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Reply to "Calibration Course"

This is a gizmo to make tape pulling with a DeLiar convenient.

Then, tried an experiment.: The “zero” end of a 200’ CST Berger 82-20010 B tape was nailed to the pavement of a walking trail. Then the tape was stretched out 200’ and allowed to relax.  An alcohol thermometer was set out in the shade of the tool.  Then a piece of masking tape was marked with a line at the 200.000’ point of the tape.  First, the tape was stretched using one hand “calibrated feel” tightness and a dot was put on the tape at that point.  It was awkward both holding the tape with one hand and marking with the other.   Next, pull forces of 5, 10, 15, 20 and 25 pounds were applied using the De-Liar which is over 50 years old.  A dot was made at each point.  A temperature of 83 F was noted at about 8:05 pm.

A passer-by asked if I needed any help so the experiment was repeated but this time two hand pulling was possible.  A second piece of tape was put down right next to the first tape and the 200’ point marked.  It was noted that the 200’ relaxed point was not even .005’ past the first set of measurements.  I pulled and she marked the particular pull points.

This is a table of results:

A few days later, I tested the 50 year old Deliar against a 20 lb dumbell and got only 18.5 lb.  That means 20.0 lb indicated was really 21.5 lb applied.  AND that the calibrated hand applying 20 lb force was almost dead on what it should have been.

Oscar

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