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eganders
Posted: Tue Apr 08, 2008 8:51 am
Guest
How do you make a strain gauge device that measures the strain (change
in length) of a metal band by clamping the gauge device onto the metal
band. The gauge would be an analog bridge strain gauge that would
have to have pads that allow them to be clamped on the metal band, but
the material that the gauge device was made of would have to have
little effect on the total resistance to elongation of the band, since
the band strain vs. force is what is being measured.

I know I could glue a strain gauge on the band itself to do the
measurement, but I want to be able to mount and unmount the strain
gauge on different bands.

The actual thing I am measuring is the tension in a bandsaw blade. I
found I could buy a mechanical strain gauge to do the measurement, but
find that I can buy a used strain gauge meter for much less and if I
can make a gauge, I will have a strain gauge meter for use in other
applications. Also, I believe it could potentially be more accurate
also.

sci.engr.mech
Mechanical Magic
Posted: Tue Apr 08, 2008 1:42 pm
Guest
On Apr 8, 10:51 am, eganders <egand...@yahoo.com> wrote:
Quote:
How do you make a strain gauge device that measures the strain (change
in length) of a metal band by clamping the gauge device onto the metal
band. The gauge would be an analog bridge strain gauge that would
have to have pads that allow them to be clamped on the metal band, but
the material that the gauge device was made of would have to have
little effect on the total resistance to elongation of the band, since
the band strain vs. force is what is being measured.

I know I could glue a strain gauge on the band itself to do the
measurement, but I want to be able to mount and unmount the strain
gauge on different bands.

The actual thing I am measuring is the tension in a bandsaw blade. I
found I could buy a mechanical strain gauge to do the measurement, but
find that I can buy a used strain gauge meter for much less and if I
can make a gauge, I will have a strain gauge meter for use in other
applications. Also, I believe it could potentially be more accurate
also.

sci.engr.mech


A removable strain sensor is very easy to make.

A simple "C" shape made of light gauge metal, for your application
maybe .75" radius.
The strain gauge is placed midway between the two ends.
The tips of the "C" could be magnets, or sharp points, held in place
with clamps, or even storng rubber bands.

http://www.princeton.edu/~humcomp/sophlab/m&mgl_30.htm

Dave
Brian Whatcott
Posted: Tue Apr 08, 2008 7:05 pm
Guest
On Tue, 8 Apr 2008 11:51:33 -0700 (PDT), eganders <eganders@yahoo.com>
wrote:

Quote:
How do you make a strain gauge device that measures the strain (change
in length) of a metal band by clamping the gauge device onto the metal
band. The gauge would be an analog bridge strain gauge that would
have to have pads that allow them to be clamped on the metal band, but
the material that the gauge device was made of would have to have
little effect on the total resistance to elongation of the band, since
the band strain vs. force is what is being measured.

I know I could glue a strain gauge on the band itself to do the
measurement, but I want to be able to mount and unmount the strain
gauge on different bands.

The actual thing I am measuring is the tension in a bandsaw blade. I
found I could buy a mechanical strain gauge to do the measurement, but
find that I can buy a used strain gauge meter for much less and if I
can make a gauge, I will have a strain gauge meter for use in other
applications. Also, I believe it could potentially be more accurate
also.

sci.engr.mech

You could cement a rosette or similar strain gage to a thin aluminum
strip, and clamp the two ends to the steel bandsaw blade, making it as
tight as possible, I suppose.
It's not likely to give great results I don't think: still, if you
reclamped and tested a half dozen times, the differences you see
might wash out to some extent.

Brian Whatcott
Altus OK
BobK207
Posted: Tue Apr 08, 2008 7:46 pm
Guest
On Apr 8, 11:51 am, eganders <egand...@yahoo.com> wrote:
Quote:
How do you make a strain gauge device that measures the strain (change
in length) of a metal band by clamping the gauge device onto the metal
band.  The gauge would be an analog bridge strain gauge that would
have to have pads that allow them to be clamped on the metal band, but
the material that the gauge device was made of would have to have
little effect on the total resistance to elongation of the band, since
the band strain vs. force is what is being measured.

I know I could glue a strain gauge on the band itself to do the
measurement, but I want to be able to mount and unmount the strain
gauge on different bands.

The actual thing I am measuring is the tension in a bandsaw blade.  I
found I could buy a mechanical strain gauge to do the measurement, but
find that I can buy a used strain gauge meter for much less and if I
can make a gauge, I will have a strain gauge meter for use in other
applications.  Also, I believe it could potentially be more accurate
also.

sci.engr.mech

Sounds like you're attempting to make a clamp on strain gage based
extensometer.

Knife blade clamp on extensometers are pretty standard in the
material testing world.

I'd guess that clamp on extensometers exist for thin materials as
well.

Check out Tinius Olsen, MTS, Satec, Instron for an idea of what
exists.

Depending on how accurately you want to measure the tension, I'm sure
there are easier & cheaper ways.

cheers
Bob
 
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