New Bearing gauges that don't lie

[Erwinspiano at aol.com]

Ron

It's an  old idea, and works very well if you don't need front 
and rear bearing  information. For setting up new boards, no 
problem, but I've seen field  diagnosis instances where pianos 
had negative front bearing and positive  net, and clanged on 
the bridge pins on a hard blow. A rocker gage didn't  indicate 
any problem, but the bubble gage showed it  clearly.
  I see your point. Perhaps this gauge then has it's most  useful in 
situation where there is still measurable positive bearing as long as  the front 
termination is the highest point in the bearing line. Or perhaps a gap  wouould 
appear under the front foot between the string & the bottom of the  foot 
indicating negative bearing here.  I'll have to  experiement.
  I  did start out using it as a verification gauge for  bearing on new 
boards.   In the scenario you describe then it would  appear that this would not 
give enough information.
  Isn't the condition you describe kind of rare though?  Usually old board 
are just negative period. Nevertheless I can see that the  bubble gauge has an 
advantage in this situation.
 I've observed in many old boards it's really kind of  difficult to tell what 
bearing exists even with the bubble gauge, not only  because of a sunken 
board  but the angle of the bridge top.
 IMO so much disinformation given using the Lowell gauge which  is either 
operator error or just limitations of the device itself as to question  it's 
usefulness in certain circumstances. I was hoping  for something  more reliable & 
simple.



I do have a question though. I use the above formula to set up  
initial plate height with a thread, and my deflection 
calculations,  but how do you use the sticks to set bearing 
before you have strings  on?
  I haven't used the sticks to do this nor am I sure  it can be done.
 I've always utilized a version of pre-stressing the board  before I cut my 
bridge height & this has worked very well so  far.  I think that this type of 
gauge may give very useful & accurrate  residual bearing information on newly 
set boards or on fairly new piano , on  which we assume there is crown & 
bearing. 
  Thanks for the feedback
  Dale



Ron N

 
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