"Keeping a sharp cutting edge on big rotary mower blades saves fuel, time and wear and tear on equipment but it's a hassle to take off blades to sharpen them," says Clyde Williams, Leaksville, Miss., who came up with a quick-change blade for his rotary mower that he can change in seconds with just a hammer.

He notched the end of a mower blade with an angled cutout and a rectangular "key" for his removable blade to fit in to. The blade sets into the notches and wraps around the back side of the non-cutting side of the blade. Then a taper key is knocked under the back side of the removable blade to hold it in place.

"It's foolproof and safe because the taper key just gets tighter when the blade starts turning due to centrifugal force," says Williams, noting that the rectangular notch keeps the blade itself from slipping out of place as the blade turns.

"When the blade gets dull, I just reach in under the mower deck with a hammer, knock the key out, and slip off the blade. You can make up extra blades so that if you hit a rock or other obstacle in the field, you can make a quick change and maintain a sharp cutting edge," says Williams.