More Cooling Hardware

I wrote about EZCoolDown cool packs; now for more cooling technology!

Fighting Thermodynamics

Cool packs don’t like to be stacked in a fridge when they’re warm; it means they only cool down slowly. Some kind of mechanical separation apparatus—more commonly known as a shelf—is wanted.

I keep my cool packs in a mini fridge along with some fizzy water of the plain and flavoured, caffeinated varieties. The fridge came with shelves, but I had to take them out to make the drinks bottles fit. Disaster!

Fortunately, I have a means for solving such a problem: I can 3D print shelves!

Another Useful 3D Print

The first thing I tried was simply grabbing a design for a free standing stackable shelf from the Thingiverse and resizing it.

This, of course, could never work: you can’t resize a 3D design and have the material thicknesses and tolerances still make sense. But printing something of the right size, even if I knew it would not work, was a good way to get a handle on the problem. Here it is:

First Attempt

The resulting print was ridiculously weak. The reason the surface looks white is that you can partly see through it to the table underneath.

But, I learned a lot: I learned that the problem of making the right standalone shelf was going to be really hard. The cool packs only just fit in the fridge door, where I was intending to stack them; and they only fit folded. The shelves were going to have to organically meld with the cool packs in some beautifully perfect design to work.

After considerable head scratching I found a way out: instead of self-standing shelves I could use the slots already built into the shelf for the shelves it came with. Those shelves weren’t useful because they were too deep—but I could simply print narrower ones.

I had reduced the design problem to merely correctly sized rectangular plates.

Merely Plates

There was still some challenge remaining, however: to span the requisite gap, the shelves would have to be wider than my 3D printer can print. So, it would have to be a print in two pieces.

And, of course, it would have to be strong enough. There followed a series of iterations in which I attempted to find the right shape:

Second Attempt

Third Attempt

Fourth Attempt

I initially tried fixing the two pieces together with superglue, but quickly gave up on that idea; sticking tape wrapped around the join is much stronger, and this is purely functional—it doesn’t have to look nice.

I made single “sticks” of the right strength and length, and printed two for each shelf.

This worked!

Fourth Attempt In Action

But, it was annoying: the shelves were unstable and would fall out of their slots at the slightest provocation.

The next—and hopefully final—iteration was to add cross bars into the design, rather than letting two disconnected “sticks” try to work as a shelf:

Fifth Attempt

This seems to work well.

Fifth Attempt In Action

In this last image the cool packs are in the sleeves that make them wearable as cooling collars.

Outdoor Cooling

I felt the need for some cooling outdoors recently, so I’m trying another product from EZCoolDown: a baseball cap that you fill with a small amount of water for evaporative cooling.

So far I’ve used it for a few hikes. I wouldn’t say it’s life changing, but it definitely feels good to have a cool barrier between myself and the glaring sun.

Evaporative cooling is even more efficient than wearable cool packs, so I’m happy to have added this to my cooling toolkit.

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