I have a crappy 12Kg spring scale, it works wonders, paid for itself first time I used it!

Its needs adjusting all of the time but thats easy, little button knob on its top, fits in my pocket or toolbag.
I have a few 'setting weights' I use to compare its accuracy but find it to within 100gms in a pinch, so I keep the 'above the Kg' surplus to about 200gm to 300gm.

To weigh more than 12Kg?
Put the metal in a sack, hook the scales on one side of the top of the sack, grab the other sidecorner in my fingers & lift it up level, check the display & double it!



I'm impressed with the new digital hanging scales, cheap & accurate, no arguments there.