Fix the back head of the hatchet in the middle of your knees and use a file to sharpen the edges. The bigger the file you use, the more razor-sharp your blade becomes. Another way is to place the camping axe on a flat and stable surface, then use a whetstone to angularly match the height and brush its edges. If you want to use a grinder, make sure to keep a bucket of water to cool the blade after every round.