I damaged this blade by slicing along a dead fruit tree stump that was hidden in grass. Around 15cm of the edge was burred over, with a significant chunk out of the blade at one spot.
I repaired this at the Small Farms Expo in the Huon Valley after setting up our stall... it was a case of "have to" as it was the only blade I'd taken with me to demonstrate mowing! It must've been a pretty convincing repair since I made a few converts that day.
Basic steps:
1. Clean the edge, on both sides of the blade
2. File off the burr and use the round section of a half-round bastard file to cut into the notch, and a little deeper.
3. File off the 'shoulder' of the 'dent' just made in the blade, to make the descent into the blade's edge more gradual.
4. Draw out the edge around the deep repair - starting a few millimetres into the blade - very slightly so as to make the edge a little more uniform. Not too much or the blade becomes too thin there and will just get damaged again.
5. Peen the very edge to give an edge that can be honed to sharp.
