Introduction

Producing parts that reference real-world objects can be an essential element of technical workflows, from precision engineering to art. 3D scanning is a key piece of this equation, and alongside 3D printing it creates a powerful digital workflow that can simplify and sophisticate processes in a range of industries. This white paper provides a detailed look into how to start using 3D scanning to improve part design and production. It will look at different scanning use cases across various industries, and showcase real-life case studies, including:

• Reverse engineering to create replacement parts, products with custom ergonomics, and more.

• Replication and restoration of parts, especially in art and jewelry.

• Consumer audio for creating custom earpieces.

• Dental and medical applications, and how 3D scanning is enabling patient-specific workflows.

• Metrology to validate and measure the accuracy of manufactured objects. By the end of this report, you should have an understanding of how 3D scanning paired with 3D printing can be effectively applied to multiple applications across industries, from reverse engineering, restoration, digital dentistry, replication, and more.

How Does 3D Scanning Complement 3D Printing?

A 3D scanner expands the capabilities of a 3D printer, allowing you to replicate the shape of almost any object. The use-cases for this combination are expansive, from replacing expensive machine parts to re-creating models and props in CAD to make or modify replicas. Together, the two technologies create a powerful, digital workflow that can upend a range of industries. The output from a 3D scanner is a mesh of triangles representing the surface of an object at a real-world scale. In some cases, the scan can be used directly to replicate objects without any CAD work. Due to the power of modern SLA printers, almost any object correctly designed in CAD or captured from a scanner, from customized ergonomics to parts that mimic a physical imprint of a part of the human body, can be turned into a physical 3D object.

3D Scanning & 3D Printing Applications Examples

Multiple powerful workflows are enabled by combining a 3D printer and a 3D scanner.In this section you will find examples of 3D scanning and 3D printing used in conjunction for:

• Reverse engineering
• Replication
• Consumer audio
• Dental
• Metrology
• Emerging smartphone business

REVERSE ENGINEERING AND 3D PRINTING

Reverse engineering is a method of reconstructing a design from an existing object, so that the design can be modified or adapted. In practice, this means measuring an object (usually with a 3D scanner) and converting the 3D scan into a solid format that is compatible with CAD modelling tools. For 3D printing, reverse engineering is a method to increase confidence in your design and can be an intermediate step when creating custom organic shapes. Instead of replacing an entire machine, scan broken parts and re-print them for a few dollars per part. Generally this workflow looks like the following:

1. 3D scan: Use a high-accuracy 3D scanner to scan your object. Try to capture as complete a model as possible.

2. Convert to solid: Convert the 3D scan into a solid format that is compatible with CAD modelling tools. Repair small gaps or redraw and resurface mesh if needed. CAD software such as MeshMixer is a viable option. Some mid-to-high range scanners come with first-party software that allows users to clean up, align, and finalize a mesh for 3D printing. This eliminates the need to use 3rd party software; businesses should consider their CAD needs when making a purchasing decision.

3. 3D print: Import your model to PreForm, the 3D print-preparation software for Formlabs printers, and send the part to your 3D printer

4. Test and integrate: Measure and test your part. Iterate the design or integrate the replacement part into your machine. Reverse engineering is often used as the basis for new designs to be assembled with existing components. Without modelling every relational object, it can be difficult to catch all potential issues that might arise from assembly entirely in CAD. Attempting to reverse engineer parts in CAD first can result in a costly trial and error process. 3D printing allows you to quickly test and iterate on reverse-engineered designs in physical space, where it’s much easier to recognize any issues. In addition to large-scale design changes, it’s important to be aware of possible fit issues arising from measurement error. If the target object has undercuts, very thin bosses (raises above a surface), or deep pockets that are challenging to scan, you might need to use guesswork to fill in missing regions in CAD. Physically assembling a printed prototype can be a quick way to find and resolve potential spatial conflicts in your design, whether caused by new modifications or measurement errors from scanning.

The variety of materials available for SLA printing enables reverse engineering projects in diverse circumstances, allowing you to scan and print almost any object depending on your application requirements. Before investing in a 3D scanner and printer, make sure the materials you will be using match your project requirements.

To see these steps in action, view our free webinar titled: “How to Reverse Engineer an Assembly Jig with 3D Scanning and 3D Printing” below.

REVERSE ENGINEERING CASE STUDY: CUSTOM FUEL INJECTOR GRIPPERS

Headquartered in Wisconsin, STS Technical Group has been operating for nearly 40 years working with clients on staffing, technical design, and engineering challenges. Warehouse companies consider many factors when designing grippers for pick and place operations. The materials used in the picked component and the gripper, grip strength, geometry of the picked component, radial jaws versus linear jaw motion, surrounding clearances, and the required pick and place location tolerances. STS Technical Group’s Director of Engineering Services Benjamin Heard used a Creaform laser 3D scanner and VX Elements modelling software to get a virtual 3D scan of the fuel injector to assist with the design of the grippers. The scan resulted in an image with intricate details, and scanning eliminated the time it would have taken to measure every gap, cylinder, and opening on the fuel injector. The scanned image could then be imported into 3D CAD software to generate an extremely detailed design using a mold feature in the software.

The process of designing and 3D printing the irregular grippers was a complete success and they operate as expected. The capabilities of the 3D printed grippers are far superior to the previous grippers, including a greater surface area to grasp the fuel injector, leading to less damage and scratches on the fuel injector.

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REVERSE ENGINEERING CASE STUDY: IMPROVED INTAKE MANIFOLD

Andrea Pirazzini, the founder of Help3D, used Formlabs 3D printers to create an intake manifold with improved thermal performance for a pit bike that he rode at the 12 Pollici Italian Cup championship.

After consulting the specifications in detail, Pirazzini thought that 3D printing an intake manifold, a part that’s traditionally machined from aluminum, would be an interesting project. In the past, he had tried using FDM technology, but the result was not what he hoped for, as air leakage distorted the carburetor and the engine’s output.

To develop the project, Pirazzini used 3D scanning and Autodesk Fusion 360 software to reverse engineer the design. The scan of the four-stroke engine (two-valve) engine with its frame and carburetor helped him to correctly size the manifold and then to position it so that the carburetor would not crash into the frame or the exhaust system. Pirazzini also designed intake trumpets and intake ducts. With the use of CAD, it was possible to align the diameter of the head inlet with the carburetor, avoiding steps and any pressure drop or turbulence.

The new manifold design was printed with a Formlabs printer using the Rigid 10K Resin at a 100 microns layer height, creating a smooth surface without visible layer lines. As for the finish, Pirazzini used classic water-based sandpaper to smooth the surface. Unlike an FDM manifold, which has to be treated externally and internally to be watertight, SLA printing creates solid and waterproof parts. The reverse-engineered and 3D printed manifold was a big success: the cooling fins recorded a 40-50 degrees celsius lower temperature compared to a classic aluminum manifold.

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REVERSE ENGINEERING: CUSTOM ERGONOMICS

When a product needs to be held or touched by the human body for long periods of time, the importance of ergonomic fit increases. A fit that’s acceptable for a few minutes of use can become uncomfortable after many hours, and improper ergonomics may even lead to repetitive strain injuries.

When it comes to ergonomics and customized products, 3D printers and scanners are complementary tools. 3D printers can produce individualized components and products to order, like orthotics, hand-held grips, and eyewear, without expensive manual labor.

Reverse engineering organic shapes is surprisingly simpler than reverse engineering mechanical parts with tight tolerances, given the right tools. The “Auto Surface” function of Geomagic for Solidworks will generate a smooth CAD surface from a scan (STL) with organic surfaces. Automatic surfacing will eliminate noisy or rough surfaces—a helpful feature when converting an impression into a product.

Once you have a surface that you can edit with solid CAD tools, you can easily subtract or add
features that allow the part to interface with other generic components, like bolt hole patterns,
mounting plates, and other fittings.

Scanners

3D SCANNING TECHNOLOGIES

There are multiple scanning technologies currently on the market, all offering their own advantages and weaknesses.

Laser triangulation uses light projected onto the object to take up to millions of measurements (dots) per second. The light reflected from the dots back into the scanner’s sensor to help it capture the geometry of the object. These types of scanners are often the most accurate, and are great for highly detailed parts that have clear surfaces.

Laser triangulation scanners do have limitations. For example, this technology is not used in most portable scanners because the laser dots need to project from a stable source, and the source has to be kept a close distance from the scanned object. These technologies typically require reflective markers to be applied onto the object to be used; markers that need to be removed after use, which could be an obstacle depending on the object being scanned.

Finally, the laser dots can be harmful to human eyes, so it is important to use extra safety precautions when scanning body parts with a laser triangulation system, or to check with your scanner manufacturer to make sure the device is eye-safe.

White light scanners integrate several images (or patterns) taken at the same time from a single observation point. A pattern of light is projected and laid over the component being scanned, and then all of the images are integrated into a single 3D snapshot. White light scanners are far more common in medical applications, since it is safe to use on both humans and animals and excels when an object is not perfectly still.

Traditional white light scanners have been slower to scan than laser triangulation scanners.

Photogrammetry means the act of deriving precise measurements from photographs. It involves taking a set of overlapping photos of an object, building, person, or environment, and converting them into a 3D model using a number of computer algorithms. This is the most commonly used method when creating a 3D scan with a smartphone, since modern phone cameras are capable of capturing and combining large numbers of photos.

Photogrammetry should be considered the least expensive and least accurate method for creating prints, and is not suitable for serious business applications.

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ACCURACY

Scan accuracy varies considerably between scanner technologies, and higher accuracy comes at a higher cost. The required tolerances of your final part can be a helpful guide for determining your accuracy requirements for a 3D scanner.

'There are two main categories of scanners: white light scanners and laser light scanners. Both white light and laser scanners use projected light and an offset camera to triangulate points on a scanned object. A laser scanner projects laser lines on the object, while structured light projects a focused grid from a digital projector. White light can achieve higher accuracy than laser scanning due to the noise caused by laser speckle patterns. Both of these technologies can be found in handheld and desktop forms.

With accuracy in the range of 0.1 mm or better, laser and white light scanners are a good fit alongside high-resolution 3D printers. Formlabs stereolithography (SLA) 3D printers (such as the Form 3+) produce parts at a similar accuracy, and with a similar printable area, to the scan volume of many desktop laser scanners.

Besides the accuracy between measured points and their actual location, scanners also vary in terms of resolution, which is the distance between captured points at a given scan distance. This means that details on the scanned object that are smaller than the scanner’s resolution won’t be captured. For example, a highly accurate scanner with a lower resolution might detect the general shape of jewelry on a statue, but not clearly show individual details on a ring or necklace. Depending on your project requirements, this may or may not be a dealbreaker.

An easy way to remember these metrics is: accuracy is the measurement error between the part and digital value. Resolution refers to the density of measurements.

In general, white light scanning provides the best resolution and accuracy when compared to laser scanning. For some artistic use-cases for 3D scanning you may need a lot of detail, while overall accuracy is less important—especially if you don’t require your part to fit precisely with other parts in an assembly. In these cases photogrammetry is an excellent low-cost option to explore.

Accuracy can mean slightly different things depending on the manufacturer and scanning technology. For example, the accuracy of handheld scanners depends on the distance to the subject and the quality of scan reconstruction, while desktop scanners have consistent accuracy within the constrained scan volume. If you are considering buying a 3D scanner for precise measurement, make sure to compare like to like.

ACCURACY: 3D PRINTERS

Formlabs SLA 3D printers produce parts at a similar accuracy, and with a similar printable area, to the scan volume of many desktop laser scanners. The accuracy of any 3D printing will vary depending on which materials you use to print, and the mechanical properties of those materials, which can also affect how likely a print is to warp or be distorted in any way.

If you’re unsure about the accuracy of a specific printer, then the best way to evaluate one is to inspect real parts by requesting a free print or sample part created on the machine.

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VOLUME AND COVERAGE

The area that a 3D scanner can capture varies significantly between scanners. Find a scanner that fits your size and resolution requirements without too much overhead, as cost typically increases with scan volume.

Handheld scanners can be manually moved around the object and have fewer size constraints than desktop models. Most inexpensive handheld scanners can capture objects from the size of a basketball to an entire room. High-end handheld scanners have an even wider range, and fill the niche for all objects that require precise measurements, but cannot fit in a desktop scanner. Handheld scanners are also able to capture objects nearly instantaneously, which makes them well-suited for taking human measurements (where the subject is not perfectly still) for ergonomics and medical applications.

If the area of the model can’t be seen by the scanner, it will cause a gap in the model. You can automatically repair small missing sections with most scan software programs to create a 3D printable model. However, repaired holes are rarely accurate to the original object. For parts that demand close to perfect accuracy, auto-repair of gaps or holes will not be sufficient

Many scanners use turntables to increase what the scanner can see. The sophistication of a scanner’s turntable affects how easily and completely the object is captured: some scanners have the ability to move the object around multiple axes, imaging the object from more angles. This feature is important when reverse engineering plastic parts with deep recesses and ribs, which are impossible to capture from a single angle.

Cost concerns are straightforward; how much you are willing to spend on a scanner will reflect your business’s budget and how often the scanner is going to be used. Higher cost scanners will be able to capture small objects and create highly-detailed meshes that don’t require significant touch-ups in CAD software. Handheld scanners are also often on the higher end of the price range, due to their portable nature.

The low-cost scanning market offers a wide range of options, but you have to know what to look for.

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