Hi guys. I’m trying to do the least amount of hand sanding and Makita palm sanding as possible. I use medium grit (70-140 mesh size) blast beads for smoothing semi-rough castings on aluminum valve covers. I still have to sand them with 220 then 400 before I start polishing with emery. Would it be worth investing in some extra coarse grit (50-70 mesh size) glass beads to use first then use medium in hopes of hand sanding a lot less? Please advise me in the right direction with any other ideas or comments. Thank you all for your time.