Pianotech

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

    Registered Piano Technician
    Posted an hour 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 an hour 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 58 minutes 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 10 minutes 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.