/ Technology

3D printers are great, but can they really print spare parts?

3D printers present users with lots of possibilities, making them a technology darling in the past few years. Are they answer to fixing your broken appliances? 3D printing expert Dr. Mike Vasquez explores…

As an expert in the field of 3D printing, I have seen the users of the technology evolve from just skilled engineers to include the average Joe and Jane tinkering with a Makerbot in their garage.

Why so much hype and excitement about 3D printing? There are several reasons, but the main attraction is that the technology enables users to create highly complex shapes, something that wasn’t possible before and offers exciting opportunities for design and innovation.

Commercial and consumer opportunities

For companies, this technology continues to be attractive for research and development, production and to eliminate the need to create molds or tooling. As a result, it can save companies thousands of pounds and weeks of lead-time during the product design phase. This makes it highly attractive for prototyping and other small-scale manufacturing needs.

But the technology is also expanding to become of interest to the mainstream population. The expiration of key patents for material extrusion and some stereolithography technologies has resulted in a wave of machines that are much lower cost than their industrial counterparts. This has enabled people to bring the tech into their homes. As access to the technology expands, some hypothesise that people will soon be able to use their consumer-grade printers to fix broken appliances or parts in their home…

3D printing spare parts

Let’s dig a bit deeper to try and better understand where the technology is today and whether you’ll be able to use them to fix broken parts.

For consumer 3D printers, there remain a lot of inconsistencies that some of their more expensive cousins do not present. As I talk to clients in my consulting business, there are four key considerations I suggest to think about when purchasing these table-top machines.

For the purposes of this discussion, let’s say that you want to print a replacement part for your refrigerator:

Design: In order to 3D print the part for your fridge, you’ll need a digital design. There are two ways to get that – either contact the original manufacturer to get a 3D file (which they may or may not provide) or recreate the part yourself, which requires using 3D design software to create the part from scratch.

Materials: Once you create or obtain the 3D digital design file, the next hurdle is selecting the appropriate material. Different materials will offer different properties (in the case of your refrigerator part, for instance, ability to withstand cooler temperatures may be a requirement), so it’s important to select and use the right one. Many home printers only allow for a limited number of materials to be used, which can be a challenging limitation.

Machine: It is true that 3D printers are evolving, but for low-cost printers especially there can be issues with setup, operation and repeatability. The quality can vary widely and the mechanical properties often do not match those achieved in traditional manufacturing or using a high-end 3D Printing machine.

Finish: The layer upon layer manufacturing process used by 3D printing results in small voids within and between layers. These voids contribute to lower mechanical properties but also less smooth surface appearance, and may require you do some ‘post-production’ work to clean up your part before using it.

Clearly, there are some limitations with the current technology, but these are opportunities for innovative tech companies to disrupt the status quo in the industry. Given the focus and interest in developing this technology, the industry is likely to advance significantly in the next few years. For those contemplating how to integrate the technology today, understanding the constraints will ensure you make smart decisions when it comes to 3D printing.

Which? Conversation provides guest spots to external contributors. This is from Dr. Mike Vasquez, founder of 3D Printing Reports. All opinions expressed here are Mike’s own, not necessarily those of Which?.


I would suspect that for most consumers the lack of a digital design file will be a fatal stumbling block.
I cannot see manufacturers releasing design files , it is not in their financial interests and they will of course cite H&S as a final resort.

It is the small often critcal plastic parts that hold things together, open,shut, activate switches etc which I ,and I suspect many others, would like to be able to print to enabl eth continued use of older consumer products.
Even small parts for products 2/3 years old are not available.
However being positive I do believe there is great potential in 3D printers especially with prices coming down.

Two limitations – lack of suitable materials in many cases and 3D design ability required. Probably fun to create your own small items if you have the 3D software and ability, but personally I would see traditional skills for making stuff being with us for a long time.
It may be manufacturers or 3rd party bureaux could hold design files for spare parts that could be made on demand – we need to satisfy a need for those small bits that fail and cause a whole device or appliance to stop working. Printers for example.

All I can say is urghhh..

As a non-practising engineer who studied manufacturing engineering and materials science at uni l was appalled at all the junk tech hyperbole last year about ‘3d printing’ and how it would mean you could print replacement parts at home, revolutionise high streets and even print more printers… except.. you can’t for 99% of ‘things’.

Consider that that nearly all consumer printers act by melting plastic. This is fine for objects that where made with the same/similar plastics, but you can’t replace an item with something made out of these plastics if the plastic isn’t suitable either mechanically or chemically. You would also have to clean up and further treat the item to make it suitable – have you seen the finish on these things?.

But what of metal items? Yes you can print these, it’s been going on for years. There are fighter plans, F1 cars with printed components for instance. However, its very specialist (see sintering or metal deposition) and these machines are industrial due to their size and cost. You’re also talking about processes that are a tad unsuitable for the home (industrial laser’s in the kitchen anyone). Then there is all the clean up and further machining once the item has been created.

Of course forget anything electrical.. You could print the case and buttons, but what about the screws, wires, pcb, chips and other electronic components? What about the cracked screen on you’re iphone?

Where current tech does show promise is where people need small things that are a bit crude and you only need 1 or a few of – Industrial designers, architects, inventors, prop makers, jewellery designers and schools (that would be fun for kids). And indeed 3d printing is rife in these areas.

Or perhaps in places where spares are hard to come by and the spares you need are for simple things (not your Mile dishwasher) and people aren’t concerned about the finish. There was talk of printing cutlery and crockery, yet this was tried in the ’50’/60’s and thankfully stayed there. Yet there are possibly places in less developed areas where this could all be a great boon.

There is a future for this. You could in theory make a ‘mini factory’ in a big-ish box. Combine 3d plastic printing with metal sintering/ deposition, cnc machining, pcb fabrication and some robotics and there is no reason why this big box couldn’t make a lot of things. Those things would be designed and built with the limitations of the factory, so no Jonny Ive products, and it would probably be very expensive. But if your stuck a long way away, a long, long, long way away and can’t order from Amazon or sparesOnline (say Mars) then it could be very handy.

Anyway I need to order a new knob for my (Mile) dishwasher. What I wont be doing is splashing out £1k on a printer to make it. Rather £10 (still steep) at one of those online spares places instead.


I doubt that affordable 3D printers will have educational and creative uses but I doubt that they will solve the need for spare parts. I hope I am wrong.

I see more chance of small companies providing a service using commercial grade machines capable of handling different plastics and with extraction facilities to remove toxic fumes created by plasticisers etc. A 3D printer incorporating a 3D scanner would be useful to recreate broken plastic components. Broken items may not be strong enough for use if the pieces are stuck together, but would be adequate as a template for copying.

The obvious benefit of a 3D scanner/printer is that it would remove the need to obtain design information from manufacturers. If our Miele dishwasher knob is broken, it might be possible to produce a better quality replacement.

I thought this was interesting – some one 3D printed new knobs for his grandma’s stove: http://imgur.com/a/RCihv

Fascinating stuff. It would be interesting to know whether this was done using a home 3D printer or a professional one, what plastic was used, and whether the new knobs are strong enough to be durable.

A combination 3D scanner/printer would have avoided all the design work, but perhaps that’s part of the fun.

It looks like they sent it away to be printed professionally. I think the consumer ones use a plastic that melts at low temperatures, so might not be suitable for a stove!

Hey all

Laser scanning works by shining said laser over surface and reading the reflection back in a series of points. With a bit of maths you can work out in space where the point was. Sounds easy enough. But when you have shiny / reflective surfaces (like most plastics) the laser light gets scattered. At the very least this decreases the accuracy of the reading, but can also leave holes in the data or no data at all. When scanning such items you need to dull them down for it to work (you can get a spray to do this). If the object has any transparent or translucent surfaces your going to be in trouble too.

Another issue is cavities, holes, folds or any surface that the laser can’t see directly (think the internal sides of a tube or the hole in the knob). If the laser scanner can’t see the surface directly it can’t measure it.

When you have scanned an item what you actually have is a cloud of points in 3d space. It’s then up to software to work out how all those points join together. With simple objects the software can do a good job figuring out the surface. But where you have lots of detail then it can run into problems which requires a user to fix. The resulting surface wont be smooth either. The surface will be made of lots of triangles, each corner of the triangle being one of the points in the cloud. Depending on the size of the object and the tolerance of the scanner, even if the the surface of the original object is perfectly smooth and in the same plane, the points created wont all be in the same plane and you can end up with a surface that is rough and not exactly matching the original.

When we (I work in film VFX) get scan data it’s normally been cleaned up a fair bit to start with (filling in holes, removing erroneous data etc) which we then use as a handy guide (often as we don’t have the original object anyway) to modelling the object in 3d. To use scan data for printing out an object, unless your happy with an approximate copy (and the scan data is in good shape) you will need to do the same. To get the accuracy you will need to measure the real object as well (which the guy from the link above did). If the object includes cavity’s, holes, hidden volumes etc you will need to model them anyway.

Obviously, with good software you could help solve some of the issues with a little human intervention. But to reproduce items that need accuracy or complex shapes then it would be a fair amount of work, totally possible though 🙂