Injection Molding With A Hot Glue Gun

Injection molding is an industrial process used the world over for the quick and economical production of plastic parts. [Nikodem Bartnik] wanted to experiment with this at home, so whipped up some molds and got to work (Youtube link, embedded below).

[Nikodem] produced aluminium molds, using a Dremel-based CNC platform. This allowed for the design to be created in CAD software, and helps with the production of the geometry for both the part, as well as the gates and vents. Having learned about thermal issues with an early attempt, the mold was then clamped in a vice. Wood was used as an insulator to minimise heat lost to the vice.

With this setup, it was possible to mold M5 washers using hot glue, with good surface finish. Later attempts with a larger mold were unsuccessful, due to the glue cooling off before making it through the entire mold. [Nikodem] has resolved to improve his setup, and we look forward to seeing what happens next. We’ve seen others experiment in this area before, too. Video after the break.

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Hot Glue Makes These Segments Glow

It’s safe to say that hot-melt glue is a staple of the projects we see here at Hackaday. There won’t be many readers who don’t have a glue gun, and a blob of the sticky stuff will secure many a project. But it’s not so often we see it used as an integral component for a property other than its stickiness, so [DusteD]’s reaction timer project is interesting for having hot glue as a translucent light guide and diffuser for its LED seven-segment display.

The timer is simple enough, being driven by an Arduino board, while the display is pre-formed into the 3D-printed case. The hot glue fills the enclosures behind each segment, and after several experiments it was found that the best filling method was from behind against a piece of Kapton tape. The LEDs were wired into a common cathode array, and along with the arcade-style button and the Arduino the whole fitted neatly in the box. You can see the result in action in the video below the break.

Of course, this display is unusual for its use of hot glue, but not unique. We’ve seen a different take on a hot glue light pipe display before.

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Let There Be Light Rings!

[Brandon Rice] is at it again — this time to level-up your photography and video production skills with a diffused light ring.

Inspired into creating more video content, he wanted to forgo the price tag associated with consumer lighting rigs. A 19″ diameter ring fit his requirements, but since the only laser cutter he had access to was limited to 12″x14″, he was forced to assemble it in pieces. As he screwed it together, he hid the M6 screws by pointing them ‘forwards,’ to be hidden underneath the diffusing vellum material. Liberal application of hot glue has kept the arched vellum and the LED strips in place with only a nominal number of burned fingers.

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LEGO Based 3Doodler Uses Regular Filament

As part of a university research project, [Vimal Patel] was asked to make something out of biodegradable 3D printer filament. The theme of the project is called Monomateriality — making products out of a single material to aid the manufacturing process, and after the product is used, ease of recycling.

He started by experimenting with the 3D printer filament in the UP 3D printers the university had on hand. But he wasn’t content with the layer-by-layer deposition method that all FDM printers use. He was more curious about free form deposition modeling — extruding material along multiple axes at once.

Unfortunately the project budget didn’t afford him a 6-axis robotic arm 3D printing setup like this to complete the project. But he was able to build his own custom extruder using a hot glue gun, and some LEGO. It’s kind of like a 3Doodler, but much more bulky.

gun-revolve-culledframesUsing standard LEGO parts he was able to build an attachment for the hot glue gun to feed the 3mm diameter biodegradable filament through the nozzle. He’s uploaded the design files over at rebrickable.com to share with the world.

While the end product he designed (a bicycle helmet) isn’t too realistic, [Vimal’s] more excited at the accessibility of the making process — after all, you just need a hot glue gun and some LEGO.

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PID Controlled Glue Gun

Internals of a glue gun controlled with a PID controller

Hot glue falls into the same category of duct tape and zip ties as a versatile material for fixing anything that needs to be stuck together. [Ed]’s Bosch glue gun served him well, but after a couple of years the temperature regulation stopped working. Rather than buying a new one, he decided to rip it apart.

With the old temperature regulation circuit cooked, [Ed] looked around for something better on eBay. He came across a cheap PID temperature controller, and the Frankengluegun was born.

A thermocouple, affixed with some kapton tape and thermal paste, was used to measure the temperature of the barrel. Power for the glue gun was routed through the PID controller, which uses PWM to accurately controller the temperature. All the wiring could even be routed through the original cord grips for a clean build.

Quality glue guns with accurate temperature control are quite pricey. This solution can be added on to a glue gun for less than $30, and the final product looks just as good.

Using Surface Mount Devices On A Breadboard

[Czar] was working on a project with the Raspberry Pi using the MCP3008 analog to digital converter. The surface mount SOIC version of this chip was slightly cheaper, and there’s always a way to make that work (Portuguese, Google Translation). How [Czar] did it is fairly impressive, as it’s a bit more flexible for breadboard designs than a through-hole version, and done correctly, is an extremely sturdy hack.

A few new leads needed to be soldered onto the SOIC package, and for this [Czar] chose jumper wires. This makes each pin easy to plug into a solderless breadboard, and since [Czar] was extremely clever, all the wires for power, ground, analog, and SPI are color coded.

Simply soldering a few jumper wires onto a chip won’t last for very long. To solve this problem, [Czar] potted the entire chip and its connections with hot glue. Probably not the best solution, and a heavy-duty epoxy would have been better, but the current build is more than enough to stand up to the relatively minor abuse it will receive on the workbench.

Injection Molding With Hot Glue

Injection molding is simply forcing a melted thermoplastic into a mold of some sort, letting it cool, and then prying the mold apart to get to the finished piece. Hot glue guns are basically handheld thermoplastic extruders, so when [scorch] dug up some old injection molds he had sitting around, it didn’t take long to put two and two together.

Injection molds aren’t something any normal person has sitting around, but a few years ago [scorch] found two books published by Gingery, the same people who have published instructions on how to build a metalshop from scrap. [scorch] created his molds on a small CNC mill – a Sieg X3 – and his initial experiments with injection molded plastic were fairly successful, even if the molds were made from self-cast billets.

After molding a few hot glue LEGO parts with his equipment, [scorch] had a look around the Internet and noticed this was nothing new. One company even sells a hot glue gun-based injection molding kit using polyethylene glue sticks. Their demo video (seen below) seems much more complicated than [scorch]’s efforts, so  we’ll say he came out ahead on this one.

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