Or use a regular spring scale for weighing people, not a digital one. Use a piece of 2x4 on the scale, hook the string on the wood and push down into the scale.
You need to zero the scale with the bow and 2x4 on it for it to be accurate.
As far as your layout. Before you cut, widen your nocks about 1/4" and run new lines out to your fades. Cut on those lines. Your stave isn't dry enough yet. Leaving some extra will give you a bit of leway should the bow move a bit once it gets more dry.
While your cutting, remove most of the bulk belly wood too. It will help the stave dry better.