Mini Injector

A < 50$ injection moulding machine which can be built in less than two hours.

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The Mini Injector is a small addon for a drill press that enables you to try out injection moulding on a low budget. It it makes the process of recycling plastic waste accessible to everyone who wants to learn about it.


For questions about the machine or the process and new iterations check our forum:!forum/mini-injector

  • The Mini Injector - Start

    friedrich.kegel09/27/2020 at 09:11 0 comments

    Project Intention

    The project was born within my volunteering research work over at Precious Plastic. I have found that many users of the Precious Plastic v3 injection machine only used their devices on an irregular base or just want to get their hands on for the first time to try the process themself. The v3 design is a very solid and reliable machine for injection moulding of small to mid size plastic parts.

    I was wondering if there is a less material, money and space consuming way to get started with injection molding and recycling plastic waste? What would it need to enable every curious person to recycle their own plastic waste in their home shop?

    How an injection moulding machine could look like on the very minimal specification?

    While researching many available designs which where developed over the last decades, I got inspired from "Build a Plastic Injection Molding Attachment for a Drill Press" by Vincent R. Gingery. While this design is very similar to my principle, it is not as easy to replicate due the need of less accessible machining tools:

    On the other side there are commerical solutions like the Model 20A from LNS Technologies at a price point where it may become less interesting to get started for many people.

    What was the raw principle both machines follow, and how could it become more acessible using available standard parts from a hardware store?

    Machine Design

    An injection moulding machine is a very simple device which uses pressure and temperature to push a polymer into a negative geometry (cavity) which shapes the final product. The use of injection molding for part manufacturing is faster than common 3D printing, while the post processing can be reduced to a minimum.

    The project formed mainly around the design goal of accessibility. The speed of the operation was moved to the background, due the focus on the user that wants to learn the process.

    • Accessibility by:
      • reducing the necessary machining
      • using stanard parts as far as possible
      • only use parts that are available to private customers
      • utilizing available tools in most home shops
    • Reasonable part sizes and volumes possible
    • Safety while operating
    • Usability

    Project Goals 

    Injection molding is a common process made for mass production. Mold making became more accessible with the cost reduction of CNC mills and the development of heat resistant SLA resins. Molds for prototyping can be 3D printed or casted in special resins. 

    So the evolution of injection molding towards a lower entry barrier makes sense to connect the processes of 3D printing with processes supposed for mass manufacturing.  

    Beside offering an accesible tool this project is supposed to raise awareness on the topic of plastic recycling. So we encourage everyone to use their existing plastic waste as a material source!

    This tool is especially useful for educational contexts in schools and universities, as well as for hobby use and prototype manufacturing.

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