The easiest way to keep your planer knives in good condition without removing them from the machine.
The hones consists of two slips (one Aluminium Oxide and the other Diamond), held at an angle in a wooden handle for topping and backing the blade. Applying the hone to the edge of the blade and moving it along the length with a uniform pressure should restore the blades to their former glory.
Please note these are for honing the blades, they will not restore chipped or very dull blades.
The Aluminium Oxide Hone is suitable for HSS edged blades only and the stones will wear with use over time, while the diamond hone will suit both HSS and TCT edged blades and considering the amount of use they will receive, will likely last a lifetime.