I have never owned a stand up mower. I got a loaner from deere while my machine is in the shop. Every loaner I get has extremely dull blades. I decided to take blades of to sharpen them. I took impact wrench to them. I did not know they had a top nut on top of spindle. I got it off and bolt is about 1 ft long. It had a ton of washers on it. Is this normal?