I read somewhere that you need to sharpen your Hollow Mortise Chisels when you first buy them. I read that after I used my first couple of bits (they didn't seem dull ) but I have just bought 2 more bits and thought I should handle them right this time. They are Delta Chisel and Bits sets - $50 each - they seem very sharp. My question - do I have to sharpen/hone these or are these ones OK right out of the box. If so, what is your preferred method of sharpening? Thanks in advance.