Ensure Accurate Weights

When you drop off your scrap metal, ask to jump on the scale. If you know how much you weigh, you'll know how accurate the scale is. If they don't allow it, I wouldn't trust them.

I hop on the small scale once in a while..... Large scales here in canada are regulated by the Govt and are inspected and calibrated at least once a year by the federal govt... I've seen them at my scrap yard before.

Sounds like a good idea.