The American Weigh Digital scale models appear to be very practical for a
number of different uses, and not especially expensive for their stated
accuracies.
For a different approach, 3-point surface-contact tension gages are used in
a wide variety of applications, one particularly sensitive one is a tension
gage for VRC tape during Play mode as a way to see if the brake bands/pads
on the reels were set properly.
The running tape would be slipped between slender fingers on the gage.. how
far the center finger was moved/deflected indicated the tape tension on a
dial indicator or similar gage face.
Tentel was one brand of tape tension gages for VHS/Beta 1/2" machines, Sony
and other manufacturers had similar devices for professional 3/4" tape
machines.
I have a 3-point contact device for measuring lens surface curvature which
works similarly to a tension gage, but the 3 points are all on one side of
the lens and indicates the focal length on a small dial indicator-type gage
face (zero is checked on an optical flat).
There is a conversion chart included for 2 different types of lens
materials.. forget what they are now, haven't used it for so long.
Perhaps a similar 3-point jig could be custom made to utilize a digital dial
indicator with an output signal connector (SPI?) for attaching a signal
cable to a remote DRO unit.
I'm guessing that the (maybe bar of steel) "tension element" could have
eyelets or other hardware attachment features to allow it to be used for
numerous applications.. (something like using a current shunt with a DMM
discussed about a week ago).
I'm fairly certain that some of the engineering-types here could figure out
an adjustable or adaptable 3-point model which would utilize separate sets
of pads/blocks to be installed for different applications (band saw blade,
1/4" wire rope, etc) for one tester, a sorta universal tension tester.
--
WB
..........
"Jim Wilkins" wrote in message
...
"RogerN" wrote in message
So far I'm leaning toward something like this:
http://www.amazon.com/gp/product/B00...A1DVPD9Q368DLM
I figure I can make a link with the same dimensions hole to hole as the
scale. This way I can use the scale to tension the lines, mark the
turnbuckles, loosen, replace scale with metal link, and adjust
turnbuckles to bring the tension back. I figure the scale will stretch a
little under the tension, if needed I can measure scale hole to hole with
170 lbs tension. I like that design of scale because I should be able to
use couplers with pins that will fit the scale....
RogerN
Good catch! It looks considerably more compact and durable than the
discontinued HF 440 Lb Big Game Scale.
You could make a simple comparison gauge that measures cable deflection
between pins with a fishing scale and tighten the turnbuckle to the same
reading. It would be like checking engine belt tension by thumb pressure
deflection or how far it will twist, unable to measure the force but
adequate to set it close enough to the correct value.
In practice I've found that the forces I want to measure around the house
range from 500 Lbs to a max of ~3000 Lbs, for logging and pulling stumps.
It's difficult to apply more than 3000 Lbs with equipment made from lumber
yard and hardware store materials and I can buy higher-rated chains and
tow straps or call a wrecker for stuck vehicles.
3000 to 3500 lbs seems to be enough to move the base of a large (24") oak
that caught in another one as it fell. I've pulled down two that blew down
during storms behind neighbor's houses. Both were straight enough to saw
into lumber so I pulled them down intact.
jsw