The Model BB-75 Tester was developed to answer the need of certain industries for a method of rapidly testing the hardness of electro-deposited copper in the low hardness range. The B-75 penetrator is used to give sensitivity, and the Model B load spring is employed to give light pressures. This combination allows the user to test the soft range of many common materials.
The graph below shows the range covered by the Model BB-75 tester on copper. Results were derived from many samples, and show the average curve. All tests were conducted with the Model BB-75 Tester set to read 17 on a standard test strip of 6061-T6 aluminum alloy of Rockwell E 90± 1 hardness