Ask Hackaday: How Do You Make A Hotplate?

Greetings fellow nerds. The Internet’s favorite artificial baritone chemist has a problem. His hotplates burn up too fast. He needs your help to fix this problem.

[NurdRage] is famous around these parts for his very in-depth explorations of chemistry including the best ways to etch a PCB, building a thermometer probe with no instructions, and chemical synthesis that shouldn’t be performed by anyone without years of experience in a lab. Over the past few years, he’s had a problem: hotplates suck. The heating element is usually poorly constructed, and right now he has two broken hotplates on his bench. These things aren’t cheap, either: a bare-bones hotplate with a magnetic stirrer runs about $600.

Now, [NurdRage] is asking for help. He’s contacted a few manufacturers in China to get a hundred or so of these hotplate heating elements made. Right now, the cost for a mica and metal foil hotplate is about $30 / piece, with a minimum order quantity of 100. That’s $3,000 that could be better spent on something a bit more interesting than a heating element, and this is where you come in: how do you build the heating element for a hotplate, and do it cheaply?

If you buy a hotplate from the usual lab equipment supplier, you’ll get a few pieces of mica and a thin trace of metal foil. Eventually, the metal foil will oxidize, and the entire hotplate will stop working. Repairs can be done with copper tape, but by the time that repair is needed, the heating element is already on its way out.

The requirements for this heating element include a maximum temperature of around 350 ºC. That’s a fair bit hotter than any PCB-based heat bed from a 3D printer gets, so consider that line of reasoning a dead end. This temperature is also above what most resins, thermoplastics, and composites can handle, which is why these hotplates use mica as an insulator.

Right now, [NurdRage] will probably end up spending $3,000 for a group buy of these heating elements. That’s really not that bad – for the price of five hotplates, he’ll have enough heating elements to last through the rest of his YouTube career. There must be a better way, though, so if you have an idea of how to make a high-temperature heating element the DIY way, leave a note in the comments.

Lego-Like Chemistry and Biology Erector Set

A team of researchers and students at the University of California, Riverside has created a Lego-like system of blocks that enables users to custom build chemical and biological research instruments. The system of 3D-printed blocks can create a variety of scientific tools.

The blocks, which are called Multifluidic Evolutionary Components (MECs) appeared in the journal PLOS ONE. Each block in the system performs a basic lab instrument task (pumping fluids, making measurements or interfacing with a user, for example). Since the blocks are designed to work together, users can build apparatus — like bioreactors for making alternative fuels or acid-base titration tools for high school chemistry classes — rapidly and efficiently. The blocks are especially well suited for resource-limited settings, where a library of blocks can create a variety of different research and diagnostic tools.

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You Can Learn a Lot from a Candle

Beginning in 1827, [Michael Faraday] began giving a series of public lectures at Christmas on various subjects. The “Christmas Lectures” continued for 19 years and became wildly popular with upper-class Londoners. [Bill Hammack], aka [The Engineer Guy], has taken on the task of presenting [Faraday]’s famous 1848 “The Chemical History of a Candle” lecture in a five-part video series that is a real treat.

We’ve only gotten through the first episode so far, but we really enjoyed it. The well-produced lectures are crisply delivered and filled with simple demonstrations that drive the main points home. [Bill] delivers more or less the original text of the lecture; some terminology gets an update, but by and large the Victorian flavor of the original material really comes through. Recognizing that this might not be everyone’s cup of tea, [Bill] and his colleagues provide alternate versions with a modern commentary audio track, as well as companion books with educational guides and student worksheets. This is a great resource for teachers, parents, and anyone looking to explore multiple scientific disciplines in a clear, approachable way.

If there were an award for the greatest scientist of all time, the short list would include [Faraday]. His discoveries and inventions in the fields of electricity, magnetism, chemistry, and physics spanned the first half of the 19th century and laid the foundation for the great advances that were to follow. That he could look into a simple candle flame and see so much is a testament to his genius, and that 150 years later we get to experience a little of what those lectures must have been like is a testament to [Bill Hammack]’s skill as an educator and a scientist.

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The (Copper) Crystal Method

One of the staples of kitchen chemistry for kids is making sugar crystals or rock candy. Why not? It is educational and it tastes good, too. [Science with Screens] has a different kind of crystal in mind: copper crystals. You can see the result in the video below.

To grow pure metal crystals, he used copper wire and copper sulfate. He also used a special regulated power supply to create a low voltage to control the current used to form the crystal. The current needed to be no more than 10mA, and an LM317 holds the voltage constant. However, that regulator only goes as low as 1.25V, so diodes cut a volt off the output.

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Reverse Engineering the McDonald’s French Fry

McDonald’s is serious about their fries. When they were forced by shifting public opinion (drunkenly swaggering around as it always does) to switch from their beef tallow and cottonseed oil mixture to a vegetable oil mixture; they spent millions to find a solution that retained the taste. How they make the fries is not the worlds most closely guarded secret, but they do have a unique flavor, texture, and appearance which is a product of lots of large scale industrial processes. [J. Kenji López-Alt] decided to reverse engineer the process.

His first problem was of procurement. He could easily buy cooked fries, but he needed the frozen fries from McDonald’s to begin his reverse engineering. McDonald’s refused to sell him uncooked fries, “They just don’t do that,” one employee informed him. He reached out to his audience, and one of them had access to a charlatan. The mountebank made quick work of the McDonald’s employees and soon [J. Kenji] had a few bags of the frozen potato slivers to work with.

What follows next was both entertaining and informative. At one point he actually brought out a Starrett dial caliper to measure the fries; they were 0.25in squares in cross section. Lots of research and experimentation was done to get that texture. For example, McDonald’s fries aren’t just frozen raw potatoes. They are, in fact; blanched, flash fried, frozen and then fried again. Getting this process right was a challenge, but he arrived at similar fries by employing his sous vide cooker.

He then wanted to see if he could come up with a french fry recipe that not only allowed the home chef to make their own McDonald’s fries, but improve on them as well. It gets into some food chemistry here. For example he found that the same effect as blanching could be produced by boiling the fries; if you added vinegar to keep the cell walls from disintegrating.

The article certainly shows how knowledge of the chemistry behind cooking can improve the results.

DNA Extraction With A 3D-Printed Centrifuge

[F.Lab] is really worried that we are going to prepare a DNA sample from saliva, dish soap, and rubbing alcohol in their 3D-printed centrifuge and then drink it like a shot. Perhaps they have learned from an horrific experience, perhaps biologists have different dietary requirements. Either way, their centrifuge is really cool. Just don’t drink the result. (Ed note: it’s the rubbing alcohol.)

The centrifuge was designed in Sketch-Up and then 3D printed. They note to take extra care to get high quality 3D prints so that the rotor isn’t out of balance. To get the high speeds needed for the extraction, they use a brushless motor from a quadcopter. This is combined with an Arduino and an ESC. There are full assembly instructions on Thingiverse.

[F.Lab] has some other DIY lab equipment designs, such as this magnetic stirrer. Which we assume you could use to make a shot if you wanted to. However, it’s probably not a good idea to mix lab supplies and food surfaces. Video after the break.

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“You Sank my Dysprosium!”: Periodic Table Battleship

Kids these days, they have it so easy. Back in the old days, we learned our elements the hard way, by listening to “The Elements” by Tom Lehrer over and over until the vinyl wore out on the LP. Now, thanks to [Karyn], kids can learn the elements by playing “Battleship” – no tongue-twisting lyrics required.

For anyone familiar with the classic “Battleship” game, you’ll wonder why no one thought of this before. [Karyn]’s version of the game is decidedly low-tech, but gets the job done. She printed out four copies of the periodic table, added letters to label the rows, and laminated them. A pair of tables goes into a manila file folder, the tops get clipped together, and dry-erase markers are used to mark out blocks of two to five elements to represent the ships of the Elemental Navy on the lower table. Guesses at the location of the enemy ships can be made by row and series labels for the elementally challenged, or better yet by element name. Hits and misses are marked with Xs and Os on the upper table, and play proceeds until that carrier hiding in the Actinide Archipelago is finally destroyed.

This is pure genius in its simplicity and practicality, but of course there’s room for improvement. The action-packed video after the break reveals some structural problems with the file folders, so that’s an obvious version 2.0 upgrade. And you can easily see how this could be used for other tabular material – Multiplication Table Battleship? Sounds good to us. And if your nippers catch the chemistry bug from this, be sure to take a deeper dive into the structure of the periodic table with them.

Now, if you’ll excuse me: “There’s antimony, arsenic, aluminum, selenium, and hydrogen and oxygen and nitrogen and rhenium….”

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