Suggested Scale: 15N-Scale - 15Kg N "Brale"
Instructions:15N-Scale. Use the Superficial Rockwell Hardness Tester with a 15 kg. load, the diamond point N-Brale penetrator and the steel anvil.

Some Do's and Don'ts
Based on our experience

NOTE - We believe in the use of Rockwell Hardness Testers in determining hardness values for the above flat cold rolled products, (in fact we have 7 of them in daily use). But, remember that these values are approximate and vary somewhat from one tester to another and from person to person.

• We do not recommend the attempt to substitute B-scale Testers for Superficial Testers or vice versa.
• We suggest frequent use of test blocks for accuracy (use good side of blocks only). Change steel balls often and record changes.
• Never use a diamond point penetrator and a diamond anvil together.
• Keep tester clean-in a warm dry room-frequently oil elevator screw with proper oil.
• Avoid locating tester where subject to noticeable floor vibration.
• Be gentle in tripping lever-let the machine do the work. This is an instrument, not a production machine.
• Use care in selecting samples. They should be quite flat and free from distortion resulting from careless hand shearing.
• Samples should never be bent by hand or otherwise prior to testing. This results in inaccuracies.
• Inspect steel anvils for penetration damage at each using. Inspect diamond point penetrator and diamond anvil at each using.
• Values resulting from double or multiple thickness testing are approximate only.

• Even for steel, Tensile Strength relation to hardness is inexact, unless determined for specific material.
  
• The 15N, 30N, 45N, and the 15T, 30T and 45T scales pertain to our "ROCKWELL" Superficial Hardness Testers which apply exceedingly light minor and major loads for very shallow indentations, as required for testing nitrided steel or thin sheet metal.
  
• All relative values on this card are averages of tests on various metals whose differences in coldworking and other properties prevent establishment of exact mathematical conversion. Hardness values here given were carefully determined in our own Standard Laboratory."
  
• Because conversions are not altogether reliable, the actual work of checking should be done on similar and identical testing machines - and to the same scale without conversions. The following listings, because of space limitations are confined to those products and tempers regularly stocked by us at PRECISION STEEL. As other metals and alloys are added, this list will be amended accordingly.
• Not all technicians would agree with our testing procedures, viz., with the scales prescribed for different conditions. However, these are the standards we have set up for ourselves and so used by us.
• Of greatest importance however, is IDENTICAL MACHINES - Coupled with IDENTICAL SCALES