Cable Modem Turned Spectrum Analyzer

Hopefully by now most of us know better than to rent a modem from an internet service provider. Buying your own and using it is almost always an easy way to save some money, but even then these pieces of equipment won’t last forever. If you’re sitting on an older cable modem and thinking about tossing it in the garbage, there might be a way to repurpose it before it goes to the great workbench in the sky. [kc9umr] has a way of turning these devices into capable spectrum analyzers.

The spectrum analyzer feature is a crucial component of cable modems to help take advantage of the wide piece of spectrum that is available to them on the cable lines. With some of them it’s possible to access this feature directly by pointing a browser at it, but apparently some of them have a patch from the cable companies to limit access. By finding one that hasn’t had this patch applied it’s possible to access the spectrum analyzer, and once [kc9umr] attached some adapters and an antenna to his cable modem he was able to demonstrate it to great effect.

While it’s somewhat down to luck as to whether or not any given modem will grant access to this feature, for the ones that do it seems like a powerful and cheap tool. It’s agnostic to platform, so any computer on the network can access it easily, and compared to an RTL-SDR it has a wider range. There are some limitations, but for the price it can’t be beat which will cost under $50 in parts unless you happen to need two inputs like this analyzer .

Thanks to [Ezra] for the tip!

Workshop Tools Are Available In First-Class

Most of dream of having a fully-stocked shop with all of the tools needed to build our projects, at least if we don’t already have such a shop. In the meantime, a lot of us are hacking together our own tools and working on whatever bench space might be available to us. While [Emiel] aka [The Practical Engineer] has an envious shop to work from, his latest project goes to show how repurposing some aircraft-grade equipment can result in a high-quality toolbox for himself, without shelling out for any consumer-level solution. (Video, embedded below.)

The core of his workshop cart build is actually a recycled food service cart from an airline. While the original probably only housed some soft drinks and ice, this one has been kitted out to be much more functional. Since [Emiel] is using this to wheel around his machine shop, he used a CNC machine to cut out slots in black MDF sheets which would hold his drill bits, taps, and other tools. Working with MDF on a CNC machine turned out to not be as simple as he thought, since the MDF would separate and break away unless the CNC tool heads were operated in a specific way.

The build also includes several buckets for other tools, and a custom enclosure for the top of the cart specifically built for his machine tools’ tools to sit while he is working. It’s certainly a more cost-effective solution to a wheeled shop toolbox than buying something off-the-shelf, and a clever repurposing of something which would have otherwise ended up in a landfill. [Emiel] is no stranger to building any tools that he might need, including this custom belt sander built completely from the ground up.

Continue reading “Workshop Tools Are Available In First-Class”

Building A Stump Grinder From The Ground Up

Felling a tree properly is a skill that takes some practice to master, especially without causing any injuries or property damage. Getting the tree cut down though is sometimes only half of the battle, as the stump and roots need to be addressed as well. Unless you have a few years to wait for them to naturally decompose you might want to employ a stump grinder, and unless you want to spend a chunk of money on a stump grinding service or buy your own, you might want to do what [Workshop from Scratch] did and build your own.

This stump grinder isn’t anything to scoff at, either, and might even fool some into thinking it’s a consumer grade tool from a big box store. Far from it though, as almost everything down to the frame is custom machined specifically for this build. The only thing that isn’t built from scratch, including the cutting wheel, is the beefy 15 horsepower motor. Once it gets going it is able to carve stumps down to the ground in no time thanks especially to some gear reductions in the drive line from the motor to the cutting head.

Before anyone mentions safety, it looks like [Workshop from Scratch] has made some upgrades since his last project which was a gas-powered metal cutting chainsaw. Since then it looks like he has upgraded the sheet metal to something a little thicker, even though a stump grinder has arguably lower risk due to the slower speed of the cutting wheel and also to the fact that the cutting medium is wood and not metal. There are also brakes and an emergency shutoff switch. It sure seems like a fine addition to his collection of completely custom tools.

Continue reading “Building A Stump Grinder From The Ground Up”

Vintage Monochromator Makes Monochromatic Light, Mechanically

A monochromator is an optical instrument that permits only a narrow selection of wavelengths to be transmitted from a source, and the particular model [Doug] obtained renders visual light monochromatic by way of a mechanically-adjusted system of mirrors and diffraction gratings that allows only the selected wavelength to pass. The big dial is how the operator selects the desired wavelength, and is labeled in ‘mu’ (or milli-micro), but [Doug] helpfully points out the more modern term for that is nanometers.

LCD monitor viewed through a monochromator set to pass red wavelength only, showing that images remain intact.

How does it work? Light enters the device via an opening at the base, and only the selected wavelength exits from the top. The dial’s range is from 450 nm to 640 nm (representing violet-blue to red), which [Doug] demonstrates by shining a white LED flashlight into the unit and showing how only green, red, or blue will exit from the top depending on the setting of the dial.

An interesting side note is that with this particular device, images can be rendered monochromatic but otherwise remain intact. [Doug] demonstrates this by viewing a small section of his LCD monitor through the device, as shown in the photo he managed to capture.

It’s an interesting piece of vintage equipment that shows what is possible with passive optical components and a clever mechanical design. These devices are therefore entirely manually-operated tools (at least until someone sticks a stepper motor to the adjustment dial to create an automated scanner, that is.)

A 3D Printer With An Electromagnetic Tool Changer

The versatility of 3D printers is simply amazing. Capable of producing a wide variety of prototypes, miscellaneous parts, artwork, and even other 3D printers, it’s an excellent addition to any shop or makerspace. The smaller, more inexpensive printers might do one type of printing well with a single tool, but if you really want to take a 3D printer’s versatility up to the next level you may want to try one with an automatic tool changing system like this one which uses magnets.

This 3D printer from [Will Hardy] uses an electromagnet to attach the tool to the printer. The arm is able to move to the tool storage area and quickly deposit and attach various tools as it runs through the prints. A failsafe mechanism keeps the tool from falling off of the head of the printer in case of a power outage, and several other design features were included to allow others to tweak this design to their own particular needs, such as enclosing the printer and increasing or decreasing the working area of the Core-XY printer as needed.

While the project looks like it works exceptionally well, [Will] notes that it is still in the prototyping phase and needs work on the software in order to refine its operation and make it suitable for more general-purpose uses. It’s an excellent design though and shows promise. It also reminds us of this other tool-changing system we featured a few months ago, albeit with a less electromagnetic twist.

Continue reading “A 3D Printer With An Electromagnetic Tool Changer”

Adjustable, Piston-Damped Hammer

When all you have is a hammer, every problem is a constant quest for an even better hammer, as the popular saying goes. At least, that seems to be [Ebenisterie Éloïse]’s situation. She wanted a deadblow hammer that not only had an aesthetically pleasing wood and brass construction, but also one that included adjustable dampers to make sure that each hammer swing is as efficient as possible.

For those unfamiliar with specialty hammers, dead blow hammers typically have some movable mass such as sand or lead shot within the hammer head. This mass shifts forward when the hammer strikes an object, reducing rebound of the hammer off of the object and transferring more energy into each strike. This hammer omits a passive mass in favor of four custom-machined brass tubes, each of which holds a weighted fluid, a spring, and brass weight. Each piston acts as a damper in a similar way to a shock absorber on a vehicle, and a screw and o-ring at the top of each one allows them to be adjustable by adding different weight fluids as needed. Some detailed testing of the pistons shows a marked improvement over any of the passive mass varieties as well.

Not only is this an incredible amount of detail and precision for a tool that is often wielded in a non-precise way (at least among those of us for who aren’t skilled craftspeople), but it is also made out of wood, leather, and brass which gives it an improved look and feel over a plastic and fiberglass hammer that is typical of most modern deadblow hammers. It even rivals this engineer’s hammer with its intricate custom engraving in craftsmanship alone.

Continue reading “Adjustable, Piston-Damped Hammer”

CNC Scroll Saw Add-On Cuts Beautiful Wooden Spirals

If there’s one thing that woodworkers have always been good at, it’s coming up with clever jigs and work-holding solutions. Most jigs, however, are considerably simpler and more static than this CNC-controlled scroll saw add-on that makes cool wooden spirals a snap.

As interesting as the products of this setup are, what we like about this is the obvious care and craftsmanship [rschoenm] put into making what amounts to a hybrid between a scroll saw and a lathe. Scroll saws are normally used to make narrow-kerf cuts in thin, delicate materials, often with complicated designs using very tight radius turns. In this case, though, stock is held between centers on the lathe-like carriage. The jig uses a linear slide driven by a stepper and a lead screw to translate the workpiece perpendicular to the scroll saw blade while a geared headstock rotates it. Starting with the blade inserted into a through-hole, the saw slowly cuts a beautiful nested spiral down the length of the workpiece. An Uno, a GRBL shield, and some stepper drivers let a little G-code control the two axes of the jig.

The video below shows it in action; things do get a bit wobbly as the cut progresses, but in general the jig works wonderfully and results in some lovely pieces. At first we thought these would purely be objets d’art, but then we thought about this compression screw grinder for DIY injection molding machines and realized these wooden screws look pretty similar.

Continue reading “CNC Scroll Saw Add-On Cuts Beautiful Wooden Spirals”