Lowell Component Downbearing Gauge

[Jack Houweling]

Hi Dale,

Could you or anyone else give me the lengths of the three gauges posted below. I made one a while back but now realize that I need different lengths. Great gauge for your toolkit and easy to explain to a customer.

Jack Houweling

  ----- Original Message ----- 
  From: Erwinspiano at aol.com 
  To: pianotech at ptg.org 
  Sent: Friday, May 04, 2007 6:05 AM
  Subject: Re: Lowell Component Downbearing Gauge


   Hi Paul 
    I totally get that & I was unclear. If the rear segment is traveling downhill from the aliquot to the rear bridge pin because of bridge slope then trying to measure bearing like this can also be fraught with errors. Or you can take it under advisement &  keep a wary eye on the results. 
     Enclosed is a picture of a bearing gauge I posted before. With this jig even if the rear string angle travels down to the rear pin the net over all bearing can still be ascertained. I'm still fiddling with the information this gives but one thing is for sure, if there is real & residual bearing in the piano it is easily visible, to you & your clients.
  I.e. hold the gauge at the speaking length pins & rock downwards so the rear touches the aliquot.  If bearing is present then a gap will be evident between the aliquot & the bottom of the gauge.  On a 5 inch string segment yielding a gap of .065 thous (as measured with the gauge in the picture) reveals that there is about 3/4 of a degree of residual net bearing.  Now this is a new board set up at 1 1/2 degrees. SO I'v squashed the board 3/4 of a degree. 
    I like this because it's quicker than the Lowell & more visual.  It may not tell you everything but it tells a huge story quickly. JMHO
    Frank, you should like this as a quick visual of deflection.

   For accurate result the gauge must be held tightly against the pins on the front section while pivoting. I checked every piano in the rebuilders gallery in Rochester & all the pianos had significant bearing that was immediately obvious from the distance the gauge rocked. & some possessed more than 1 1/2 degrees. hmmm?
    Dale Erwin









    Dale:

    I'm not picturing what you're trying to describe. "The rear foot of the gauge"? Both feet of the gauge sit on the "duplex" segment when you're measuring it, just as both feet of the gauge sit on the speaking length when making that measurement. Are you suggesting that the "front foot" when measuring the backscale is on the bridge and the rear foot is off--on the backscale string? This would an incorrect use of the tool, and fraught with error. After zeroing out the gauge on the bridge top (now that's a measurement that's fraught with error as well; if anyone assumes that the bridge top is all in the same plane, then there's a big mistake being made), the gauge is moved wholly to the front scale in front of the front bridge pin for a measurement and then wholly to the back scale behind the rear bridge pin for measurement, and the two combined yield a "net" bearing. Am I misunderstanding you? As dull-witted as I am, it wouldn't surprise me.

    Paul






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