Sharpening wood planer blades can be accomplished in five easy steps.
Step 1 - Assemble Blade
Set the guide on a pure and flat surface. Then put your blade into the honing guide making certain the guide holds the blade in the bevel-side down position. Adjust it so that the full bevel connects to the surface.
Step 2 - Add Oil
Using tapping oil, you should now oil your whetstone. Tapping oil is designed to clean off metal.
Step 3 - Remove Blade Nicks
If there are blade nicks in need of removal, only apply the whetstone’s coarse side. Work it with a pushing action, instead of pulling because pulling may cause a blade edge burr.
Step 4 - Move Blade
After you’ve removed any nicks, move the blade across the whetstone by applying pressure where the blade doesn’t move. If the blade rocks at all, this may result in a curved edge on the planer blade. This might require you to reshape again.
Step 5 - Do Blade Maintenance
You’ll also want to periodically check your blade, assuring that its bevel remains in good shape. Tilt it and turn it toward the light noticing how light reflects upon the bevel. If it’s in good shape, it should look absolutely flat.