wasted CA on grand pinblock

[Frank Emerson]

How do you know if there is a gap between the pinblock and the plate?  Tighten the pinblock screws.  If you find that they can be tightened even a little, the gap described in the original post probably did exist, before tightening the screws.  With about 20 tons of combined string tension pulling on the pins significantly above the top surface of the pinblock, the tension will pull the pinblock up to the plate at the stretch side of the block, and down, away from the plate at the plate flange side.  This is encouraged by the draft angle of the plate flange (about 7 degrees), matched by the angle of a well-fitted pinblock.  Even this slight angle of incline constitutes a ramp to further encourage movement in this direction.

I have no experience with CA treatment of pinblocks, but in light of the problem presented in the original post, I would suggest tightening and retightening all plate screws before CA treatment.

In designing new pianos, I position all pinblock screws that would otherwise be covered by strings, to be located in the spaces between unison string groups, so they will be accessible for tightening in the field.  Others in a company where I previously worked scoffed at my effort, saying, "Why bother.  Nobody tightens pinblock screws.  When you tuned pianos, did you ever tighten pinblock screws?"  My response was, "Yes!  Not every time I tuned a piano, but regularly on pianos that I maintained routinely."

I have also tried to get manufacturers, for whom I have worked, to add a machining operation to make the plate flange perpendicular, or better yet, with a reverse angle to the original draft angle.  Until now, all have been unwilling to add to the limited machine time on their CNC milling machines to include an "unnecessary" operation.  The company I am now working for has agreed to include this feature in my next design.  

This is a Chinese company, by the way.  The criticism of Asian pianos I read on this list and from others in America is well deserved, but I believe that you will very soon be pleasantly surprised with the quality you will soon see from China, at least from one company, if I have anything to do with it.  We expect to show my Hailun concert grand at the NAMM show in Jan.  I do not wish to reopen the can-of-worms about working conditions in China, but I can tell you that if you took away the jobs at Hailun Musical Instruments in Ningbo, the works in those jobs would be hard pressed to find as good a life style as they now enjoy with their current jobs.

Frank Emerson
pianoguru at earthlink.net


----- Original Message ----- 
From: William R. Monroe 
To: Pianotech List
Sent: 11/8/2006 6:23:17 PM 
Subject: Re: wasted CA on grand pinblock


As an addendum, Dave, how is it you know there is a gap between the block and the plate??  Without taking them apart, it would seem hard to tell.  Are you assuming that since CA leaked out one side that there is a gap?  If so, I'd caution against that assumption, and echo what both I and Dean wrote regarding quantity of CA and rate of application (little bit at a time).

Food for thought.

Regards,
William R. Monroe
 
    I  CA'd a grand pinblock yesterday, and it did tighten up the pins, but I don't think all that much CA got down the tuning pin holes.  There was a gap between the bottom of the plate and the top of the block, and the top surface was downhill toward the belly rail, so a good deal of my CA ran toward the back edge of the pinblock and dripped down onto the newspapers I had on the keybed.  What a waste!  The stuff ain't cheap.  
    But how could I have known in advance that the top of the pinblock wasn't level?  The top of the plate surrounding the tuning pins seemed level.  If I had known, I would've jacked up the rear leg a bit.  But how far?  If the plate above the pinblock isn't precisely a uniform thickness, you can't be sure.  
    Now I'm reluctant to CA again if there appears to be a noticeable gap between the plate and block (I suppose there's always some), for fear the CA will just run all over the top of the pinblock and not get down the holes.
    --David Nereson, RPT
    
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