So my mother told me that her lawnmower is broken, and I look at it, and these are the holes that the bolts go through to mount the motor.

It seems that at some point she hit something and bent the blade, which put it out of balance and so it vibrated itself to death.

A few weeks ago when I was thinking about wheels, I thought about how people who build cool shit on the internet have a welder. So I looked up how much it would cost to get one, and it would only be about $300, safety gear and all. However, I didn't get one, because I couldn't come up with any idea how it would actually solve any problem I had, nor could I think of more than a couple of times in my life when it would have been useful to have one.

However, I was now looking at a broken lawnmower which could either be replaced for $300 or repaired for $300. Well, assuming I can figure out how to weld anyway.

Figuring that I shouldn't melt the mower right away, I decided to practice on scrap metal.

The first scrap metal was the bent mower blade. I cut it in half with an angle grinder, then tried some practice welds to the side of the cut just to see what happened, then tried welding where the cut was. It turned out like this:

I then flipped it over and tried with full power. That turned out a little better.

Of course in both cases I couldn't really see what I was doing because the welding mask wasn't quite working correctly. Even on its least-darkening setting, it was so dark I couldn't see anything but the spark.

Wanting to see how good this weld was, I did my best to break it. I bent so hard with pliers that the blade was flexed, but the weld held. I then swung it at some bricks a couple of times before it slipped from my hand, bounced off the brick, and then into my leg. At that point I decided to stop before I hurt myself and just consider it to be well enough welded together.

I then tried some thinner pieces of metal and, I wouldn't have expected it, but thinner metal is harder to weld. Even on the machine's lowest setting it's kind of prone to just melt right through it.

This turned out like shit with all the holes, but it kind of worked in that when I bent it, the unwelded metal turned out to be the weakest part.

However, some other attempts at it turned out worse, and about 5 mm of one attempt actually looks like it came out perfect. This is some thin metal though, like I think it might be thinner than what the welder even claims to be able to weld.

I also tried welding this washer to this other piece of metal:

This broke right off with almost no effort at all. I thought about it and realized it might have something to do with the fact that I didn't really clean either piece of metal since they both looked clean. So I cleaned them and tried again:

This time when I broke it, it broke through the weld on one side after bending it back and forth a few times, but also just broke through the unwelded part of the washer on the other side. So I'd say that's plenty strong enough.

...and that's about the thickness of the metal in the mower too. I'm going to practice some more another day before I attempt repairing the mower, but it seems like it'll work out, and even if it fails, it would fail by me melting a hole in it, so I guess I could just throw more metal on top.