for all their defects i only use CF or plastic props, i guess cos of the fear of mucking the beryllium bronze or ss ones (and laziness ultimately). There's a 3 part video on youtube on how to go about it and it's quite good actually, but i keep procrastinating and my unsharpened metal props are still lying there - unloved and forgotten ;-) I have sharpened props before, but not balanced, so i got mediocre results - one day perhaps.....