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Prototyping Essentials

Your (hopefully) most spartan guide to knowing 3D printing, CNC machining and laser printing.

Before the modern digitalisation of the world, engineers relied on making sketches and hand-drawn blueprints, making physical mockups of their designs to visualise them before their final production.

This process from creating the idea, then prototyping to finalising the design is still essential to designing products, services, software — congregating to offer the best user experience.

We’ll be focusing on the middle child in this three-step process, however, it should be mentioned that prototyping can be split into 4 categories!

This article by Mette Jest Tjellesen covers this in great detail if you are interested in knowing the differences. For today, we’ll not need to know the differences, but they are most applicable to the “product prototypes” category — to quote Tjellesen:

Product prototypes represent nearly finished products and are used 1) to test the ‘depth’ in a digital solution in matters of technical integration to other systems and/or 2) as a beta version of the product with a focus on user feedback and optimization — before going live.

Prototyping

Following our brief introduction, let’s have our brains do some work. I want you to consider the ways we can construct a prototype.

Don’t worry about the aforementioned categories, but try to come up with five materials, techniques, or software that we might need for building prototypes.

For context, you could use the inset illustration of a metal sculpture from the title photo for reference, though anything will do most certainly.

Have your list? Great!

Here’s mine: Lego, Cardboard + Masking Tape & Craft knife, Clay sculpting, Figma prototyping software, Turning (wood).

The few that I have mentioned here may be new and unusual, but it’s to create some distinction that prototyping can be incredibly simple like using Lego. Though, when precision, accuracy and functionality are parameters we have to consider, that’s when complex techniques and technologies should and need to be involved.

Now that we’ve established a rough idea of prototyping, let’s look at Prototyping with 3D.

Namely 3D printing, CNC machining, Laser/Plasma/Waterjet/EDM cutting, Thermoforming and also Turning.

They are all incredibly precise, versatile with a common denominator of producing well-finished products. These technologies represent a surface view of an underlying giant interconnecting web of technologies so to help our understanding of them, I’ll be linking relevant resources throughout this article.

No1. 3D printing

An additive process (layering material to form the shape wanted) in fabricating 3D models. It usually involves the ability to produce highly accurate and detailed prototypes at relatively economical speeds so it’s suitable for almost any type of prototyping!

Product prototyping stages where higher detail mockups are required is where 3D printing truly shines however with its sweeping range of customisation opportunities.

A. Customisation!

FDM, SLA, SLS (not the NASA one!) are a select few in a sea of technologies present in the 3D printing industry. Frustratingly, having about 10 different ways to 3D print something means there are many parameters to consider when choosing a method. A few common ones would include the product size, printing material, scale of production, targetted functionality and more.

For instance, if we were to print something bouncy or elastic and was able to morph under stress, it would be sensible to use TPE or TPU, which are compressible materials with the ability to sustain a considerable amount of force.

Though, what if we wanted to produce a strong stiff component for mechanical purposes?

Metal is usually used for this type of purpose due to its mechanical strength, chemical resistance and longevity, However, customising and obtaining such parts is either impossible due to high costs and unavailability, or requires significant time due to slow speeds. In this context, using PEEK, PEKK, or ULTEM would suffice because of their compatibility with normal 3D printers while offering similar performance.

Going back to the parameters we have to take in mind, it’s essential to know that they are not mutually exclusive from one another.

A particular example here would be how different materials will have different melting points, printer settings, structural limits and more. Considerations like these need to be planned out from the start and are essential to achieve certain effects.

B. Software

A wise man once said:

3D printed models are essentially the products of moving a fancy, super-hot nozzle — and maybe the printing bed — on a 3-axis cartesian plane via stupidly precise motors.

I agree with this — ahem, “wise man”.

To extend upon his point, something called G-code is used to move the nozzle and/or printing bed. G-code can be generated by uploading our 3D model into slicing software to specify the effect of the product we want to achieve. Ultimaker Cura for example allows for defining constraints, support structures, model density, nozzle size, layer thickness amongst the plethora of settings.

Switching the camera on the opposite side, we have the modelling process. For this, a mix of 3D modelling or CAD software is used which allows us to create, modify and prepare our 3D models for printing. SolidWorks, TinkerCAD, blender, Autodesk AutoCAD are a few to name — or you can simply download your models from the internet.

C. Here’s your toolkit to get started:

3D printer, slicing software, 3D modelling software, plastic filament, some tools, a good pair of hands, some money and maybe a nice holiday.

D. Resources for further reading:

Types of 3D printers || Types of printing material || List of modelling and slicing software || 3D printing tips

No2. 3D CNC Machining

The split opposite of printing, CNC machining is a subtractive process that involves the removal of material. CNC involves mainly turning or milling and is used with aluminium, wood, foam or even acrylic. Essentially, we are moving a drill/milling bit (instead of a nozzle) to shape a block of material into the form intended.

CNC machining can be said to be rarely used for prototyping due to its exclusivity, operational difficulty, and high expenditure. However, with freelancing and the general introduction of company services, the accessibility to this process is now much improved. The customer only has to upload the specifications and 3D model to the operator to machine them at the factory, before they send the finished product back.

A. Versatility and Flexibility

Now that we know the simplified operations of CNC machining, it should be known that CNC machining can operate on 3-axis or 5-axis systems. 5-axis systems involve the X, Y, Z-axis from a 3-axis system, with an additional A (rotation around X-axis) and B (rotation around Y-axis) axis.

This allows the whole drilling bit (or in some cases the subject itself) to pivot about its centre to achieve certain angles. This constitutes certain cutouts like a hole at an angle to be possible.

What we want to focus on also is the technical advantage of being able to machine a wide variety of materials. Being thorough with machining metal makes machining virtually anything else relatively easy. As long as the material is within the range of wood, metal or some solid plastics like acrylic, machining is similar for all three types and this opens up many possibilities. The process isn’t as straightforward as it sounds but comparatively, for 3D printing, printing metal is a whole different process than printing plastic.

B. Tools

CNC machining is highly dependent on the “bit” used when milling and turning.

“Bit” /bɪt/ (also known as milling bit/router bit/carving bit/end mill)

Definition: the metal steel (sometimes containing diamond) head that removes material from the subject by spinning it at high speeds. There is a multitude of different bit shapes for optimising certain cutting procedures.

Rounded edges, sharp edges, divots, holes, all will need different milling bits. So if you were to machine a hemisphere, you would need to use a ball nose milling bit (basically the bit is rounded at the end).

There’s a very wide range of techniques to obtain the ultimate balance of speed and finish (surface look). How fast the bit is spinning (RPM) and the type of milling bit used are the two major parameters to control the balance.

C. Software

Programming is the most intricate part of CNC machining. There’s almost no room for error and it’s in general very unforgiving due to the high speeds attained from the drill bit. A lockup on the bit when machining would send the workpiece flying; overheating from friction can cause damage to the workpiece and bit itself; an inappropriate jig used when machining can cause inaccuracies when machining. It’s why programming can be extremely lengthy due to safety and quality checks.

The software side of CNC machining can get very complicated so here’s a rough summary.

  1. CAD software — for modelling the design in a 2D/2.5D/3D virtual environment and preparing it for machining. Examples: SolidWorks CAD, AutoCAD, Fusion360, Easel CNC Software
  2. CAM software — stands for Computer-Aided Manufacturing. Converts the design, outputting G-code (like 3D printing’s slicing software). Some software like Fusion360 have CAM software integrated into them, but there are those which have it separate. Namely SolidWorks CAM, OpenBuilds CAM allow us to establish specifications of the type, angle, speed of the milling bit. Sometimes multiple bits are required so those are specified here too.
  3. Control software — converts the computer into a CNC machine controller to manage the motion of motors etc. Most CNC machines also come with controller firmware which the control software interacts with. Examples: Mach 4, LinuxCNC, PlanetCNC, OpenBuilds Control
  4. Simulation software — reads G-code generated and predicts errors that may arise while machining. This helps us prevent the issues mentioned! Examples: NC Viewer, G-Wizard Editor, CNC Simulator Pro

At this point, you can quite clearly see the differences between CNC machining and 3D printing, they are similar in their use cases and some of the software used but the learning curve is much greater for CNC machining. I, unfortunately, won’t be touching on their differences much in this article, so you can check out BigRep’s article on the differences between 3D printing and CNC machining.

D. In a nutshell:

CNC machining is hard. That’s all I’m going to say.

E. Resources for further reading (and watching):

History of CNC machining — video | Foam CNC machining example — video | 5-axis CNC machining demo — video | Types of CNC machining bits ||Best CNC software

No3. Laser cutting

Laser cutting involves the use of a high power laser incident on the cut material. The area it is incident on melts, burns, vaporises or is blown away by a gas jet. Other similar technological advances include plasma cutting, electrical discharge machining (EDM).

A. Suitability

The general theme is laser cutting is suitable for wood and acrylic, plasma for sheet metal, EDM for cutting out thicker metal blocks. From this, the cutting ability of each of the materials can also be seen, laser cutting being the weakest and EDM being the strongest though also most expensive to operate.

*Laser cutters can also be powerful enough to cut metal (as seen later)

The laser cutting process is relatively simple:

  1. Design the actual model in 3D modelling software.
  2. Split it out into individual parts in 2D vector manipulation software.
  3. Setup the settings on the laser cutter.
  4. Upload the vector file (eg .svg format) or for laser engraving/etching, a raster file (eg .bmp format). There are also many other specifications.

No fancy software is needed, no need to learn a variety of equipment and minimal precautions are necessary. It’s relatively quick to get started and achieve a good product.

Plasma and EDM cutting however can get very confusing and will introduce confusing physics concepts so I will not dive into this area for the sake of complexity. If you are interested, you can find the links to read more about them at the end of this section.

B. Physics (of laser cutting)

In comparison, laser cutting is the most sophisticated in the physics department. 3D printing simply uses the concept of melting and solidifying; CNC machining applies the idea of hardness and shear forces. Laser cutting introduces us to the process of generating lasers, so we are using the electromagnetic spectrum, and some tropical physics concepts (depending on the type of laser — there isn’t only one way, in fact, there are 3 main ways, we’ll dip our toes in this later).

So. How do laser cutters “cut”? I mean, scissors cut because of the concentrated shear forces applied to the piece.

Recalling our overview, the focal point of the laser is incident on melts, burns, vaporises, or is then blown away by a gas jet. That’s exactly how these laser cutting works, though this process of achieving such a powerful laser of 1 to 3 kilowatts at 0.1 to 0.3 millimetres in diameter is quite simple. It involves the use of a curved lens(es) to focus and magnify the generated laser beam into a single thin concentrated beam, which is the beam we see cut the workpiece. This beam can be seen to set small fires on the point which eats away at the material.

The types of lasers, however, include Gas Laser/CO2 Laser Cutters, Crystal Laser Cutters, and Fibre Laser Cutters mainly.

As the name says, CO2 lasers are produced through electrically-stimulated CO2, in a gas mixture of nitrogen, helium, to include a few. Crystal lasers are generated through the excitation of electrons in the crystal, which results in them rising to a higher energy state, before releasing the energy in the form of photons (light), which when concentrated gives us our laser beam. Fibre lasers on the other hand amplify certain wavelengths inside optical fibres, in a way filtering the light that is passing through.

So what’s the point of all these lasers? I mentioned before that you can cut many materials with laser cutters. It’s not always the case, as CO2 laser cutters cannot cut metal; crystal laser cutters cannot cut wood; fibre laser cutters meanwhile can only cut plastics and metals. These are due to the limitations in the beams produced.

C. Software

Moving into this last part, we can use almost any vector software, 3D CAD software, for creating the file for upload. There is no need to convert it into G-code which is handy, all that is needed is to adjust the settings of the laser cutter. This means even Adobe Illustrator is suitable!

D. In summary:

Laser cutting requires very little software and preparation to get started. So, it could be a good mini project if you have a laser printer lying around your house or office!

E. For additional reading:

Laser Cutting Basics | Preparing files for laser cutting | Laser vs Plasma cutting | Plasma cutting | EDM cutting

Conclusion

3D printing, CNC machining and laser cutting are three very different techniques in prototyping a product. They have their pros and cons. They all however have the same common theme of being learnable.

In any case, I hope you have enjoyed this journey. It probably was a lot to take in if you haven’t heard of any of these before, so consider saving this article or the LinkedIn post for future reference perhaps. For those who knew some and were able to gain more insight, I’m glad to be able to help. And finally. For those who knew absolutely everything already (or skipped the whole article!) and I wasn’t useful in any way, I appreciate that you took a glance.

With that, hopefully, this motivated some to pick up a few hands-on skills so that your future prototypes aren’t rough pieces of cardboard stuck together, or made out of Lego (though I’d argue that it’s kind of useful). If so, good luck with your efforts!

Final words

As of publishing, this article will also be marking the end of my internship at KidoCode. This journey has been a wild, new, joyous, and sometimes nervy experience, but it’s not without the accompaniment of all the people I met along the way. For this, I’d like to bid my fairest thanks to my colleagues, the utmost gratification to the friends I was able to make, and lastly my heartfelt acknowledgement to my supervisors and mentors: Danson, Carol, Srivaani, Mojgan, and Afsa.

Thank you, reader. All the best in your future endeavours.

References:

Instructables, & Crease, A. (2017, October 7). Laser Cutting Basics. Instructables. https://www.instructables.com/Laser-Cutting-Basics/

J. (2022, February 20). Best CNC Software [2022] for Hobbyists and Pros [Free and Paid]. MellowPine. https://mellowpine.com/cnc/best-cnc-software/

Laser Engraving Tips. (2022, March 29). What kind of file do you need for laser cutting? https://laserengravingtips.com/what-kind-of-file-do-you-need-for-laser-cutting

Lawrence Livermore National Laboratory. (2022). NIF’s Guide to How Lasers Work. https://lasers.llnl.gov/education/how-lasers-work

Obudho, B. (2019, August 31). What Is a Laser Cutter? — Simply Explained. All3DP. https://all3dp.com/2/what-is-a-laser-cutter-simply-explained/

Obudho, B. (2021, September 15). CNC Router Bits: The Basics — Simply Explained. All3DP. https://all3dp.com/2/guide-to-cnc-router-bits-all-you-need-to-know/

Swanton Welding Company. (2017, February 16). What is 5 Axis CNC Machining? https://blog.swantonweld.com/what-is-5-axis-cnc-machining#:%7E:text=5%2Daxis%20machining%20refers%20to,cutting%20tool%20a%20multidirectional%20approach

Credits:

Figure 1.0 — Modified inset photo by Louis Mornaud on Unsplash | Figure 2.0 — Inset photo by NEW DATA SERVICES on Unsplash | Figure 3.0 — Formlabs, Ultimaker | Figure 5.0 —HAAS | Figure 6.0 — harveyperformance.com | Figure 7.0 — Avid CNC | Figure 8.0 — Nervous System Blog | Figure 9.0 — Purdue University Bechtel Innovation Design Center | Graphics done in Figma + Photoshop CS6

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Zhe-Wei Kho

Zhe-Wei Kho

I write inspiring and informational pieces. About biennially, if you are lucky.

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