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WalterBright

Long ago, when I was in Cub Scouts, one of the projects was to build an electric motor. The parts list was:

1. a plank to form the base

2. several 6 inch nails

3. wire

4. a tin can (as a source of sheet metal)

5. tape

No magnets. But it worked perfectly fine when connected to a dry cell. Adventurous science lad that I was, I decided it would work better when connected to AC. So I attached a power cord and plugged it in.

A loud vibration ensued, and then it burst into flames. My mom wasn't happy.

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P.S. I still use tin cans as a source of sheet metal. There was a big storm a while ago, with tree branches whistling by at high speed. (Not a good time to be outside.)

Three holes were punched in the house by the branches, 1-2 inches in diameter. What to do, what to do. I took a coke can, slit it and unrolled it into sheet metal. Then cut a disk bigger than the hole, and epoxied it into place. Worked like a charm, and cost nothing.

I've used coke can metal for shingles and flashing, too. They don't rust.

there's also a plastic liner on them that I'm sure helps.

It also helps that they are made from aluminum which doesn’t rust like iron does.

And epoxy binds to aluminum just fine ? Epoxy is weird. What solid material does it NOT bond to ?

Teflon.

Yummy, my favorite!

Actually should be mostly fine since it’s pretty inert, unless you eat the stuff used to make it.

Like, actually making food atop a non-stick surface that flakes.

Polyethylene, like they use in food containers. Virtually nothing sticks to it unless specifically designed.

It does not bond to polypropylene and other low surface energy plastics

Terminology question - I understood those to be "high-energy" surfaces, because the chains are strongly bound. Is it a typo, or am I wrong?

It is really called low energy, it refers to the low attractive force of the surface, liquids bead up and do not wetten, in epoxy that results in small contact area and a weak bond, on a high surface energy material it flows into all the crannies and has enormous contact area and a strong bond.

It rusts just like iron, but the rust (AlOx, or alumina) stays bonded to the metal and actually protects it.

Rust being literal Fe2O3 makes a convincing argument that aluminium sure oxidises but doesn't rust pretty much by definition ;)

In other words: it rusts, but it doesn't rust like iron. It rusts in a much less destructive way because the aluminum oxide protects the rest of the aluminum from oxygen

it does not rust, it corrodes :)

I like that story. I fixed a microwave door latch with a beer-can shim and some decorative ribbon; we used it another 11 years.

One of my favorite sayings:

"Good judgement comes from experience; experience comes from bad judgement."

I commend your excellent use of bad judgement there, WalterBright (despite your mom's lack of enthusiasm)!

That 60Hz sound is a sure sign we did something very wrong. By the time you hear it it’s usually too late to say “Uh oh”

Username checks out.

Been there. Im gonna guess that 90% of HN folk have similar stories to tell.

The Cub Scouts in the 1960s were a lot of fun. Each den meeting involved a project. The other one I remember was we each built a kite from scratch.

Mine was a bit fragile, and the first gust of wind shredded the sticks and plastic film.

But it was still fun!

As a teen I built a flame thrower. No, I'm not going to explain how to build one. My dad told me that God looks out for little boys, because otherwise they'd never survive to adulthood.

When I was 9, I found a book of his "Rocket Manual for Amateurs". The opening sentence was something like "if you're fascinated by things that burn and explode, this book is not for you." Who could resist a teaser like that? I promptly read it cover to cover. He wouldn't let me buy any of the necessary materials.

"Rocket Manual for Amateurs" was my favorite book after I found it in 8th grade. In high school I had a chem teacher who would give me chemicals so I could experiment with what I'd read. A great book for budding Raketenkinder.

> if you're fascinated by things that burn and explode, this book is not for you.

Translation… ‘read me now!’

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