We have been considering calibrating our own Rockwell hardness machines (testers). In the newest revision of ASTM E-18 (02 version); it discusses the process of verifying the force of the penetrating mechanism. It appears that we must simply use a measuring device to measure the force delivered at the different scale ranges. If anyone has any experience with this, please voice your opinion on the best practice going forward. I really need to know how to test the force for calibration purposes. I think I have a grasp on the remaining subjects in reference to calibrating hardness testers. I am not interested in an outside lab. We have so many machines and there are so few qualified and registered firms in the area, that our answer is to perform this calibration in house. Thanks for any help or advice in advance.