The “HT250” series testers are intended for reference force testing. Although they are
very repeatable and dependable, there is no specified tolerance on the force applied by
the tool.
The tolerance span of the tool is based on the accuracy of the calibration device and
method used to calibrate the tester. When the testers are manufactured by DMC they
The tester is clamped into the fixture (with the adjustment locking nut loosened or
removed), and the threaded compression rod is rotated until the center of the indicator
line is aligned with the sliding cover. The adjustment screw is then rotated until the
desired force is indicated on the calibrated force gauge that is part of the fixture. The
retention tester is then removed from the fixture and exercised a few times by
compressing the spring in the tester and relaxing it. The retention tester is then
reinstalled in the fixture. The setting process is repeated. If the desired force is shown
on the calibrated force gauge when the sliding cover is aligned with the center of the
indicator line, the adjustment is locked into place by rotating the jam nut, and binding the
adjustment screw on the top of the retention tester. The handle is replaced to conceal
the adjustment screw and lock nut.