Re: Re: Home-Built Beam Balance

From: <dgbj_at_aol.com>
Date: Sat, 9 Dec 2006 20:01:30 EST

LD,
 
This is very good. Thanks for sharing it with us. Having the pads glued to
the bar introduces a serious error. Because the pads are rigidly attached
to the bar, placement of the object to be weighed will influence the balance.
Placing the object close to the blade will show a lower weight than placing
it farther out. Try it. The pads must be suspended with a nonrigid
attachment from a point on the beam.
 
There are some refinements to consider.
 
Trim nut. Having a machine screw with a nut on it sticking out from the end
opposite the scale will allow fine trim of the balance by moving the nut
along the screw..
 
Vernier. A vernier is a small scale attached to the sliding weight that
allows reading one finer division of the scale. It has 10 divisions, but is
9/10 of the length of 10 scale divisions. If the index point on the vernier is
between two of the divisions on the scale, the subdivision corresponds to the
value where the vernier marks most closely approximates the corresponding
mark on the scale.
 
Damper. The oscillation of the beam can be slowed with a magnetic damper.
A damper consists of a thin aluminum plate attached to the end of the beam
and a strong magnet near by. As the aluminum plate moves through the magnetic
field an electric current is induced. The induced current opposes the
magnetic field and exerts a force on the aluminum that is opposite to the direction
of movement.
 
Gary Hinze


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Received on Sat Dec 09 2006 - 17:09:26 CET