Vertical hammer return spring slings, replacement of

[TOM DRISCOLL]

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  Hi All,

    This Monday I will replace all of the hammer return spring slings on =
an older Yamaha U3.  Yamaha graciously provided the cord material.  =
Someone advised removing all of the dampers and leaving the hammers on =
for the operation.  However, looks to me like it would be rather tricky =
to get the glue and the right length of cord in the right place in the =
hammer flange slots with the hammers still on the rail.  My current plan =
is to leave the dampers, but remove all of the hammers so they may be =
handled individually.

    Anybody out there worked through this to their satisfaction?  Got a =
solvent that works better than alcohol for loosening up the old glue?  =
For installing the new cords, have you used CA, hide glue, =
what-have-you? =20

    Any and all input is welcome, all the more so if it is before Monday =
morning.

    Have a good weekend,

    Alan Eder, RPT
       =20
    Alan,
        This description from our friend Jon Page in=20
        much more detail than my post from the archives of some years =
back.
        Jon has chosen to omitt the use of acetone as a glue solvent in =
his step 9 but I find the acetone to virtually allow you to wipe the old =
cords from the slots  and have seen no deleterious effects on the flange =
bushings. JMHO.
        Tom Driscoll
       =20
       =20
    Yamaha Hammer Spring Cord Repair=20

    Problem:=20
      Hammer return spring cords have become fragile and are breaking.=20

    Symptoms:=20
      Cords have turned a brownish color.=20
      Random breakage is occuring.=20
      Touchweight is affected on some notes where the spring is =
contacting the damper lever.=20
      Hammer sometimes falls audibly into strings on slow release before =
being pulled back by bridle tape.=20

    Solutions:=20
      Replace hammer flanges=20
      Replace cords=20

    Condition of action:=20
      If condition of the hammers, pinning, and travelling/mating to =
strings is all good, replace cords.=20
      If pinning is poor then flange replacement may be a better option. =

      Beware of earlier type action without butt plates - the following =
method would not work in this case.

    Cord Replacement Procedure:=20
      1.    Place action in cradle; remove hammer rest rail and treble =
bracket.=20
      2.    Reverse action so that hammers and dampers are facing you.=20
      3.    Loosen hammer butt plate screws.=20
      4.    Remove hammer assemblies from flanges and let hang from =
bridle wires; keep them in order to avoid tangling.=20
      5.    Straighten any bent return springs.=20
      6.    Tighten all wippen flange screws.=20
      7.    Tilt action toward you 90=B0 so that the hammer flange cord =
slots face upward.=20
      8.    Tighten remaining flange screws.
      9.    Using specially adapted shimming chisel or other suitable =
tool, clean slots (no solvent) and vacuum up debris.=20
    10.    Wrap 90+ turns on dowel with new cord and cut turns with a =
razor.=20
    11.    Glue one end of each piece to one slot on each flange.=20
    12.    Return to first flange and glue the other ends to remaining =
slots; check with gauge.=20
    13.    Lubricate damper spring slots.=20
    14.    Replace hammers; tighten butt plate screws; hook springs =
under flange cords as you go.=20
    15.    Replace hammer rest rail bracket and reinstall rest rail.=20
    16.    Final check: jack springs engaged with jacks, spring cords in =
crook of hammer return springs, bridal tapes not twisted.=20


    Tools and Materials:=20
      __flange, thin-bladed, and Phillips screwdrivers=20
      __spray lube and spring hook (for damper springs)=20
      __shimming chisel modified to clean flange slots, or other =
suitable tool
      __glue applicator (syringe) filled with Tightbond & damp rag=20
      __action cradle=20
      __replacement cord, e.g., braided Dacron of suitable diameter =
(kite string, parachute cord) or silk cord (Pianotek)
      __9/16" dowel [turned down from 5/8" dowel] or suitable width =
piece of cardboard
      __blunted scriber (or use small screwdriver, to help place cords =
in slots)
      __gauge (dowel, sized to fit intact flange cord, with end rounded =
off, to check loop size)=20
      __razor=20
      __forceps=20

    Many different types of cord will work. White braided Dacron looks =
the best and will last forever. Joe Goss suggests Spider Wire which I've =
bought but haven't tried yet. It's a similar color to the stuff you're =
replacing so that tends to go against using it. I used to use squidding =
line but the kind you'll likely find in fishing supply places is =
waterproofed and wouldn't take well to Tightbond. Probably the easiest =
(and possibly cheapest) is to order the silk action cord from Pianotek =
($3.95 for a 30-yard roll).

    Cleaning out the slots is not critical and you could even give the =
flanges a quickie scrub and vacuum treatment and commence with step 10.=20

    This method is taken from Tom Driscoll who posted it to the list in =
May, 2002 (Yamaha Upright Hammer Flanges).=20
       =20

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