This YayLabs Play and Freeze Ice Cream Ball Ice Cream Maker has two identical screw lids on opposite sides of a sphere. In one you put heavy cream and whatever else you want in your ice-cream. In the other you put lots of ice and rock salt. The salt lowers the melting point of the ice, dragging the cream colder than where water would otherwise freeze. You roll the ball around and after 10 minutes or so, have ice-cream.
The problem is that due to various thermal effects the lids get very stuck. Like, hitting-them-with-a-hammer-doesn’t-work stuck. My first theory was to make a cylinder with a notch in it and hope that provided enough grip top open the thing. So I designed and then 3D printed this in 30 minutes:
Which goes on like this:
And of course, that didn’t work. So I added a handle for a lever using OpenSCAD:
Then put it through the printing process using Simplify3D:
Ending up with a basic lever tool:
Which works great!
This isn’t solid plastic. Simplify3D prints a three-dimensional crosshatch mesh inside the solid and it apparently has more than enough strength to open the ice-cream maker. It took about 5.5 hours to print and a few dollars of plastic. I was hoping that some similar tool already existed, with a variable width on the notch piece, to open things like this (or CameklBak’s for example!) But, I couldn’t find anything with my various searches.
I can’t help but think back to The Whole Earth Catalog – Access to Tools:
Making your own tools is a powerful experience, physical tools like my lever thing or ephemeral like software. Try it.
It also made me wonder if this is approximately how things will work out when we get to Mars – shipping lots of 3D printers instead of parts since the cost of delivery will be pretty high and we don’t really have a clue what they’ll need on the ground.
The total design time was about 10 minutes, and the code is all static numbers which reflect the rough measurements of the lids. It helps if you already know some geometry and have the OpenSCAD cheat sheet open.
Someone could take it and make it a more generic tool for various lids by putting different cylinder-notch combinations down the length of the tool, instead of just one at one end. It could also use both sides. Or, various cylinders with a notch on top to take a lever. The lever could be printed or use some common size, like a screwdriver that you could slot in to use as a lever.
The obvious thing to do would be to print a nut in to the top of the cylinder so you can use a wrench. I don’t think it’s very likely the 3D printed plastic would handle the stress of that however. Presumably things like this exist in metal already somewhere, and we can print in various metals today too.
The length of the lever is about the limit of what my printer can print – about 20cm or so, which is less than a foot.
The files are all here on Thingiverse.