Seems to me basic calibration should be pretty simple for the DIY guy. One inch pound is literally a one pound weight on a moment arm of one inch. Say you have a combo end wrench 10 inches long.... put the open end on the torque wrench square drive & hang a 1 pound weight from the combo end.... it should read 10 inch pounds. The wrench should be 90 degrees to the torque wrench handle. Yes?