Instructables
Picture of Cast Aluminium Gears
This instructable will show you a technique of casting known as lost foam casting, to create aluminum gears. The gears in this instructable do not have any real purpose other than decoration, but with more time and patience, you could create gears for actual use on something. Please vote and favorite!
 
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Step 1: Watch the Video

I made a full tutorial on creating these gears. I recommend watching it, as it goes a little faster than reading this instructable, and goes into further detail.

Link: https://www.youtube.com/watch?v=ALU6_bUq9qo

Step 2: Templates

Picture of Templates
14, 7:01 PM.jpg
14, 7:01 PM.jpg
For this project, I use Matthias Wandel's gear generator to make templates for my gears. The generator is made for creating wood gears but it worked just fine for my purposes. The site is very simple to use and is totally free. After I made a set of gears, I printed them out on normal printer paper and glued them with glue stick onto some flat pieces of polystyrene foam.

Step 3: Cutting Foam

Picture of Cutting Foam
14, 7:01 PM.jpg
14, 7:01 PM.jpg
After the glue is dried, I went and cut out the gears with my homemade hot-wire foam cutter (Instructable coming soon!). Make sure to follow the lines as close as you can, so the gears fit together.
laffinm (author) 3 months ago
Well, when the molten aluminum, which is very hot, first touches the foam, the foam rapidly disintegrates and the aluminium fills the mold. You might think that the sand would cave in directly after the foam is gone but actually the fumes of the burned foam slightly harden the inside walls of the cast, and they stay firm enough for the metal to full it completely. I hope this helps a little bit, as it can be very confusing.
mkovtchega3 months ago

I don't know pretty much anything about casting, but I want to try it. So I don't really understand how the molten aluminum takes the gears form?

gasperi4 months ago

How many cans do you need to make something that size?

pfred2 gasperi4 months ago

I've cast cans into ingots and it takes quite a few cans. The main trouble with melting down cans is how thin they are. Being so thin they tend to oxidize more than they melt. Oxidized metal is not the nice shiny stuff that you're looking for. I find that submerging the cans to melt them helps out a lot, but that has its own hazards doing it too.

The other thing to note is that cans are pure aluminum. Pure aluminum is not the best casting alloy of aluminum, it isn't an alloy at all. You can alloy your pure aluminum with some zinc and have a better material.

jarikcbol pfred24 months ago

If you want to add zinc to your alloy, remember that pennies are made from zinc, with a copper coating, which can be removed any number of ways. And no, its not illegal to melt pennies down for the zinc, the law about messing with money is very specific, and indicates that defacing them to change their value is illegal (making a silver dollar out of a quarter) but turning them into something that is not money is perfectly fine.

pfred2 jarikcbol4 months ago

You would have to add quite a bit of zinc to reach the ratio that Zamak is. Diecast metal is mostly zinc. I think that would be more economical material to use than pennies.

Jobar007 pfred24 months ago

This is exactly what I was going to post: cans are pretty cruddy to cast with. A better solution would be to go to craigslist and find an aluminum block lawnmower in the free section and haul it off. Yes, it does require a lot of work to disassemble and clean (clean material = less crap to skim), but it is a casting alloy and will be night and day in difference in your results.

laffinm (author) 4 months ago
About 20-30 was enough for this project. You want to have a little more than you need just in case. Also, if you crush the cans into a small ball, they will produce more liquid.
baecker034 months ago
collect hard drives, good aluminum for use.
laffinm (author) 4 months ago
I actually did poke a few vent holes but didnt bother to write about them. Sorry about that :)
neo716654 months ago
On larger items it helps to put vents to allow gas and air escape. You still sometimes end up with voids but they often help eliminate them.
babaguru4 months ago
I wonder how heavy it would be they look pretty chunky
Tom Hargrave4 months ago

My uncle used to cast replacement Studebaker parts like door handles from melted down pennies, but pennies were 100% copper back then. He used the lost wax process then would clean & polish them up and send them out to a plating company to have the parts nickel then chrome plated.