Alice Evans: Brucellosis, Or Why We Pasteurize Milk

It’s easy to forget how much illness and death was caused by our food and drink just one hundred years ago. Our modern food systems, backed by sound research and decent regulation, have elevated food safety to the point where outbreaks of illness are big news. If you get sick from a burger, or a nice tall glass of milk, it’s no longer a mystery what happened. Instead we ask why, and “who screwed up?”

In the early 20th century though, many food-borne illnesses were still a mystery, and microbiology was a scientific endeavor that was just getting started. Alice Catherine Evans was an unlikely figure to make a dent in this world at the time, but through her research at the United States Department of Agriculture’s (USDA), and later at the Hygienic Laboratory (now the National Institute of Health) she had a huge impact on the field of bacteriology, the dairy industry, and consumer safety. Continue reading “Alice Evans: Brucellosis, Or Why We Pasteurize Milk”

Spot Welding …Plastic?

Plastic milk bottles, when your project or prototype needs an urgent source of plastic, they are often the first thing to hand. Convenient and flexible, but strong at the same time and usually free, they’re the ultimate source of material in a pinch. However, when it comes to actually manipulating the HDPE plastic they’re made from, there’s often a challenge. It’s easy to cut, but not so easy to join. Conventional glues can have a hard time, making it difficult to bond.

Enter [zimitt], and a spot welding solution for joining HDPE with ease. Ok, so ‘spot welding’ might be a little optimistic given the speed of this process, but it’s useful nonetheless. To heat the plastic, a cheap soldering iron is recommended. A low wattage, straight-to-the-wall one does well, especially as they commonly have the washer-style end shown in the picture. To protect the plastic from burning, a BBQ mat is used – they’re temperature resistant and usually made with a PTFE surface.

First, place the two sheets of plastic face to face and sandwich top and bottom with the BBQ mat. Apply some heat to the mat with the soldering iron then, after a few seconds, remove the iron and provide pressure with a flat object to bond the plastic. [zimitt] used an espresso tamper for this which was ideal.

The results are impressive, and [zimitt] experiments with different plastics as well. Of course, you should exercise caution when attempting anything like this, given the health risks present when heating up different types of plastic.

HDPE is easy to recycle at home, and we’ve seen a lot of great uses: a plastic joiner’s mallet, plastic tiles, and even a filament extruder for 3D printing.

Carousel Of Cereals Mixes And Matches Custom Breakfast Blends

There are those who reckon the humble bowl of breakfast cereal to be the height of culinary achievement. Look askance if you must, but cereal junkies are a thing, and they have a point. The magic comes not from just filling a bowl and adding a splash of milk, but by knowing which cereals to mix together.

Who needs all that fussy mixing, though, when you can automate and customize your cereal dispensing chores? That’s the approach [Kevin Obermann] and [Adrian Bernhart] took with their Cereal Dispensing Machine, even if they went a little further than necessary. Laser-cut plywood forms a four-station carousel for off-the-shelf dry-good dispensers, each of which got a stepper motor to replace the wrist-twisting. The original motors were a bit too wimpy to handle the more rugged morning selections and were eventually upgraded to gear motors. The platform that supports the dispensers also holds all the electronics, including an ESP32 to run everything and host the web app needed to choose your poison. Plus RGB LEDs, because breakfast should look like a rave. Sadly, the team ran out of GPIO pins and were unable to run the peristaltic pump needed to add the milk. There will always be version 2.0, though.

If cereal isn’t your automated breakfast of choice, we understand. Perhaps a more [Wallace] and [Gromit] style breakfast machine would do, or a robotic peanut butter sandwich any time of day is a treat.

Continue reading “Carousel Of Cereals Mixes And Matches Custom Breakfast Blends”

Building A Better Baby Bottle Boiler

[Sebastian Foerster] hasn’t been at his blog in a while. He and his wife just had twins, so he’s been busy standing waiting for formula or milk to warm up. Being a technical kind of guy, he took a look at the tools currently on the market to do this, analyzed them, and decided instead to do it himself.

[Sebastian] looked to his Nespresso Aeroccino – a milk frother designed to give you hot or cold frothy milk for the top of whatever beverage you decide to put it on top of. It made the milk a bit too hot, 60°C, but once it got to the temperature, it would shut off, so if [Sebastian] could get it to shut off at a lower temperature, he had found the solution!

After taking the Aeroccino apart and going over the circuit, it seemed like a simple design relying on a resistor and NTC (negative temperature coefficient) thermistor connected to an ATTiny44 microcontroller. [Sebastian] didn’t want to have to reprogram the ATTiny, so he looked at the resistor and NTC. The resistor and thermistor create a voltage divider and that voltage is read in by the microcontroller through an analog pin. After looking up some info on the thermistor and replacing the resistor with a potentiometer, [Sebastian] could adjust the shut-off temperature while measuring with a thermometer. When he got the temperature he liked, he reads the value of the potentiometer and then replaces it with a couple of resistors in series.

Now [Sebastian] gets the babies’ bottles ready from fridge to temperature in about 25 seconds. He doesn’t have to worry about keeping an eye on the bottles as they heat up. We’re sure that getting two bottles ready in under a minute is much better on the nerves of new parents than waiting around for ten minutes. For more fun with thermistors, check out our article on resistors controlled by the environment or check out this bluetooth bbq thermometer!

Hacking Together A Temperature Sensor For Boiling Milk

Ever have trouble justifying your hacking to anyone from another generation? [Domen] presented his mother with a custom-made device that monitors the milk temperature as it boils on the stove, preventing boil-over. And he made the device robust, simple to use, and foolproof. To his mom, it must look like he’s a wizard — able to conjure up home electronics out of solder smoke and some plywood.

Of course, we know better. Inside his gadget is a simple temperature sensor, an ATtiny841, a very nice home-made PCB, a buzzer, an LCD, and some pushbuttons. [Domen] rubbed together a few pre-existing libraries, and had a working prototype inside a nice wooden box on the quick. It’s a simple hack, but imagine how this must look to a muggle. For the detailed incantations, check out [Domen]’s GitHub for the project.

Continue reading “Hacking Together A Temperature Sensor For Boiling Milk”

Milk-Based 3D Scanner

3D scanners don’t have to be expensive or high-tech because all of the magic goes on in software. The hardware setup just needs to gather a bunch of cross-sections. In perhaps the lowest-tech of scanners that we’ve seen, [yenfre]’s GotMesh scanner uses milk.

Specifically, the apparatus is a pair of boxes, one with a hole drilled in it. You put the object in the top box and fill it with milk to cover the object. A camera takes pictures of the outline of the object in the milk as it drains out the hole, these get stitched together, and voilà.

There are limitations to this method. The object gets soaked in milk, so it won’t work for scanning sand-castles. (It’s optimally suited for chocolate-chip cookies, in our opinion.) If the camera is located directly above, the objects have to get wider as the milk drains out. You can do multiple takes with the object rotated at different angles or use multiple cameras to solve this problem. The edge-detection software will have issues with white objects in milk, so maybe you’ll want to scan that porcelain figurine in coffee, but you get the idea. More seriously, the rate of milk drain will slow down a bit as the amount of milk in the upper box decreases. This could also be handled in software.

In all, we’re not surprised that we don’t see commercial versions of this device, but we love the idea. It’s based on this experiment where they dip a guy in a tank of ink! If you just drank all your milk, but still have a line-laser lying around, maybe this build is more your speed. What’s your cheapest 3D scanner solution?