Edge Lit Pendant, Is, Well… Lit

Acrylic is a great material. It’s not cheap, but it comes in a wide variety of colours and styles and can be used to make some very attractive projects. [Geek Mom Projects] is a big fan, and whipped up some fun pendants for a high school Maker Faire.

[Geek Mom] has long been a fan of edge-lighting, as it’s a great way to make beautiful glowy projects out of acrylic. In this case a fluorescent acrylic is used with white LEDs to generate an eerie green glow, though it’s also noted that the project can be done with clear acrylic and color-shifting LEDs instead for an equally cool look. If you’re filming a low-budget sci-fi film, this could be just what you need.

The pendants made a great project for young makers to learn about LEDs, electronics, and technologies such as lasercutting that were used to produce the parts. With copper tape used instead of soldering and a CR2032 battery used to eliminate the need for a current limiting resistor, it’s a very accessible project that most teens were able to complete without assistance.

It’s not the first time we’ve seen edge-lit pendants, either. Alternatively, if you need your acrylic bent, there’s a tool for that, too.

Get Your Acrylic Bends Just Right

Acrylic is a popular material. It’s easy to find, attractive, and available in all manner of colors, thicknesses, and grades. Being a thermoplastic, it’s also simple to apply heat and form it in various different ways. If you’re wanting to build parts out of sheet acrylic, you might find a purpose-built bender useful. [DIY Perspective] built just such a tool to get the job done.

Plywood is used as the base of the tool, and several off-the-shelf hinges are used to make the folding apparatus. Stops are cut out of scrap wood to allow the bender to accurately recreate angles of 45, 90, and 135 degrees. Heat is supplied via a nichrome wire, powered by a laptop power supply and a PWM controller. This allows the temperature of the wire to be controlled, to avoid melting or otherwise damaging the acrylic being bent.

If you find yourself routinely working with acrylic, you might find this tool useful to have around the workshop. Vacuum forming may also be relevant to your interests. Video after the break.

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Building An Artisanal Tape Measure

Some tools are so common, so basic, that we take them for granted. A perfect example is the lowly tape measure. We’ve probably all got a few of these kicking around the lab, and they aren’t exactly the kind of thing you give a lot of thought to when you’re using them. But while most of us might not give our tape measure a second thought, [Ariel Yahni] decided to create an absolutely gorgeous new enclosure for his. Because if you’re going to measure something, why not look good doing it?

A CNC router is used to carve the body of the new tape measure out of a solid block of wood and cut a top plate out of clear acrylic. [Ariel] then used an angle grinder to cut off a small section of steel rod which he secured into a carved pocket in the base using epoxy. Finally, the internals of a commercial tape measure were inserted into this new enclosure, and the acrylic top was screwed down into place.

[Ariel] has made the DXF files for this project public for anyone else who wants to carve out their own heirloom tape measure, though it seems likely the designs will need some tweaking depending on the make and model of donor tape measure. While this might not be the most technically impressive project to run on Hackaday, it’s still a fantastic example of the sort of bespoke designs that are made possible with modern manufacturing methods.

This design reminds us of a similar project to turn a basic Honda key fob into a true conversation piece with the addition of some CNC’d hardwood and aluminum.

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Plastics: Acrylic

If anything ends up on the beds of hobbyist-grade laser cutters more often than birch plywood, it’s probably sheets of acrylic. There’s something strangely satisfying about watching a laser beam trace over a sheet of the crystal-clear stuff, vaporizing a hairs-breadth line while it goes, and (hopefully) leaving a flame-polished cut in its wake.

Acrylic, more properly known as poly(methyl methacrylate) or PMMA, is a wonder material that helped win a war before being developed for peacetime use. It has some interesting chemistry and properties that position it well for use in the home shop as everything from simple enclosures to laser-cut parts like gears and sprockets.

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Behold The WT-220: A ‘Clever’ VT-220 Terminal

[John Whittington] failed to win a bid for an old VT-220 serial terminal on eBay, so he decided to make his own version and improve it along the way. The result is the Whitterm-220 (or WT-220) which has at its core a Raspberry Pi and is therefore capable of more than just acting as a ‘dumb’ serial terminal.

Rear of the WT-220 with paint-filled laser engraving and all necessary connectors.

The enclosure is made from stacked panels of laser-cut plywood with an acrylic plate on the back for labels and connectors, where [John] worked paint into the label engravings before peeling off the acrylic’s protective film. By applying paint after laser-engraving but before peeling off the film, it acts as a fill and really makes the text pop.

Near the front, one layer of clear acrylic among the plywood layers acts as a light guide and serves as a power indicator, also doing double duty as TX/RX activity lights. When power is on, that layer glows, serving as an attractive indicator that doesn’t interfere with looking at the screen. When data is sent or received, a simple buffer circuit tied to the serial lines lights up LEDs to show TX or RX activity, with the ability to enable or disable this functionality by toggling a GPIO pin. A video overview is embedded below, where you can see the unit in action.

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Scratch-Building A Supersized Laser Cutter

Now that 3D printers have more or less hit the mass market, hackers need a new “elite” tool to spend their time designing and fiddling with. Judging by the last couple of years, it looks like laser cutters will be taking over as the hacker tool du jour; as we’re starting to see more and more custom builds and modifications of entry-level commercial models. Usually these are limited to relatively small and low powered diode lasers, but as the following project shows, that’s not always the case.

This large format laser cutter designed and built by [Rob Chesney] is meticulously detailed on his blog, as well as in the in the video after the break. It’s made up of aluminium profile and a splattering of ABS 3D printed parts, and lives in an acrylic enclosure that’s uniquely isolated from the laser’s internal gantry. All told it cost about $2,000 USD to build, but considering the volume and features of this cutter that’s still a very fair price.

[Rob] carefully planned every aspect of this build, modeling the entire machine in CAD before actually purchasing any hardware. Interestingly enough his primary design constraint was the door to his shed: he wanted to build the largest possible laser cutter that could still be carried through it. That led to the final machine’s long and relatively shallow final dimensions. The design was also guided by a desire to minimize material waste, so when possible parts were designed to maximize how many could be cut from a one meter length of aluminum extrusion.

The laser features a movable Z axis that’s similar in design to what you might see in a Prusa-style 3D printer, with each corner of the gantry getting an 8 mm lead screw and smooth rod which are used in conjunction to lift and guide. All of the lead screws are connected to each other via pulleys and standard GT2 belt, but as of this version, [Rob] notes the Z axis must be manually operated. In the future he’ll be able to add in a stepper motor and automate it easily, but it wasn’t critical to get the machine running.

He used 3D printed parts for objects which had a relatively complex geometry, such as the laser tube holders and Z axis components, but more simplistic brackets were made out of cut acrylic. In some components, [Rob] used welding cement to bond two pieces of acrylic and thereby double the thickness. Large acrylic panels were also used for the laser’s outer enclosure, which was intentionally designed as a separate entity from the laser itself. He reasoned that this would make assembly easier and faster, as the enclosure would not have to be held to the same dimensional tolerances as it would have been if it was integrated into the machine.

[Rob] gives plenty of detail about all the finer points of water cooling, laser control electronics, aligning the mirrors, and really anything else you could possibly want to know about building your own serious laser cutter. If you’ve been considering building your own laser and have anything you’re curious or unsure about, there’s a good chance he addresses it in this build.

Short of having the fantastically good luck to find a laser cutter in the trash that you can refurbish, building your own machine may still be the best upgrade path if you outgrow your eBay K40.

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SandBot Happily And Tirelessly Rolls Patterns In Sand

The patience and precision involved with drawing geometric patterns in sand is right up a robot’s alley, and demonstrating this is [rob dobson]’s SandBot, a robot that draws patterns thanks to an arm with a magnetically coupled ball.

SandBot, SCARA version. The device sits underneath a sand bed, and a magnet (seen at the very top at the end of the folded “arm”) moves a ball bearing through sand.

SandBot is not a cartesian XY design. An XY frame would need to be at least as big as the sand table itself, but a SCARA arm can be much more compact. Sandbot also makes heavy use of 3D printing and laser-cut acrylic pieces, with no need of an external frame.

[rob]’s writeup is chock full of excellent detail and illustrations, and makes an excellent read. His previous SandBot design is also worth checking out, as it contains all kinds of practical details like what size of ball bearing is best for drawing in fine sand (between 15 and 20 mm diameter, it turns out. Too small and motion is jerky as the ball catches on sand grains, and too large and there is noticeable lag in movement.) Design files for the SCARA SandBot are on GitHub but [rob] has handy links to everything in his writeup for easy reference.

Sand and robots (or any moving parts) aren’t exactly a natural combination, but that hasn’t stopped anyone. We’ve seen Clearwalker stride along the beach, and the Sand Drawing Robot lowers an appendage to carve out messages in the sand while rolling along.