I
InspectorRalek
I have always used the three screw method of flatness measurement. I encountered a rectangular part which using the three jack method displayed a flatness .105.
Upon attempting to reject this as it was grossly OOT, I received instruction to try a different method which seemed like a problem to me as I believe the three jack method to be tried, true, and definitive. The suggestion was to place the part on four jacks. One on each corner. Adjust until two opposing corners are at the same height. Then make the other set of corners the same height. So top left and bottom right are now the same height and I have zeroed my height gauge on them and the other two opposing corners are both .038 higher than the two 0 corners. Upon scanning with the height gauge I measured a flatness of .055. The parts are still OOT, but they are profoundly better as the surface now fits in a smaller zone. I don't know if I should accept this method. Is there a fundamental flaw that I am just not seeing? Any feed back would be appreciated.
Upon attempting to reject this as it was grossly OOT, I received instruction to try a different method which seemed like a problem to me as I believe the three jack method to be tried, true, and definitive. The suggestion was to place the part on four jacks. One on each corner. Adjust until two opposing corners are at the same height. Then make the other set of corners the same height. So top left and bottom right are now the same height and I have zeroed my height gauge on them and the other two opposing corners are both .038 higher than the two 0 corners. Upon scanning with the height gauge I measured a flatness of .055. The parts are still OOT, but they are profoundly better as the surface now fits in a smaller zone. I don't know if I should accept this method. Is there a fundamental flaw that I am just not seeing? Any feed back would be appreciated.