Regulating With Metrics

[Dean May]

A hearty amen. When going through engineering school we primarily used
metrics and even when I worked in design in industry.  It sure did make the
calculations easier. 

 

Here’s a rough chart for you:

 

1” = 25 mm (25.4)

3/4 = 19 (19.1)

1/2 = 13 (12.7)

1/4 = 6 (6.35)

1/8 = 3 (3.175)

1/16 = about 1.5 (1.6)

1/32 = about 1 (.8)

 

Dean

Dean May             cell 812.239.3359 

PianoRebuilders.com   812.235.5272 

Terre Haute IN  47802

 

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jurgen Goering
Sent: Monday, February 04, 2008 11:53 PM
To: pianotech at ptg.org
Subject: Re: Regulating Without Specs

 

At the risk of opening a large can of worms and an even larger debate, I
think this is perfect example of why going metric (like Dale Erwin
demonstrated) is such an elegant mode of transport through exercises such as
these. Mixing fractions with decimal inches may work in this prepped
example, but the numbers are hardly ever so fortuitous. I heartily suggest
to all technicians to immerse themselves in millimeters, stop converting to
inches, buy metric rulers, calipers and whatever other measuring tools they
need and discover the brilliant ease of working in that system.
ducking for cover...
Jurgen Goering


On Feb 4, 2008, at 19:20, pianotech-request at ptg.org wrote:

snip...
Let’s just say you want something typical like a 3/8” key dip, 1/8” letoff,
and .050” aftertouch.  (Later I’ll show the equations for solving for
different variables)   Given the 3/8” key dip (.375”) and the .050”
aftertouch, we subtract aftertouch from key dip and know then that we have
.325” of useable key dip to move the hammer.  How far will it move?  It will
move 5xs the amount of keydip.  5 x .325” = 1.625”.  But that’s not the
hammer blow distance, because we haven’t accounted for letoff.  If we want
1/8” (.125”) letoff, we need to ADD that to the hammer travel of 1.625”, so
the blow distance is then 1.75”, or 1 ¾”.
 ...snip...
OK, Lemme know whatcha think!


 
John Dorr, RPT 

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