The build is based on the designs described in the book “Build an EDM” by Robert Langolois. An EDM works by creating lots of little electrical discharges between an electrode in the desired shape and a material underneath a dielectric solvent bath. This dissolves the material exactly where the operator would like it dissolved. It is one of the most precise and gentle machining operations possible.
His EDM is built mostly out of found parts. The power supply is a microwave oven transformer rewired with 18 gauge wire to drop the voltage to sixty volts instead of the oven’s original boost to 1.5kV. The power resistor comes from a dryer element robbed from a unit sitting beside the road. The control board was etched using a hand traced schematic on the copper with a Sharpie.
The linear motion element are two square brass tubes, one sliding inside the other. A stepper motor slowly drives the electrode into the part. Coolant is pumped through the electrode which is held by a little 3D printed part.
The EDM works well, and he has a few example parts showing its ability to perform difficult cuts. Things such as a hole through a razor blade., a small hole through a very small piece of thick steel, and even a hole through a magnet.
Copenhagen Suborbitals just launched their latest amateur liquid fuel rocket. Why? Because they want to strap someone to a bigger amateur liquid fuel rocket and launch them into space.
We’ve covered them before, but it’s been a while. While they make a big deal of being amateurs, they are the least amateurish amateurs we’ve come across. We’ll forgive a lot as long as they keep making great videos about their projects. Or posting great pictures of the internals of their rockets.
The Nexø I rocket they recently launched claims to be the first guided, amateur, liquid-fueled rocket. There is a nice post on the guidance system. It was launched from a custom built barge off the shore of Denmark, which allows them to escape quite a few legal hurdles around the launch. The rocket flew beautifully. That is, it went only away from the ground; no other directions. Also, it didn’t explode, which is a lot to expect from even the biggest players in the field.
Copenhagen Suborbitals continues to do amazing work. Hopefully their next rocket will be even more impressive… for amateurs, that is.
Want to bring your fine antique furniture into the 21st century? Make it clear with transparent wood. That’s what [blorggg] is doing over on Hackaday.io, and it looks cool enough to have a some interesting and novel applications besides small, clear test pieces.
The recipe for transparent wood is surprisingly simple, and all the ingredients are readily available from a drug store or home supply store. First, the wood is soaked in a bath containing lye and sodium sulfite for several hours. The wood is then bleached in a bath of hydrogen peroxide. After this, the wood is transparent, but very weak. Infusing the wood with epoxy resin strengthens the wood.
We first heard about this process back in May when the the paper [blorggg] based his recipe on came to light. the lye and sodium sulfite are frequently used in the paper industry to dissolve the lignin in wood. By removing the lignin, the microscopic structure of a piece of wood becomes just a series of tubes and thin cell walls. After bleaching, adding the epoxy shores up the now exceptionally weak structure of a block of wood.
While the original researchers only made two pieces of transparent wood – end grain and cross grain basswood, inexplicably referred to as R-wood and L-wood – [blorggg] is taking this much further. He’s using plywood to great effect, and the process is simple enough to expand to woods a bit weirder than basswood. If you have some scrap walnut, burl, or some exotic wood, this might be something to try out.
If you’ve been reading the news lately, you doubtless read about the find of a really big new helium gas field in Tanzania. It’s being touted as “life-saving” and “game-changing” in the popular media, but this is all spin. Helium is important for balloon animals, scientists, and MRI machines alike, but while it’s certainly true that helium prices have been rising steadily since 2000, this new field is unlikely to matter all that much in the grand scheme of things.
The foundation of every news story on helium is that we’re running out of the stuff. As with most doomsday scenarios, the end of the world’s supply of helium is overstated, and we don’t just mean in light of the new Tanzanian field. Helium is the second-most abundant element, making up 24% of the total mass of the universe. And while the earth has a disproportionate amount of heavier elements, helium is in rocks everywhere. It’s just a question of getting it out, and at what price that’s viable.
So while we’re stoked that the era of (relatively) cheap helium can continue onwards for a few more years, we’re still pretty certain that the price is going to continue to rise, and our children’s children won’t be using the stuff for something so frivolous as blowing up party balloons — it’ll be used primarily, as it is now, where it’s more valuable: in science, medicine, and industry.
Let’s take this moment to reflect on the economics of second-lightest element. Here’s to you, Helium!
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.
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.
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.