Tips for getting finer flour and also how to use coarse flour I've ground at home

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Hey guys, I just bought my first home mill and a big bag of berries to grind. With the flour I've been able get a sourdough going and have baked a couple loaves of bread and several batches of cookies. The flavor has been great but I the finest I've been able to grind is only slightly finer than sand. I run it through the mill a couple times but anymore than that doesn't seem to make much of a difference. Any tips on how to get a finer flour? Or some inspiration for what to use this coarser stuff for?