Cool. But with an old lawnmower blade not sure you'd need to harden and temper them. I think my router wrench is softer than one from a lawnmower blade. Be interesting to compare tho.I do allot of metal work as well as wood work. I made a few thin offset wrenches for my router table. I cut them out of an old lawn mower blade with an acetylene torch and a hand grinder. I then hardened and tempered them by quench cooling in oil and heat treating. I would think harbor Freight customer service could help you out but if they can't you can always make one. If you measure the size of the nut find a wrench that is the right size. If the wrench is too thick just grind it to make it thin enough to fit take a little at a time and keep the wrench cool by quenching make sure it it doesn't start changing colors like to blue or brown that means the temper is coming out. Hope that helps and welcome to the forum.
Not so much as you might think. My bench drill press is something over 15 years old. Switch went within a week, Lowes had one for $5, and it has been working great ever since. HF angle grinder, still going strong after I don't know how many years. Had one or two more of those, but they seem to have walked off with my younger son. HF bench saw, at least as old as the drill press, still working. A LOT of my HF stuff disappeared with my son, long before I could break any of it.Most everything at HF that has a motor or needs accurate measurements is a "don't touch".
Stoopid computer. Just ate everything I had typed.Theo After I cut the wrench out with the torch bending and grinding to the right shape it takes the temper out of the tool steel. I had to bring it back so it would not bend or be too hard to crack. My father worked at Xcelite tools making tools for many years.He taught me so many things about heat treating and working with metals. I wish I remembered half the things he tried to teach me.