I bought a $35 digital bathroom scale...

Those scales are SO innacurate! They are for fat women who want to think they lost weight. [Linked Image]

I also don't think this is a very accurate way to determine length used. Each time you start a new spool you need to weigh it and subtract the weight of the spool, especialy if you have multiple manufacturers. If you think they all weigh the same it's because your scale is crap. A decent (and accurate)digital shipping scale will run you about $200.

-Hal