[pianotech] SnS rim screws

[Joe Goss]

Sorry for the confusion. We Tightened only the plate bolts.
None of the nose.
My question about the nose bolts stems from earlier discussions on how the board flexes while the tension is let down
Thanks for the responses.

Joe Goss BSMusEd MMusEd RPT
imatunr at srvinet.com
www.mothergoosetools.com
  ----- Original Message ----- 
  From: Ed Foote 
  To: pianotech at ptg.org 
  Sent: Saturday, July 02, 2011 7:01 PM
  Subject: Re: [pianotech] SnS rim screws


  Joe writes:  
  >>I remember tightening the plate bolts ( or trying )  with a
  small 6 inch crescent wrench.  All bolts would not budge, so I thought every thing was fine. 
   Cut to the chase:
  We tightened the bolts  with a socket. Crown is back in the mid section where it was flat.
  Sustain 8 seconds!
   Quick questions
  The bolts are a 3/4" head and the low bass 1/16" larger
  How tight can I go.
   Can the tenor and treble nose bolts be adjusted up to gain more crown? They are the style that has a tuning hammer shape. The bass has a cover cap


  Greetings, 
      First, you mention plate bolts, then seem to refer to the nose bolts, while including "all" bolts.  The rim bolts should not change the crown, so I am assuming you are lowering the nose bolts.  I am sure you are aware that you are just bending the plate downward. How tight can you go?  Until you hear a crack and have broken the plate.  Without having installed the plate, and knowing what the preloaded flex is on the plate, I would be very leery of pulling it down with the nose bolts/caps.  The bass, with a cover cap, will not get you much gain in terms of bearing, and I would advise against changing it.  
      There are things I have done to analyze a plate under tension, like putting a dial indicator on the plate, and begin carefully undoing the large nut on a nearby nose bolt.  If nothing changes, the plate is either neutral or being held up by the bolt.  Loosen the other nut and see if it stays the same.  You may find that the plate is stressed upwards, held up by the shoulders on the nose bolts. I would be more serene lowering a plate such as that, than wanting to lower one that rises as soon as the nuts are loosened.  
     There is an amazing amount of flex that can be had on most plates, but not knowing where the starting point is is like running in the dark.  
  Regards, 


  Ed Foote 
    
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