When testing Rockwell hardness, we use a apporiate indenter and the load required for testing to our scale. A chart can be found below showing the required combinations. When testing Rockwell hardness we first preload the indenter on our part, generally Rockwell testing machines have a scale that can be read, which has a smaller scale that will rotate to the 12 o'clock position showing a "SET" position, as our scale reading dial goes to a "0" or "SET" position as well. Once that position is achieved, our minor load of 10Kgf is set. Then one may release the lever to use the Major load, to get the combined total load on the part, which will plunge the indenter down into the part so we can get our baseline measurement on the Rockwell test.
Once the indenter stops entering the work piece, we pull back on the lever resetting it to the original position so we may get the actual loading point of the part. This is done by reinserting our indentor, with the lever which will reinsert it using our minor load, and then we can read the reading of the indicating dial for our hardness measurement.
The weights at the back of the machine are the major load, and must be set to the following table. Do not worry about the weights listed, this is the weight not the mass of the loading blocks. Which means that our 50kg weight is actually only 2kg in mass. As weight is mass times gravity. If your on Earth or the Moon, your mass remains the same, but your weight changes. No need to break out the overhead crane or other devices to aid in lifting the weights for the scale!
Ra . . . . Cemented carbides, thin steel and shallow case hardened steel
Rb . . . . Copper alloys, soft steels, aluminium alloys, malleable irons, etc.
Rc . . . . Steel, hard cast irons, case hardened steel and other materials harder than 100 HRB
Rd . . . . Thin steel and medium case hardened steel and pearlitic malleable iron
Re . . . . Cast iron, aluminium and magnesium alloys, bearing metals
Rf . . . . Annealed copper alloys, thin soft sheet metals
Rg . . . . Phosphor bronze, beryllium copper, malleable irons HRH . . . . Aluminium, zinc, lead
Rk . . . . \\
Rl . . . . ..||
Rm . . . . ||
Rp . . . .. || Soft bearing metals, plastics and other very soft materials
Rr . . .. . ||
Rs . . . .. ||
Rv . . . . //
One must remember that the National Institute of Standards and Technology only calibrates and certifies Rockwell C scale samples, therefor the other scales may vary depending on manufacturing standards of each manufacturer and may not always agree with each other like the Rockwell C scale will when using traceable equipment and hardness testing blocks.
I will add a additional page showing the tester being used so you can see how its done. Perhaps even a vedio will be added instead at a later date.