ALTANA Hoffman Scratch Hardness Tester Manual - Manual (Page 5)

4
Calibration Procedure
Calibration Procedure
Place the Hoffman Scratch Tester on a flat, level
surface with the wheels of the roller carriage
contacting the surface and the scale arm
positioned to the left. The scale arm has no riders
attached.
1. Using the small allen wrench, loosen the
counter weight until it slides across the scale
arm.
2. The correct position for the counter weight is
when the scratching tool is in contact with
the surface with virtually no downward force.
A recommended starting position is the scale
arm protruding one or two millimeters to the
right of the counter weight. Adjust the position
of the counter weight on the scale arm and
tighten with the allen wrench.
3. Use the following procedure to check the
calibration:
• With one hand, hold down the roller carriage
so all the wheels remain in contact with the
surface.
• With the other hand, place one finger at the
very end of the scale arm and push down until
the scratching tool contacts the surface
(position 1).
• Remembering to keep downward pressure
on the roller carriage, slowly lift your finger off
the scale arm. The scale arm should stay in
position 1.