Quote:
Originally posted by Koci
We weighed our robot prior to inspection to make sure we would pass, and weighed 129.7. At inspection, on the exact same scale, the first time we got 130.2. We picked it up and set it down again, and got 130.0. We took it to another scale, and again got 130.0, so they let us pass.
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Based on your numbers I would say your "practice" weigh-in was on the far right scale, the first "official" weigh-in was on the middle scale and the last one was on the far left scale. The numbers would then match my observations on the relative sensitivities of the different scales used.
The inspectors all knew that we were getting different weights on different scales, but that the scales were consistent to themselves. So each one would give the same weight (within 0.1 lbs) for the same object, but what one weighed at 130.5, another would would show at 130.0 and the third about 130.3.
Since we didn't have a calibrated weight there way no way for the inspectors to tell which of the three scales was correct. I suspect it was the "lightest" one, because nobody commented on a weight difference from a previous regional on that one. Or maybe they were just too smart to say "Hey we lost some weight!" in front of an inspector.
Since we had no idea which was right, we passed anybody who could show 130.0 or less on any scale. If a machine was close, we used the light scale.
The scales used were accurate enough for the job, but the calibration was probably off due to stuff that happened in transit. It happens. Maybe somebody would like to find a set of certified weights we can use for the Championship next year? I don't think FIRST wants to have to haul them around everywhere.
Remember, your target weight should be something less than 130 anyway. Leave yourself at least a pound of margin to take the differences in scales into account. You can always add a little weight if the scale will let you get away with it, it's a lot harder to take it off.