grind away
(at someone) Fig. to needle, criticize, and nag someone continually. Why are you always grinding away at me? Leave me alone. Stop grinding away!
grind away (at something)
to crush something into particles continually. The machine ground away at the rocks, making tons of gravel. It ground away, making a terrible noise in the process.
grind something away
to remove something by grinding. Grind the bumps away and make the wall smooth. Please grind away the bumps.