consistent downbearing measurements

[David Skolnik]

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Joe -
Not sure why you think you'll be needing a flame suit.  A lawyer maybe.  <oi->

The "angle" of deflection is a hypothetical construct.  If the profile of 
the bridge surface was the peak of a triangle, you could speak of an 
"angle" of deflection, however, distortions in the bridge surface 
(curvature or string held to bridge contact by pins) can alter the angular 
perception of deflection.

Still, the challenge of accurately measuring and conveying  the nature of a 
particular piano's string deflection, including the bridge, is, to me, a 
separate question from how much or little there should be or how it does or 
doesn't affect the instrument's qualities.  The answer to the original 
question of the subject is to develop some finesse with the tool. Design 
modifications would certainly help.

David Skolnik


At 08:16 AM 6/3/2004 -0600, you wrote:
>My thinking is that the angle of deflection of the speaking length and the 
>hitch end, are more an indicator of down bearing than is the segment that 
>crosses the top of the bridge. Might be in error here as this sure in not 
>something that real experience has taught me <G>
>To me it is Plane Geometry, and I may be looking at it from the wrong Angle.
>Why did I not purchase one of those 'flame suits' when they were 
>available. Conrad!
>Joe Goss
><mailto:imatunr@srvinet.com>imatunr@srvinet.com
>www.mothergoosetools.com
>----- Original Message -----
>From: <mailto:davidskolnik@optonline.net>David Skolnik
>To: <mailto:pianotech@ptg.org>Pianotech
>Sent: Thursday, June 03, 2004 4:52 AM
>Subject: Re: consistent downbearing measurements
>
>Joe -
>Returning, for a moment, to the piano aspect of this issue, what's your 
>reason for bypassing the bridge?  You'd get your net, though, in the case 
>of a rounded bridge surface, you could get a false zero or negative 
>reading.  (I don't think you can get a false positive, at least, I can't 
>visualize it.) Also, you'd learn nothing about the individual front and 
>rear components.  That was part of my issue with John's method.  He seemed 
>to have little concern for other than the net bearing, and even on that, 
>he had some ideas I found somewhat troubling. Unfortunately, (or maybe 
>fortunately for me) he's no longer contributing to these lists, so that's 
>not an avenue to pursue.
>
>As for using a laser,  you'd STILL have to solve the stabilizing problem 
>Greg spoke of.  Maybe you could come up with a Rare Earth Universal Mount, 
>with which you could use a Lowell OR a Laser.  (LOLREUM!)  Are lasers 
>affected by magnetic fields?
>
>But mainly I'm interested with my first question...why no bridge?
>
>
>David Skolnik
>
>At 04:42 PM 6/2/2004 -0600, you wrote:
>>Humm,
>>why would not a laser set on the string pointing at the rim, first 
>>measurment on the speaking length and the second reading on the tail with 
>>the laser pointed at the same target.  Bypass the bridge all together.
>>Just thinkin,
>>Joe Goss
>><mailto:imatunr@srvinet.com>imatunr@srvinet.com
>>www.mothergoosetools.com
>>----- Original Message -----
>>From: <mailto:Erwinspiano@aol.com>Erwinspiano@aol.com
>>To: <mailto:pianotech@ptg.org>pianotech@ptg.org
>>Sent: Wednesday, June 02, 2004 3:53 PM
>>Subject: Re: consistent downbearing measurements
>>      Greg
>>    Some techs do not rebuild but only use them to see if there is any 
>> residual bearing left in the 90 year old almost flat or flat  board. 
>> Under those conditions it's difficult to tell anything with the gauge 
>> because of the bridge slope towards the rear & a sunken crown/bridge as 
>> well  One gets really funky ideas of whats there &  not there if you 
>> know what I mean.
>>  As to your useage , yes of course this what they're for. I wasn't 
>> looking for trick answers. It would be nice if the gauge were fashione 
>> from cast brass or iron for a more solid seat on the string.
>>   Dale
>>Dale,
>>         Uh, I'm not sure what type of an answer your looking for here 
>> but I'll take a stab at it. I'm needing to set plate height during the 
>> course of a rebuild and check for down bearing during the course of 
>> evaluating a piano. Isn't that what their for?
>>Greg
>>At 10:45 AM 6/1/2004, you wrote:
>>>In a message dated 6/1/2004 5:23:38 AM Pacific Standard Time, 
>>>gnewell@ameritech.net writes:
>>>Thanks Dale. I've been doing just that but I'm not happy with the 
>>>repeatability of measurements. There's just got to be a better way. Any 
>>>other gauges out there? I seem to remember a Journal article with a dial 
>>>gauge of some kind. Am I dreaming?
>>>Greg Newell
>>     Gregg

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