TLDR: Is machining the bare areas used to mount the rotors super important? or can a acceptable job be achieved by hand?



See shiny surfaces ^^

Long story long, had to get my rims chemically stripped due to thickness of original powder coat. Sandblasting place etched the rims afterwards, but also blasted the machined surfaces. The rims are set to be powder coated tomorrow. The shop mounting the rims knows about the blasted area, and we're thinking of doing the sanding by hand or small grinder. Is this completely inadequate?

Picture of rims in current state:



X marks previously machined area



X marks previously machined area