lever & vice readily adjusts the bend need be.


    Original Message


  • 24.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 15 days ago
    Makes sense





    Original Message


  • 25.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 13 days ago

    If you can do some 3d modeling or 2d drafting, try something like www.sendcutsend.com.  They can machine and bend metal pretty precisely, and for very reasonable prices.  Might be worth looking into.



    ------------------------------
    Tom Dowell
    Hulbert Piano
    tom@hulbertpiano.com
    262-221-0792
    ------------------------------



  • 26.  RE: Betcha can't fix, can't replace

    Registered Piano Technician
    Posted 13 days ago
    Thanks. I took it to a local yacht and merchant marine metal shop. The price is probably not as good, but no shipping. Good reference for next time.




    Original Message