I use a split shaft with various sandpaper grades, but I agree that 320 or 400 are best for most situations. Aggressive enough to grind down the support nubs but not so much that it won’t easily mar the surface of the model. 
I use a split shaft with various sandpaper grades, but I agree that 320 or 400 are best for most situations. Aggressive enough to grind down the support nubs but not so much that it won’t easily mar the surface of the model.