Frank Makes A CNC Table

[Frank Howarth] is one of the big guns when it comes to woodworking on YouTube, and now he’s doing something completely unlike his other builds. He’s building a gigantic CNC machine. Yes, we’ve seen dozens of CNC router builds, but this one adds a few nifty features we’ve never seen before.

The plans for [Frank]’s CNC machine call for a 4 foot by 8 foot table, over which a router on a gantry gnaws away at wood. This is the standard size for shop-sized CNC router, but [Frank] is adding in his own twist: he’s building a 12 foot long table, by way of a four foot extension. This one small addition allows [Frank] to put tenons in tree trunks, engravings on the side of furniture, or just to make one part of a very large piece flat.

Right now, the build is just about the base, constructed out of 2″ square steel tube. While the welding is by all accounts an amateur job, everything is square, straight, and true. Now, with a metal base scooting around on hockey puck feet, [Frank] is ready to start on the robotic part of the build, something we’re all interested to see.

It’s going to be really big, but still not the biggest.

Retrotechtacular: So You Want to Be a Weldor

Welding is one of those things that takes minutes to learn and years to master. It requires coordination, strength, and a good pair of eyes. This vocational guidance video from the early 1940s touches on these points and more for those considering careers in welding. The narrator jumps right in, discussing welding types, equipment operation, and employment opportunities in both the welding field itself and other fields that use welding techniques.

Oxy-acetylene welding is one of the oldest methods of fusing metal. A flame fueled by a specific mixture of pure oxygen and acetylene gas heats the metal welding rod and the work piece to plasticity, which allows them to join together. An oxy-acetylene setup can also be used to cut metal, though a special cutting torch with a kind of oxygen turbo boost lever is required. The work piece is heated to red-hot at the point along the edge where the cut will start. The oxygen-rich flame will cut right through the piece.

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Hacker Creates Thermal Probes by Welding with a PC Power Supply

[Illya Tsemenko] decided to build his own thermocouples from bare wire. [Illya] is interested in measuring the temperature of Liquid Nitrogen and for this he needed T-type probes. While you can buy these for about 20 bucks, he felt this was too expensive for what is essentially two pieces of wire and decided to build his own.

Thermocouples use the Seebeck effect, when a piece of metal is hot at one end, and cold at the other the electrons in the hot end will be more energetic and migrate towards the cold end, creating a voltage. While this migration occurs in single metal, it can’t easily be measured (as the voltage will be the same as the measurement point). For that reason thermocouples use two metals in which the migration occurs at different rates. This difference creates an overall migration in one direction, and a voltage can be measured which correlates to the temperature where the metals meet. Thermocouples are extremely common and have many applications.

In order to make his thermocouples [Illya] needed to weld the two metals together, and knocked together a quick welding rig using a PC power supply and graphite electrode from a powertool. The graphite electrode is important as it prevents oxidization during the welding process.

The process worked well, and [Illya] was able to make both K and T-type thermocouples and successfully measure temperatures down to -190 degrees C. Awesome work [Illya]!

Polarization Camera Views the Invisible

Light polarization is an interesting phenomenon that is extremely useful in many situations… but human eyes are blind to detecting any polarization. Luckily, [David] has built a polarization-sensitive camera using a Raspberry Pi and a few off-the-shelf components that allows anyone to view polarization. [David] lists the applications as:

A polarimetric imager to detect invisible pollutants, locate landmines, identify cancerous tissues, and maybe even observe cloaked UFOs!

The build uses a standard Raspberry Pi 2 and a 5 megapixel camera which sits behind a software-controlled electro-optic polarization modulator that was scavenged from an auto-darkening welding mask. The mask is essentially a specialized LCD screen, which is easily electronically controlled. [David] whipped up some scripts on the Pi that control the screen, which is how the camera is able to view various polarizations of light. Since the polarization modulator is software-controlled, light from essentially any angle can be analyzed in any way via the computer.

There is a huge amount of information about this project on the project site, as well as on the project’s official blog. There have been other projects that use polarized light for specific applications, but this is the first we’ve seen of a software-controlled polarizing camera intended for general use that could be made by pretty much anyone.

The 2015 Hackaday Prize is sponsored by:

Field Expedient Stick Welder from Cordless Tool Battery Packs

The self-proclaimed and actual “smartest idiot on YouTube” is back with another entry from the “don’t try this at home” file. [AvE] recently did a teardown of a new DeWalt cordless drill-driver, and after managing to get everything back together, he was challenged by a viewer to repurpose the 20V battery packs into an impromptu stick welder.

AvE_short[AvE] delivered – sort of. His first attempt was with the two battery packs in parallel for higher current, but he had trouble striking an arc with the 1/8″ rod he was using. A freeze-frame revealed an incredible 160A of short-circuit current and a welding rod approaching the point of turning into plasma. Switching to series mode, [AvE] was able to strike a reasonable arc and eventually lay down a single splattery tack weld, which honestly looks better than some of our MIG welds. Eventually his rig released the blue smoke, and the postmortem teardown of the defunct packs was both entertaining and educational.

While we can’t recommend destroying $100 worth of lithium-ion battery packs for a single tack weld, it’s interesting to see how much power you’re holding in the palm of your hand with one of these cordless drills. We saw a similar technique a few years back in a slightly more sophisticated build; sadly, the YouTube video in that post isn’t active anymore. But you can always stay tuned after the break for the original [AvE] DeWalt teardown, wherein blue smoke of a different nature is released.

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Give me a Welder and Rod Stock and I’ll Build you the World

Metal fabrication is a an art that often goes under appreciated. The ability to take common stock in the form of sheet, pipe (square or round), and in this case rod, and make it into anything is intoxicating for the artist and super villain inside of each of us. Recently [asciiArtVandaly] took on an interesting job and was thoughtful enough to make a photo album of the process. He literally created the world out of metal.

The build is a wire-frame globe. The latitude and longitude rods are rolled to the proper arc, but holding them in place is a bit of a trick. This image shows the welding jig built just for this project. It has large and small nobs to match the increasing spacing of the rods, with washers holding down ever other joint. If you want to see an example of rod-rolling check out the unrelated How It’s Made segment found after the break.

This jig is visually stunning to look at, but the math used to lay something like this out is only mildly interesting compared to the work done to add the continents to the piece. Each of these were cut out and then hand hammered to match the curve of the globe before being welded in place and outfitted with lighting for cities. That’s a skill you can’t get without a lot of practice — and get this, [asciiArtVandalay] does it as a hobby. Who knew robot engineers needed hobbies?

The finished globe is about eighty pounds of stainless steel. The build ends up being corporate art for a company sure to turn [Tyler Durden’s] eye.

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Building a Horn Antenna for Radar

So you’ve built yourself an awesome radar system but it’s not performing as well as you had hoped. You assume this may have something to do with the tin cans you are using for antennas. The obvious next step is to design and build a horn antenna spec’d to work for your radar system. [Henrik] did exactly this as a way to improve upon his frequency modulated continuous wave radar system.

To start out, [Henrik] designed the antenna using CST software, an electromagnetic simulation program intended for this type of work. His final design consists of a horn shape with a 100mm x 85mm aperture and a length of 90mm. The software simulation showed an expected gain of 14.4dB and a beam width of 35 degrees. His old cantennas only had about 6dB with a width of around 100 degrees.

The two-dimensional components of the antenna were all cut from sheet metal. These pieces were then welded together. [Henrik] admits that his precision may be off by as much as 2mm in some cases, which will affect the performance of the antenna. A sheet of metal was also placed between the two horns in order to reduce coupling between the antennas.

[Henrik] tested his new antenna in a local football field. He found that his real life antenna did not perform quite as well as the simulation. He was able to achieve about 10dB gain with a field width of 44 degrees. It’s still a vast improvement over the cantenna design.

If you haven’t given Radar a whirl yet, check out [Greg Charvat’s] words of encouragement and then dive right in!