My scale is probably off a tiny bit too.
Bart get a true weight-folded bill/new coin (in the day of testing the drug scales=gram was a $20 dollar bill-so I was told) :0
For electronic scales there is 4 load cells typically in most scales. Platform scales provide a accurate weigh regardless of position of weigh.
(If a yard was paying a nickel more for something it only took a inaccurate scale to make up that nickel that was given.
So I just stated for the customer to stand on every corner of the scale-then in the middle-every weight should be the same on the read out-and that readout should be visible to the customer.)
Until there is a lazy cell or a dead cell.
Put the bill/coin on each corner of the scale and in the middle. All 5 weights will be the same if the scale is correct.
I certified my weigh scales quarterly in the scrap business 2 platform, one counter, one for testing/PM scale that weighed 0.0000 (scientific standard almost).
I was the only dealer that had an independent scale company do this testing without any appointment.
They showed up and if somebody was being weighed up-they had to wait till the testing was done. The paper of results was posted by the scale.
What this proved there was no funny business going on with the scales or product. Just to put it into perspective in 13 yrs I started will a visa card and at the signing of the sale my sales were $5.5 mil. all done on honesty of that scale.
Oh I was loathed by the pirates that wanted to play the game of I screw you/you screw me game in the recycling industry.
I truly believed in the honesty of the weighing system-I prided myself in giving every customer the same shake-from the street person-to the owners of corporations.