An interesting post from Hackaday:
So you’ve got a broken gear for you model helicopter, and don’t have a 3d printer handy. If you need your little helo flying right away, [James] wrote in to tell us about his solution. As you may have guessed from the title, he made a tiny mould and produced a copy of the gear he needed with it. Given the complications of printing or some tiny subtractive method, this little gear turned out really nicely!
The video after the break shows all the steps for doing this procedure. If you’d rather just skip to the results, check out around 10:00 to see the finished gear, and eventually the little guy in flight. As noted, he did have to drill a hole in the middle of the gear after the mould process, but this was the only machining operation.
The helicopter gears worked out nicely, but be sure to check out some of the other really interesting projects on the [xrobots], some of which we’ve featured here!
Comments
I've made a few molds, nothing that small. He could have included the shaft in the original mold and then when it's time to make a gear drop a shaft in and no drilling needed.
Epoxy molds are also one way to go. Can easily modify them and if broken well repairing is as easy as modifying. We should have one opensource molding machine. Let's see when this scene will get facelift as so many others have it already.
with mold making you can always "repair" the damaged part... that is what I do.
For example, that bad gear... what if you did not have a good one around?
well you can "fix" these 3 bad teeth with clay or glue in bits of plastic and shape them with a knife.
They will not be strong enough to make the gear work but they will make the good imprint in the mold so you can cast it. It's really not a perfect part but for most application this is good enough.
I want a CNC machine that would cut this in alu instead of plastic! :)
That can be a problem at times:(
The problem is when you don't have a prototype to make a mold off of.
I want a 3D printer SO bad!
This is my preferred method for making plastic parts. While 3D printers offer a lot of potential they just aren't as efficient and cost effective as mold compounds and plastic casting resins are. I do see this changing in the near future, but in the meantime I will stick to the good ole fashion way of making plastic parts.