3D Printed Stuff

How I print:

Thermocouple Cooler

I've always wanted a Peltier element (I won't split hairs on the difference between a Thermo- and a Peltier couple here.), just because they are cool. When I saw one hanging in 梅澤無線 (see here) for around ¥1000, I just bought it on a whim and didn't know what to do with it for a while.

Back at home, I finally decided I wanted to see it running and freeze, like in those cool pictures on Wikipedia. That turned out to be tricky. Simply attaching a CPU fan with some thermal paste would either not cool below 0 (if the current was too low) or overheat the whole thing in a matter of seconds (if the current was too high — and by too high, I mean about ¼ of what the element should be able to handle). I needed a more powerful cooler. So why not water-cool the whole thing, directly on its surface? So I came up with this construction:

The whole thing was constructed in Blender.

It is indeed able to cool down the cold side to below 0 and create a nice little layer of ice. However, after a few minutes, the water would heat up too much for the thermocouple to be able to create a difference large enough. Not too surprising, given that it consumes about 60W. Overall, I'm still happy with what I saw. Actually cooling a can of coke with this is rather unlikely though.

Radio knob

The knob for setting the frequency on one of my father's old radios broke. So I thought I'd print one. Also, I was pretty fed up with how complicated it was to do something like this in blender and I had just recently learned about OpenSCAD. My father measured the old broken plastic part and I hacked the first version. The problem is that the plastic was much to soft and it would bend open with the original geometry. Thus, we experimented with different lengths for that opening incision. This is the current version:
This is the OpenSCAD source file for the knobs. While OpenSCAD doesn't give you pretty renderings, it's much easier to overview what's going on. It is now my preferred method to make 3D stuff.

Unfortunately, now the incisions were too short (or the insides too narrow). We helped ourselves by some post-processing with a fretsaw. Works nicely. Just the color is a bit…

Update: The Radio broke, and can't be tuned to a frequency perfectly anymore. Chances are that is because the pressure from the not quite perfectly fitting knob wrecked the frequency selection capacitor, a rather delicate open parallel-plate capacitor.
:(

Subway hands free

The Munich subway has one especially annoying feature: if it gets crowded, people always stand between the doors and nobody moves into the aisles. Given that the design of the train is 50 years old, it is not that surprising that this crowd dynamic wasn't prevented. Nevertheless, this opens a space where you can stand without being squished in a crowded subway. The only annoying part is that there is no good place to put your bag. The solution? This: CSG file

You can put it around one of the bars going down into the seats, and put your bag onto the hook. Unfortunately, I sold it to an elderly woman (for the manufacturing price) who approached me while I used it. I guess she now has the only existing copy that will be ever made (and I didn't even put a name or logo on it :/).

Office plant hook

My office needed more green. Hence
CSG file

To print the somewhat complicated geometry without any waste, the model was split in two as shown on top right. The first design, bottom right, was structurally flawed and caused me some clean-up effort… It also shows some layer adhesion and extrusion problems. Those were fixed by a higher extrusion motor voltage.

Outside Temperature/Humidity Sensor Stevenson Shield

My current dwelling place has a severe lack of places where I could mount some outside electronics, but I wanted an inside/outside pair of AM2320 (with a ESP32 wroom) to to decide whether opening the window can help reduce the awful inside air moisture. Hence:
CSG file

The sensor is simply glued in from below, with the two power and two signal cables dangling out from below (not pictured).

Fan in the CD drive slots

CD/DVD/whatnot drives are a dying breed, yet the case for my desktop (my wife's desktop?) came with three obviously unused slots for them. Time to improve the airflow.
CSG file

While the geometry is simple, it is surprisingly annoying to print. The small ramps in the four corners rest on a half-millimeter ledge. Print it too small, and it will fall right inside. Printing it too large and jamming it in did the trick, albeit it's slightly bent.

It also still lacks a net or filter to prevent at least the largest dust from falling in. I decided not to add a protective hexagon pattern on top of the fan because I like to live dangerously.