Letters from the Lab #008

About the Author

Tom posing in front of his Ford Fiesta.


Having initially studied Physics, Tom Llewellyn-Jones made the move to Engineering to carry out his PhD at the Bristol Composite Institute, where he met co-founders Simon (CEO) and Michael (CTO), and also first started working in 3D printing.

As Head of R&D, Tom’s role now largely revolves around managing Actuation Lab’s growing engineering team to ensure we hit our ambitious targets.


How 3D printing made hardware development 10 times cheaper


Given how much we use 3D printing at Actuation Lab, I thought I would write about how the technology has revolutionised R&D processes over recent years, and to develop our new products.

Before the arrival of 3D printing, developing a novel concept would have been prohibitively expensive for a lot of companies. It would have been difficult to test a proof-of-concept, let alone manufacture a trial unit or prototype, and as such the project would have been considered too risky or expensive.

Nowadays, 3D printing allows even small companies to rapidly design, build, test and iteratively redesign new ideas.


A successful batch of freshly 3D printed Callimorphs, still on the print bed.

A successful batch of freshly 3D printed Callimorphs


What is 3D printing?


3D printing does not really relate to a single concept, but has come to be a wide umbrella term for lots of different technologies. Generally, 3D printing describes any method of “Additive Layer Manufacturing”, i.e. a manufacturing process where material is added incrementally, to build a part in layers. This is opposed to more well-known “subtractive” manufacturing methods, where you start with a block of material and remove (subtract) bits until you end up with the desired shape, such as milling or turning.

While there are many advantages to the additive approach, such as lower waste and potential for improved energy efficiency, the key benefits are the achievable complexity and the low iteration time. Fine details can be hard to remove from a big block of material, but when you are building from the ground up, you can put material pretty much wherever you want. Small design changes to complex components can be quickly implemented, manufactured and tested.

3D printing technologies exist to manufacture plastics, composites, metals, and even some more unusual (and arguably less useful) materials like hydrogels and chocolate. Different technologies are required to achieve this:

  • Fused Deposition Modelling (FDM) printing involves extruding plastic through a fine heated nozzle, which moves to deposit the molten plastic where needed.
  • Stereolithography (SLA) printing uses a bath of liquid resin, which cures and solidifies as light is projected onto it.
  • Selective Laser Sintering (SLS) printing uses a bed of fine plastic powder, which is, as the name suggests, selectively sintered (fused) together by a laser.


Graphic depiction of the layer-by-layer mechanism of FDM printing

FDM printing, building full components layer by layer with molten thermoplastic
[Image adapted from work by mpaulo@kiefe.com, CC BY-SA 4.0, via Wikimedia Commons]

In all these cases, the parts being printed are built up layer by layer, hence the term “Additive Layer Manufacturing”. Each technology has its associated pros and cons. At Actuation Lab, we predominantly rely on FDM printing, due to its ease of use, low cost, speed and ability to create structural parts from a variety of materials, with the possibility of printing with any thermoplastic.


A short history of 3D printing


Initially, many of the different forms of 3D printing were commercially developed in the 80s and 90s, at which time they were patented. Given that patents are granted for 20 years, many of these expired in the late 2000s and early 2010s, driving a notable step change in widespread 3D printing.

In 2009, a patent owned by Stratasys expired, which opened the door for cheap and open source FDM printers to be produced and sold by anyone. This triggered the creation of companies such as Ultimaker and Makerbot, whose products quickly became ubiquitous throughout university engineering departments.

This democratisation of the technology has meant that more people have direct exposure to working with it. Thanks to its inclusion in university workshops, many new graduate engineers now have good experience working with 3D printers and can drive increased use within the organisations they end up working in.


A bumpy start


At the risk of sounding like a grumpy old cynic, when it comes to 3D printing, things were harder ‘back in my day’. The technology has changed a lot, and quickly, since I first started using it 10 years ago.


An Ultimaker Original FDM printer, made mostly of plywood, with arrows pointing to various elements: Extrusion head mounted to x-y carriage, Thermoplastic filament feed, PTFE Bowden tube, Printed part, Heated bed, Z-axis lead screw.

The early days (some would say the golden age) of 3D printing


My first hands-on experience with 3D printing was in 2012, whilst studying at the University of Bristol, with an Ultimaker Original FDM printer. This came as a flat-pack kit, and everything felt cobbled together from existing, off-the-shelf components, aside from a laser cut plywood frame. The controller was an Arduino fitted with a massive expansion board. The print bed (the surface on which the part is built) was a pane of glass, most easily replaced with mirror tiles from IKEA when damaged.

Bed levelling (the process by which the height of the print bed is calibrated to ensure that it remains the correct distance from the print nozzle across its entire area) involved adjusting four spring-loaded screws, one in each corner of the bed, with a piece of paper under the nozzle to feel for just the right amount of friction. And if your bed wasn’t level… your print would turn into a big stringy mess!


A 3D print gone wrong, resulting in a stringy mess of white filament, which is reminiscent of noodles!

A perfect example of “stringy mess”


Another example of 3D printing gone wrong: a white filament blob is still attached to the extruder.

Another common print failure type, where material sticks preferentially to the nozzle block rather than the printed part, and “snowballs”


Looking back at these pictures of the first printer I used brought flashbacks of many little bugs and frustrations. Filament melting and getting stuck in plastic inserts; leaving huge scratches in the glass bed when the manual bed levelling didn’t go to plan; having to reload the entire firmware just to change one setting, with the ever-present risk that the control board would become an expensive paperweight if the cable moved; the near impossibility of printing flexible materials properly.


Diagram presenting the 2 types of variables that can affect various aspects of the quality of 3D printed parts, showing the very complex interdependencies of the variables. The variables in the Physical properties column are: Nozzle diameter, Nozzle temperature and Bed temperature. The variables in the Print variables column are: Travel speed, Fill density, Print head speed, Layer height, Shell thickness and Flow rate. The variables in the Part quality column are: Part density, Speed of manufacture, Surface finish, Layer adhesion, Bed adhesion and Dimensional accuracy. Arrows interlink the elements from the Physical properties column to elements of the Print variables and Part quality columns. Arrows also interlink the elements of the Print variables column to elements of the Part quality column.

Non-exhaustive flow chart to show how variables affect each other, i.e. how easily it can all go wrong


This was time-consuming, inconsistent, and frankly a bit of a dark art. This sort of setup is still common on a number of low-cost, hobbyist-level printers, but isn’t suitable in a work setting where downtime and variability can be costly.


A tipping point in the history of 3D printing


Frustrations certainly still exist, and I probably have to spend a little time every month mending a wobbly printer, but the success rate has improved drastically. Things like automated bed levelling, purpose-built control boards and all-metal heater elements have completely changed the way we work with our printers, such that even fairly affordable systems are now able to run without intervention for weeks or even months at a time.

Alongside these hardware improvements, software development is continually lowering the skill barrier to entry and increasing success rates. To test our pneumatic actuator prototype, we need to 3D print demonstrators, which require airtight, thin-walled printed parts. As recently as 2018, this required custom code to prevent unwanted print paths and ensure no leaks were introduced. Now, we can simply turn on a feature with a single click in several freely available software packages, such as Cura and PrusaSlicer.


An improvement visible across industries


So what does the availability of this new, versatile and increasingly reliable manufacturing method mean for the world of R&D? This brings us back to the question of “why hasn’t anyone done this before?”

A good example lies in the automotive industry. Today’s engineers and designers are not somehow intrinsically more capable than their predecessors, with greater imagination to make cars with smooth-flowing, curvy geometry. Engineers always aim to achieve as much as possible within the limitations of the tools they have access to. In the past, the design process would have been achieved through hand drawings, and with wood or clay mouldings, and the downstream fabrication methods were not yet capable of forming finely detailed, complex structures. You don’t have to go very far back in time to see that mainstream cars were square boxes.

It was only in the 1980s that designers had access to computational design tools, and only in the late 90s/early 2000s did these tools reach a level where they could easily surpass the detail achievable with drawings. For instance, compare the two Ford Fiestas below.


Ford Fiesta from the early 1980s in a shade of red

Ford Fiesta from the early 1980s
[image by InspiredImages from Pixabay]

21st century Ford Fiesta in a shade of red

21st century Ford Fiesta
[image by