"Oren" wrote in message
news
On Mon, 05 May 2014 19:47:33 -0400, John wrote:

I take them off and sharpen on a bench grinder. With all the trees and
shrubs about my yard dropping twigs they get nicked and dull quickly.
Makes a noticible difference in performance and looks much neater, no
brown sheen on top from being ripped off rather than cleanly cut.

John

I'm glad a grinder works for you. Metal files work best for me and I
don't turn the blade edges blue.

I use a 4" angle grinder. Used carefully, no blue.