Repair using 3D printing

A structured process for making a 3D printed spare part

This is a series of guides and complementary tools, covering the entire process of reproducing a 3D printed substitute for a broken plastic part. Virtually anyone can recreate a broken plastic part, from for instance from a domestic appliance!

The process consists of three main steps: Decomposition, Remodeling and Reproduction, which I split up into several Instructables. This series of guides is accompanied by a set of tools, helping you with critical decisions thoughout the process!

1 Decomposition: find critical features and requirements for the new part

2 Remodeling: create a 3D model based on the original part, ready for printing

3 Reproduction: finding a printer, material and printing the spare part

It is strongly advised to follow the guides subsequently! The decomposition sets many important criteria and points out if you are either better off with 3D scanning the original part, or modelling from scratch (as this might be quicker and more accurate!).

Furthermore, I will not go into detail about the very basics of CAD modelling or 3D printing, as many resources for that already exist; the focus will be on the application of these skills.

That being said, it is time to start! Good Luck and don't hesitate to share your experiences, remarks and comments on the process!

- Thijs

This series of guides is the result of the Graduation project "Application of 3D printing in Repair" by me (Thijs Beerkens, 2017), as a concluding project for the Master's degree Integrated Product Design at Delft University of Technology, faculty of Industrial Design Engineering. They are based on the research done in the project, both findings from literature as practical experiments, to shape the process of reproduction into this series of guides and tools.

Disclaimer

This guide involves tinkering with commercially sold appliances. This voids any warranties, can possibly be hazardous and is advised to do with care and common sense! I strongly recommend you take appropriate safety precautions for the type of work that you are doing, such as wearing protective clothing and working in a designated area. With any doubts, contact an expert!
ALWAYS unplug net connected appliances before working with them, and leave them unplugged for at least 30 minutes. Some appliances contain large condensators that store large amounts of electricity and might unload on contact. Some appliances contain heat-generating components that need to cool down completely before working with them.
Be careful with self-made, 3D printed spare parts. They do not comply to the OEM’s quality standards and testing, and therefore are not guaranteed to function appropriately. Be especially careful with parts that are load-bearing, spring loaded or come in contact with heat, water and food.
The writer of this guide and any referenced sources are not responsible for anything you do in relation to this guide.

Step 1: Background Info

This guide is the introduction to a series of guides: 3D printing for Repair. As the result of my master’s thesis in Industrial Design Engineering, at Delft University of Technology, I’ve created this series of guides and complementary tools based on my research graduation project.

I studied the application of 3D printing in repair; finding limitations and possibilities in using 3D printing for the production of spare parts. In particular, I focused on consumer-sided repair; enabling people to create their own substitute for their often unique, one-time repair case. As there is an uncountable variety of products and parts, and therefore also obsolescence and scarcity of spare parts, an individual being able to print its own opens up many possibilities for the future of repair.

The scope of this project was to focus on rigid, plastic parts from domestic appliances, as these are frequently discarded products, with an increasingly shortening lifespan. Think of kitchen appliances such as electric kettles, coffee makers and microwaves, but also power tools, garden equipment and any other appliances with plastic parts. Frequently used products, prone to damage and wear and with parts that would fit inside a regular desktop 3D printer were ideal to kickstart the research on. Findings can later on be expanded to other product categories, such as toys, portable items, sports equipment etcetera.

This series of guides is put up with this general idea of being applicable to as many repair cases as possible. You are guided through the complete process of examining the original part that is in need of replacement, creating a 3D model of it and printing advice for producing a viable substitute.

This guide is intended to be used by anyone, inexperienced to advanced in 3D modeling and printing! As a result of my studies, including various attempts and experiments on repair cases, I’ve developed a streamlined process with a set of tools to help you create a spare part. It is still a rather explorative and experimental process (as is basically any DIY project), but that makes it fun and interesting, right?

Step 2: The Process

The process of reproducing a viable, 3D printed substitute for your broken part is divided into three main steps: Decomposition, Remodelling and Reproduction. I’ve summarized the process in an infographic, with the guides and tools included behind a QR code.

You can print this infographic as a poster (A1 or A3): Poster

Feel free to print it and hang it in your workspace, as it is in itself already a helpful tool to keep track and use again in the future!

Decomposition

The first guide; Decomposition, learns you to look at the original part, to set requirements for the 3D printed substitute. This is very important to do upfront! Setting important requirements, finding critical features and selecting the right modeling strategy gives you a flying start towards the actual reproduction and greatly increases the chance of success in creating a usable replacement. We will look at the part’s function and context, material and geometry to determine which aspects of it are important to reproduce accurately, and what can be simplified to speed up the process. Through this decomposition, you will also identify how the part was built up, helping you to recreate it in a 3D model.

Remodelling

Next, as an outcome of the Decomposition, you will have either selected CAD modeling or 3D scanning as a preferred strategy. Based on a thorough decomposition of the original part, you’ll see that some parts are easily modeled (even by inexperienced modelers), where some are better 3D scanned due to their complexity and curved shapes. I’ve written a guide for both Remodeling Tracks: the CAD modeling guide will help you take measurements and references and apply them in 3D modeling, the 3D scanning guide entails a full process for photogrammetry-based 3D scanning using a digital camera and software to create detailed 3D scans!

Reproduction

After you’ve created the 3D model, the reproduction guide helps you to prepare it for printing and print it! I’ve included several useful platforms for finding a 3D printer or service nearby, as there are more 3D printers already available to you than you might think! 3D printing at a local printer or on someone else’s printer is often not expensive either; you’ve created the model yourself already, so only material and electricity and possibly a small fee for starting the printer are charged. For your reference, a kilogram of common PLA filament costs about 20 euros; weigh your part and find that it probably costs a fraction of that!

Step 3: What Kind of Part Are Eligible for Reproduction?

Since 3D printing at the moment is mainly plastic-based, I focused on reproducing rigid, plastic parts in the first place. But of course, you can reproduce parts originally made from other materials, such as wood or metal, but in a 3D printed plastic. Beware of the requirements set for such a part (as you will discover in the Decomposition, as a reproduction in a different material will perform differently. Furthermore, most of the common 3D printing plastics are rigid or only marginally flexible, so highly flexible parts are difficult to recreate as well.

Lastly, look at the size of the part in question. If it takes up a significant part of the whole product, requiring you to take the whole thing apart, it will be a difficult job. Also, the part has to fit within the build envelope of a 3D printer, as it can otherwise not be printed in true scale. Unfortunately, this is one of the main limitations in 3D printing at the moment, as larger prints take up significantly more time than smaller ones, obviously. A common build envelope for desktop 3D printers today is around 200 x 200 x 200 mm, but bigger and mainly taller printers exist. It is however sensible to stick to this size for now, as this ensures that you can print on widely available printers.

Step 4: What You Need

So, what do you need to make your own spare part? Well, the very least is the original part that needs replacement. This part is ideally complete for most part, but it is not uncommon that you lost bits of it when it broke. It might be missing entirely, as well. The most important aspect of having the original part is that you have a reference to work from! You will be taking measurements and photographs of it, so it is helpful to have it around and complete. But; the rest of the product it came from also tells a lot about the part! Connecting elements, contours, shapes and enclosures can also provide dimensions and reference for your new part; you will find out in [Decomposition].

Furthermore, you will need (access to) a fairly decent computer. As you will be working with CAD and 3D scanning software, your computer needs to be able to run these kind of beefy programs. However, all CAD programs that I am aware of only run on one processor core, and the processing of a 3D scan will be done ‘in the cloud’, on a special server for that, so don’t be scared of super steep computer requirements. Make sure that you have a x64 Windows version though, and Autodesk recommends at least 4GB of RAM and a dedicated graphics card with at least 512MB GDDR memory.

Lastly, you obviously need access to a 3D printer. The guide and tools, as well as my studies are focused on desktop, FDM-based 3D printers, as they are by far the most common and accessible type of printers. This type of printers are for sale for consumers, ranging from €99,- up to tens of thousands, but generally cost around €3000,-. Assuming you will not make such an investment for a single case - if not already owning a printer - I’ve included a couple of useful platforms for finding a printer near you. If you happen to know someone, or a shop/library/school/business/workspace that owns a 3D printer, it is definitely worth informing if you can get a model printed! Often, these people are very interested and willing to help you with your case as well!

Additional tools

The following tools are needed in the process as well:

A proper working area and adequate safety clothing.
An Autodesk account and licensed copies of Autodesk Fusion 360 and Autodesk ReMake. Both are free for Hobbyists, Students and Start-up companies! Download here: Fusion 360 Remake and upgrade to a 1-year free license
A digital camera or smartphone, preferably one that you can set manually (for instance, a DSLR). Any camera works, as long as it has a decent image resolution (10MP+)
A caliper, preferably a digital one, as you will be measuring sub-millimeter dimensions
Other measuring tools, such as a protractor, ruler etcetera.

Step 5: Start!

That it! Feel free to use the process poster, guides and tools throughout the process and learn from my experience (and mistakes) how to make a substitute part for your case. I am very interested in your experience and any improvements, tips or comments on this series of guides! It will help me improving the guides, as well as my research work!

Thanks a lot in advance,

Good luck!

1 Decomposition guide