A lawnmower blade sharpener is a great tool to have if you own a lawnmower. Many people take their blades to a service center to have them sharpened, but why bother when you can do it at home? With a good bench grinder you can not only sharpen your blades, but you other outdoor tools as well. You can also get an accessory that fits onto your rotary tool, totally eliminating the need to get an additional machine.
If you are looking for blade sharpener there are several different types available on the market. The most popular type is simply an attachment that fits onto your rotary tool. What could be easier? Most tool attachments are made out of a durable nylon material.
These help to sharpen the blades to a perfect angle. You can also get an add-on that fits onto your power drill. Unless you plan on doing a lot of sharpening an attachment for your rotary tool or drill should suffice. Be sure that any attachments you purchase will fit onto your drill.
How to Sharpen Lawn Mower Blades
Approximately every 2 months of frequent use you should sharpen your lawn mower blades. If you do not want to continue to take it to a professional to get it done you should learn how to sharpen law mower blades yourself. 
It is not difficult, provided you have the right tools and take the proper safety precautions. If you continue to cut your lawn using dull blades the grass actually is ripped rather than cut. This is not clean and leaves your grass susceptible to disease.
Before you begin to sharpen the blades be sure to remove the spark plugs to avoid accidentally starting the mower. Remove the blade; do not attempt to sharpen the blades while still attached to the mower. Once removed, use your blade sharpener to sharpen at an angle. Be sure to follow any additional information that comes with your sharpening tool.