I followed the directions in placing my caliper in the clamps on the AMP. Then I wanted to check accuracy with some machinist's angle standards I have. Measuring several of them and converting the caliper reading to degrees using the iPhone app, I was disturbed to find the measured angles large by a couple tenths of a degree. Alternatively, setting the angle using the data engraved on the AMP, I found the standard angle didn't fit well - about 5 thousandths gap at one end of its approx 2" length. What's going on? (I'd double-checked the angle standards with a Brown & Sharp machinist's protractor and another protractor I have and they looked right on.)
Looking carefully at my AMP, I noticed in following the directions, I had worked to make the caliper's position in the clamps balanced, with the beam tight against the AMP leg, held by the clamp "F", but the clamps themselves were slightly uneven. That is one was slightly higher on the caliper than the other. So, I repeated the setup, but this time used a small straight-edge along the lower edges of the clamps as an added alignment constraint. After re-clamping, the angle standards and AMP readings correspond very well.
Statistics: Posted by firstname.lastname@example.org — Thu Mar 29, 2012 7:46 am