Sharpening Ride-on lawn mower blades

[Aughavas]

Hi, what is the correct method for sharpening a Ride-on lawnmower blade. I bought the lawnmower second hand and have no manual. Should I sharpen the blade to a sharp edge, like a knife or have a flat edge?
A link to a cross-section of the blade would be fantastic.
Thanks

[pawwaw17]

its sed that they should be sharpend every year or so, depending on use, an angle of 45 deg. how ever much you take off one blade should be taken off the others to keep the blades ballanced when they spin. but the blade should be sharpend from one side resembeling a chisle aposed to a knife, never felt the need to be to fussy myself, the amount of abuse the blades get mean they would damage very easy if you had a razor edge.

[Aughavas]

Thanks pawwaw17, everything in your answer makes sense. Thanks again.

[Thunderbird+]

On some makes of mower you can just turn the blade over, if it has a cutting edge on each side, this will prolong the sharpening interavals.
As Pawwaw says, you dont need a razor sharp edge, It's mainly the high speed that does the cutting and a quick touch with an angle grinder is usually enough to restore a badly rounded edge.
PS, I'm sure if you had a manual, it would say- Disconect the spark plug before doing any work on the blade. You can get a compression kick even if the switch is off!