[pianotech] Piano "Gross Anatomy"

[Greg Graham]

If you didn't have to worry about hurting the piano, what "stress tests" would you want to try?

Have you always wondered how the frame of an upright is joined?

What does the back of a plate look like?  Will it break if you remove the plate screws under tension?


I’m working on ideas for a chapter "Gross Anatomy" dissection of a dead upright piano.  Rather than just pushing it out the second floor window like they do on YouTube, this would be a serious, planned series of experiments.  We would get to see how pianos are put together, test things to destruction, take home sample parts, etc.  Old hat for rebuilders, perhaps, but valuable experience for techs who don't usually tear 'em down that far.  

Heck, even rebuilders may want to "test to destruction" certain components that they usually need to save.

I'm hoping you can help me think through the experimental sequence below. 

I have a big old upright, but plan to check with local stores and to see if they plan on transporting any smaller, perhaps more modern pianos to the dump.  It may as well go to us and save the dumping fee.  I will recycle most of the case parts, action, and plate.  Other junk will go in my dumpster.

Ideas for "Piano Gross Anatomy" experiments: (Please suggest additional ideas!)

1.  Put CA glue on tuning pins that are loose.  Check penetration later when plate is removed.  

2.  Voicing related:
     a.  Revival of tubby bass string using the twist, loop, loosen-and-whack methods.
     b.  Shave hammer shanks in treble to hear tone differences.  Test for shaved-shank breakage on hard blows.
     c.  Over-file hammers, making them too light, too pointy, too flat, crooked crown, etc. 
     d.  Over-needle some hammers.  Over-lacquer some.  Over-steam some.  Iron some.  Over-iron some.

3.  String Termination Tests:
     a.  Put CA glue on the bridge and listen to false beats.  Better?  Worse?  How much is too much?
     b.  Pound in bridge pins.  Listen. Pound more.  Alot.  Too much.  
     c.  Over-seat strings at bridge, intentionally causing damage to bridge surface.  Beats?  How much is too much?
     d.  Downbearing modifications?  Shim under strings?  Chop away some of the bridge? 

4.  How far over pitch can old piano strings go before breaking?  
    a.  Test in several octaves.  
    b.  Test using smooth pull vs jerk hammer technique
    c.  How hard can you press on  a string with a pizza-wheel style string stretcher?   How hard can you whack it with a screwdriver at the v-bar?
    d.  Try ProLube at bearings to see if it makes any difference

5.  Structural tests:  
     a.  Jack the soundboard from the back frame and test for pitch change.  How much impact does the rise and fall of the soundboard have on pitch?  
     b.  Remove sections of soundboard, or ribs, or just separate from rim to see how tone changes.
     c.  Remove a couple back posts.
     d.  Remove several (most? all?) plate screws.
     e.  Whack the plate with a sledge hammer.

6.  Dissassembly as if for rebuilding.  
     a.  Remove keyframe, keydesk, legs, toeblocks, bottom board.
     b.  Break off sides.
     c.  Remove strings quickly, using becket breaker and/or power drill motor, and/or metal cutting angle grinder.  
     d.  Remove plate.
     e.  Test bond of pinblock to frame.  
     f.  Check penetration of CA glue on tuning pins.

This could easily go on for several meetings, but I think much of it could be done in one session (short business, long technical) if I pre-prep the piano.  I would remove loose case parts and hardware, remove keyframe screws, apply lacquer to hammers (so it can dry), steam hammers, apply CA to pinblock and bridge.  Gather tools, cameras.  Bring zip-lock baggies for small parts “party favors” for participants.  Prepare follow-up report for PianoTech list.

What else?

Greg Graham