4 BESS

[BobD]

I could be mistaken but ive had some readouts like this I believe to be from the same error. You can see the numbers going negative during the test, after the positive ones at the start but before the final result. This happens when the fixture is accidentally lifted, making it lighter than when the test started. The scale will show a negative symbol anytime there is a reading that's less than when the test began, the same as when you remove the test fixture to restring. However, when a positive pressure of equal or greater value is reapplied the symbol disappears. I think the blade made contact slightly on the side of the test media rather than directly from above, or the blade slided slightly, dragging the test media. The former can happen when the blade approaches on too steep of an angle like a guillotine, instead of the testing portion entering level. Either way, when the test media is cut askew, the horizontal pressure is not accounted for and the negative reading is not figured into the final number. Maybe it pinched the fixture sideways on the base relieving a few grams of it's original weight or part the blade was positioned low enough to very slightly raise it on its own.