DIY Injection Mold Design For The Home Shop

3D printing is great for prototyping, and not bad for limited runs of parts. Unfortunately though it really doesn’t scale well beyond a few pieces, so when you’re ready for the mass market you will need to think about injection molding your parts. But something like that has to be farmed out, right? Maybe not, if you know a thing or two about designing your own injection molds.

The video below comes from [Dave Hakkens] by way of his Precious Plastic project, whose mission it is to put the means of plastic recycling into the hands of individuals, rather than relying on municipal programs.  We’ve covered their work before, and it looks like they’ve come quite a way to realizing that dream. This tutorial by [Dave]’s colleague [Jerry] covers the basic elements of injection mold design, starting with 3D modeling in Solidworks. [Jerry] points out the limitations of a DIY injection molding effort, including how the thickness of parts relates to injection pressure. Also important are features like gentle curves to reduce machining effort, leaving proper draft angles on sprues, and designing the part to ease release from the mold. [Jerry] and [Dave] farmed out the machining of this mold, but there’s no reason a fairly complex mold couldn’t be produced by the home gamer.

When you’re done learning about mold design, you’ll be itching to build your own injection mold machine. Precious Plastic’s tutorial looks dead simple, but this machine looks a little more capable. And why CNC your molds when you can just 3D print them?

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Think Globally, Build Locally With These Open-Source Recycling Machines

Walk on almost any beach or look on the side of most roads and you’ll see the bottles, bags, and cast-off scraps of a polymeric alphabet soup – HDPE, PET, ABS, PP, PS. Municipal recycling programs might help, but what would really solve the problem would be decentralized recycling, and these open-source plastics recycling machines might just jump-start that effort.

We looked at [Precious Plastic] two years back, and their open-source plans for small-scale plastic recycling machines have come a long way since then. They currently include a shredder, a compression molder, an injection molder, and a filament extruder. The plans specify some parts that need to be custom fabricated, like the shredder’s laser-cut stainless steel teeth, but most can be harvested from a scrapyard. As you can see from the videos after the break, metal and electrical fabrication skills are assumed, but the builds are well within the reach of most hackers. Plans for more machines are in the works, and there’s plenty of room to expand and improve upon the designs.

We think [Precious Plastic] is onto something here. Maybe a lot of small recyclers is a better approach than huge municipal efforts, which don’t seem to be doing much to help.  Decentralized recycling can create markets that large-scale manufacturing can’t be bothered to tap, especially in the developing world. After all, we’ve already seen a plastic recycling factory built from recycled parts making cool stuff in Brazil.

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Multiple Material 3D Printing

It’s no surprise that we’re wild about 3D printing, especially [Devlin]. Now we’re absolutely out of our minds for this multi-material polyjet machine that is featured in the video above. Before we go any further it’s worth mentioning that this post is not advertising, we just think this machine is unbelievable.

It is capable of printing 600 dpi in 3D using multiple materials at the same. Two types of rigid material, one like ABS and the other like polypropylene, as well as seven levels of a soft material all exist on the same print head. They can be deposited along with a support material at the same time. In the video you can see enclosures that come out of the printer with rubber-like padding already mounted in the hard plastic shell. They even show a bicycle chain that is fully assembled after printing. Cost for these machines? We don’t want to know, it’s just fun to dream about having unrestricted access to one.

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DIY Mood Lamp Looks Store-bought

[NeZoomie] built an RGB mood lamp as his first electronics project. He certainly hit it out of the park with this one, ending up with a design so clean it could be a commercial product. The controller is an Arduino board (further proof that this is a fantastic entry-level platform) that interfaces with 8 RGB LEDs. He’s built an enclosure out of thick polypropylene that does a great job of diffusing the light and adding a stylish look. The control system features a rotary potentiometer from SparkFun and what he calls a tilt-potentiometer of his own design after drawing inspiration from Hack a Day.

Blinky things are fun and that’s why we see a lot of mood lamps around here. Take a look at the video after the break and if you’ve got the parts, give this one a try!

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