Don't go cheap on the scales , I bought a scale at a farm store used to weigh feed , they looked decent and cost about $30 and went to 70# , more than I needed weight wise at the time .
I was working on a bow that I needed to get the weight to 55# , the second time I used the scales on the tillering tree the scale have it up at 52# , my heart sank when the bow flew off the tree , a good inspection and a few nervous pulls on the string made me feel better no damage to the bow but the scales were scattered everywhere .
No more cheap scales for me and they will go to 100# minimum to be sure they hold together .