Casting Machine Bases in Composite Epoxy

When you’re building a machine that needs to be accurate, you need to give it a nice solid base. A good base can lend strength to the machine to ensure its motions are accurate, as well as aid in damping vibrations that would impede performance. The problem is, it can be difficult to find a material that is both stiff and strong, and also a good damper of vibrations. Steel? Very stiff, very strong, terrible damper. Rubber? Great damper, strength leaves something to be desired. [Adam Bender] wanted to something strong that also damped vibrations, so developed a composite epoxy machine base.

[Adam] first takes us through the theory, referring to a graph of common materials showing loss coefficient plotted against stiffness. Once the theory is understood, [Adam] sets out to create a composite material with the best of both worlds – combining an aluminium base for stiffness and strength, with epoxy composite as a damper. It’s here where [Adam] begins experimenting, mixing the epoxy with sand, gravel, iron oxide and dyes, trying to find a mixture that casts easily with a good surface finish and minimum porosity.

With a mixture chosen, it’s then a matter of assembling the final mould, coating with release agent, and pouring in the mixture. The final result is impressive and a testament to [Adam]’s experimental process.

We’ve seen similar builds before — like this precision CNC built with epoxy granite — but detail in the documentation here is phenomenal.

A Wireless Oscilloscope Isn’t As Dumb As It Sounds

The latest CrowdSupply campaign is a wireless, Bluetooth oscilloscope that doesn’t make a whole lot of sense until you really think about it. Once you get it, the Aeroscope wireless oscilloscope is actually a pretty neat idea.

If the idea of battery-powered, Bluetooth-enabled test and measurement gear sounds familiar, you’re not dreaming. The Mooshimeter, also a project on CrowdSupply, is a multichannel multimeter with no buttons, no dial, and no display. You use the Mooshimeter through an app on your phone. This sounds like a dumb idea initially, but if you want to measure the current consumption of a drone, or under the hood of your car while you’re driving, it’s a really, really great idea.

The specs of the Aeroscope aren’t bad for the price. It is, of course, a one-channel scope with 20 MHz bandwidth and 100Msps. Connection to the device under test is through pokey bits or grabby bits that screw into an SMA connector, and connection to a display is over Bluetooth 4.0. You’re not getting a scope that costs as much as a car here, but you wouldn’t want to put that scope in the engine bay of your car, either.

The Aeroscope is currently on CrowdSupply for $200. Compared to the alternatives, that’s a bit more than the no-name, USB scopes. Then again, those are USB scopes, not a wireless, Bluetooth-enabled tool, and we can’t wait to see what kind of work this thing enables.

Electric Arc Furnace Closes the Loop

When we think of an Electric Arc Furnace (EAF), the image that comes to mind is one of a huge machine devouring megawatts of electricity while turning recycled metal into liquid. [Gregory Hildstrom] did some work to shrink one of those machines down to a practical home version. [Greg] is building on work done by [Grant Thompson], aka “The King of Random” and AvE. Industrial EAFs are computer controlled devices, carefully lowering a consumable carbon electrode into the steel melt. This machine brings those features to the home gamer.

[Greg] started by TIG welding up an aluminum frame. There isn’t a whole lot of force on the Z-axis of the arc furnace, so he used a stepper and lead screw arrangement similar to those used in 3D printers. An Adafruit stepper motor shield sits on an Arduino Uno to control the beast. The Arduino reads the voltage across the arc and adjusts the electrode height accordingly.

The arc behind this arc furnace comes from a 240 volt welder. That’s where [Greg] ran into some trouble. Welders are rated by their duty cycle. Duty cycle is the percentage of time they can continuously weld during a ten minute period. A 30% duty cycle welder can only weld for three minutes before needing seven minutes of cooling time. An electric arc furnace requires a 100% duty cycle welder, as melting a few pounds of steel takes time. [Greg] went through a few different welder models before he found one which could handle the stress.

In the end [Greg] was able to melt and boil a few pounds of steel before the main 240 V breaker on his house overheated and popped. The arc furnace might be asking a bit much of household grade electrical equipment.

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Roam the Wastelands with this Fallout-Themed Mini Geiger Counter

For anyone who has worked with radioactive materials, there’s something that’s oddly comforting about the random clicks of a Geiger counter. And those comforting clicks are exactly why we like this simple pocket Geiger counter.

Another good reason to like [Tim]’s build is the Fallout theme of the case. While not an item from the game, the aesthetic he went for with the 3D-printed case certainly matches the Fallout universe. The counter itself is based on the popular Russian SBT-11A G-M tubes that are floating around eBay these days. You might recall them from coverage of this minimalist Geiger counter, and if you were inspired to buy a few of the tubes, here’s your chance for a more polished build. The case is stuffed with a LiPo pack, HV supply, and a small audio amp to drive the speaker. The video below shows it clicking merrily from a calibration source.

We can see how this project could be easily expanded — a small display that can show the counts per minute would be a great addition. But there’s something about how pocketable this is, and just the clicking alone is enough for us.

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How An Oscilloscope Probe Works, And Other Stories

The oscilloscope is probably the most versatile piece of test equipment you can have on your electronics bench, offering a multitude of possibilities for measuring timing, frequency and voltage as well as subtleties in your circuits revealed by the shape of the waveforms they produce.

On the front of a modern ‘scope is a BNC socket, into which you can feed your signal to be investigated. If however you simply hook up a co-axial BNC lead between source and ‘scope, you’ll immediately notice some problems. Your waveforms will be distorted. In the simplest terms your square waves will no longer be square.

Why is this? Crucial to the operation of an oscilloscope is a very high input impedance, to minimise current draw on the circuit it is investigating. Thus the first thing that you will find behind that BNC socket is a 1 megohm resistor to ground, or at least if not a physical resistor then other circuitry that presents its equivalent. This high resistance does its job of presenting a high impedance to the outside world, but comes with a penalty. Because of its high value, the effects of even a small external capacitance can be enough to create a surprisingly effective low or high pass filter, which in turn can distort the waveform you expect on the screen.

The answer to this problem is to be found in your oscilloscope probe. It might seem that the probe is simply a plug with a bit of wire to a rigid point with an earth clip, but in reality it contains a simple yet clever mitigation of the capacitance problem.

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Laser Cutting a 3D Printer

The concept of self-replicating 3D printers is a really powerful one. But in practice, there are issues with the availability and quality of the 3D-printed parts. [Noyan] is taking a different approach by boostrapping a 3D printer with laser-cut parts. There are zero 3D-printed parts in this project. [Noyan] is using acrylic for the frame and the connecting mechanisms that go into the machine.

The printer design chosen for the project is the Prusa i3. We have certainly seen custom builds of this popular design before using laser-cut plywood for the frame. Still, these builds use 3D-printed parts for some of the more complicated parts like the extruder carriage and motor brackets. To the right is the X-carriage mechanism. It is complicated but requires no more than 6 mm and 3 mm acrylic stock and the type of hardware traditionally associated with printer builds.

With the proof of concept done, a few upgrades were designed and printed to take the place of the X-axis parts and the belt tensioner. But hey, who doesn’t get their hands on a 3D printer and immediately look for printable solutions for better performance?

We first saw a laser-cut RepRap almost nine years ago! That kit was going to run you an estimated $380. [Noyan] prices this one out at under $200 (if you know someone with a laser cutter), and of course you can get a consumer 3D printer at that price point now. Time has been good to this tool.

Keysight’s New 1000-X Scopes Get Double Hertz

It’s not every day that we have the pleasure of being excited about a new oscilloscope in the market; not only is it affordable but also produced by one of the industry’s big players. To top it all off,  all the marketing is carefully crafted towards students and hackers.

Keysight recently released a new line of oscilloscopes called the 1000X series that starts at $448. It’s an entry level, two-channel scope having (officially) 50 MHz, 70 MHz and 100 MHz versions to choose from. It hosts their standard technology such as Megazoom, but also some interesting, albeit optional extra quirks such as an in-built signal generator and a simple network analyser with gain and phase plot capability.

The release of this scope and the marketing strategy employed by Keysight feels like they’re late to this entry-level party but still want to get in on the fun. In the words of Keysight we should all immediately “Scrap the toys, get a real oscilloscope” . The persuasion has gone a step further; Keysight has kindly facilitated many giveaways and generated hype from our favorite EE YouTuber’sIf anything, this certainly heats up the entry level scope market, so we at Hackaday welcome it with open arms.

All this fuss about affordable yet capable entry level scopes started with Rigol. Here was a company that actually bothered to genuinely market a scope to the masses at a reasonable price. At the time, the norm for such scopes was to be marketed solely to schools and universities by large teams of suits. Winning the hearts (and money) of any hackers along the way was merely collateral damage.  The scope that considerably changed this was the Rigol DS1052e, the predecessor of the DS1054z which is now considered the benchmark for all entry level scopes. If Keysight is to entice us to scrap the toys, the 1000X series must spar with the community’s current sweetheart.

It is still early days for this scope, but [Dave Jones] already received one and successfully unlocked the shipped bandwidth lock. He has even unearthed an undocumented 200 MHz bandwidth mode by hacking the main processor board! Unsurprisingly, the analog front end is consistent across all the models with the sampling rate and bandwidth being set, rather old-fashionedly, by a few resistors on the main processor board.

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