Originally Posted by Team Duratrax
Use either a comm stick or a pencil eraser. 1500 grit sandpaper works to.
Those things work to clean the comm surface, but they do not TRUE the comm, which is what a lathe is for. As brushes wear, they also put wear on the comm surface, & as that happens, the surface becomes uneven. And as that happens, the brushes will begin to bounce on it as the motor runs, which only makes the motor lose performance & also accelerates the brush & comm wear. And only a lathe can get the comm surface perfectly round(true) again, so the shot answer is no, there's no cheap alternative to cutting the comm(because comm sticks & sandpaper do not do the same thing, they only clean it)....