Yamaha Hammer Spring Cord Repair..from the archives

[Dean May]

I just did my first Yamaha cord repair job using the method Jon posted from
the archives a couple of years ago. It went really well. Attached is a
picture of my son gluing down the second end. You can see all the cords
sticking up to his right with the first end glued down. 
 

Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802

 

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jon Page
Sent: Saturday, January 08, 2005 2:26 PM
To: Kentucky1248 at aol.com
Cc: pianotech at ptg.org
Subject: Yamaha Hammer Spring Cord Repair..from the archives


Yamaha Hammer Spring Cord Repair 

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

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

Solutions: 
  Replace hammer flanges 
  Replace cords 

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


Tools and Materials: 
  __flange, thin-bladed, and Phillips screwdrivers 
  __spray lube and spring hook (for damper springs) 
  __shimming chisel modified to clean flange slots, or other suitable tool
  __glue applicator (syringe) filled with Tightbond & damp rag 
  __action cradle 
  __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) 
  __razor 
  __forceps 

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. 

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