ALTANA Hoffman Scratch Hardness Tester Manual - Manual (Page 7)

6
Operation
Before initial setup, please remove protective film
from the scale arm (balanced beam). In operation,
small and/or large riders are attached to this arm
at the numbered positions. These must be placed
on the scale very carefully so that the test surface
is not marred before actual testing is begun. The
large rider generates a load of 100 grams per
division, while the small rider generates a load of
25 grams per division. The small quarter rider may
be used for marking low range measurements
involving small increments of pressure, or it may
serve as a vernier in conjunction with the large
rider in making more precise medium range
measurements. Two large riders may be used
for making high range measurements. The sum
of all the rider settings represents the total load
in grams applied by the lever system to the
scratching tool. The scale arm is counterpoised
and its graduation marks can be used with any
combination of riders to create a reproducible load
on the pivoted lever system. In order to assist you
in selecting the correct rider for your application,
listed below are several examples:
• Small quarter rider at position
4: 4 x 25 = 100 grams
• Large standard rider at position
20: 20 x 100 = 2000 grams
• Large standard rider at position 6, plus small ...
quarter rider at 2: (6 x 100) + (2 x 25) =
600 + 50 = 650 grams
• Large standard rider at position 20, plus ..........
.............another large standard rider at position
10: (20 x 100) + (10 x 100) =
2000 + 1000 = 3000 grams
After attaching the rider(s), place the Hoffman
Scratch Tester on a flat test surface that measures
at least 2 x 4 inches (5.1 x 10.2 cm). Place your
Operation