Explanation – Holocreators

Lecture on reverse engineering (3D scan and CAD)

Swann Rack — Sat, 01 Aug 2020 23:16:45 +0000

The Rapid.Tech and FabCon 3.D Trade Fair in Erfurt

In 2018, the 15th international trade fair and conference “Rapid.Tech” and “FabCon 3.D” took place.
In Erfurt, 5000 visitors and exhibitors from the 3D printing scene came together. Swann Rack explained, to a professional audience, the different steps needed to reverse engineer an object.

Gears as an example project for the presentation on reverse engineering

When 3D scanning an object, you do not immediately get a 3D model that can be 3D-printed, or CNC milled. Instead, you get a point cloud that must be converted to use it inside a CAD software. This conversion process is called “reverse engineering”.

Swann Rack from Holocreators gave a presentation on Reverse Engineering at the Rapid.tech 3D Congress 2018

Step 1: The Creation of the 3D Scan

There are numerous 3D scanning techniques. One is photogrammetry, which is ideal for objects larger than 200 cm. Photogrammetry is not as accurate, but very inexpensive, especially suitable for 3D-scanning larger objects with color. A second 3D scanning technique is structured-light scanning. It >is recommended for parts sized between 5cm and 300cm and achieves very high accuracy to within +/- 0.05 mm. The third technique is CT (computed tomography) 3D scanning. If you want to 3D scan tiny objects with extremely high resolution and precision, then the 3D CT is the best choice.

Audience at Swann Rack’s presentation at the Rapid.tech 3D Congress 2018

Step 2: Reverse Engineering

After 3D-scanning the object, the 3D data needs to be converted into a CAD format—for example, the conversion of an STL file into a STEP file. Reverse engineering can be either an automatic or a manual process. It depends on the application and the quality of the 3D scan. The most complex process is reverse engineering with parametric modeling and a history tree. With this process, the 3D-scan data is manually converted into a CAD format. Manual reconstructions offer maximum functionality because every parameter of the CAD model can later be edited by the customer.

Ticket for the Rapid.Tech and FabCon 3.D Exhibition 2018

Step 3: Manufacturing—3D printing or CNC milling

The final step is manufacturing. Depending on the shape and desired properties of the object, one must choose between, for example, additive manufacturing (3D printing) or CNC milling. The reverse engineering process is complete once the client receives a perfect copy of the original object.

Conclusion

We were delighted to have been given the opportunity to speak about the topics of our daily business at the Rapid.tech 3D Congress. The feedback was very positive, and Swann Rack answered a few questions from the audience after his presentation.

May we assist you with your Reverse Engineering project?

Holocreators offers 3D scanning services, 3D scan-to-CAD conversion services (STL to STEP), 3D modeling services, and CAD design services. We are happy to support you with your projects. Please call us at +49 40 481133 or send an email info@holocreators.com

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IKEA closet repair with 3D scanning and 3D printing

Swann Rack — Sat, 01 Aug 2020 22:14:34 +0000

3D CT Scan of the Broken Part

This broken clothes rail brace is part of an old IKEA closet. Unfortunately, it did not survive the last
move unscathed. The upper part of the brace was broken, so the rail did not hold anymore.

Broken IKEA clothes rail brace

First, we 3D-scanned the part using 3D CT scanning. For this step, we visited the “Plastics Centre” in
Leipzig, where “Werth’s” brand-new industrial computed tomography 3D scanner is located. The
Tomoscope S works with X-rays. It looks a bit like an oversized microwave and has a lead door to
protect the operator.

Industrial 3D CT scanner from Werth (Tomoscope S)

A 3D CT scan works like this: The X-ray radiation is directed onto the part. The X-rays go through the
object and project an image onto a detector inside the CT Scanner. The part is placed on a turntable
that rotates slowly. This allows the object to be X-rayed from all sides. From these 360° sectional
images, a 3D model can be generated. In the end, the finished 3D scan can be exported in the STL
file format.

Reverse Engineering of the Part

Secondly, we digitally reconstructed the object using software. During this process, we had the
opportunity to repair the faulty part. Thus, we were able to digitally restore the broken corners of
the clothes rail brace to their initial state. “Reverse Engineering” is the technical term for the
conversion from a 3D scan (STL format) into a CAD model (STEP format).

Reverse engineering of the IKEA clothes rail brace

Deviation Analysis

To investigate how far the reverse engineering of the clothes rail braces deviates from the original
3D scan, we created a deviation analysis. For this purpose, we use the free software “Zeiss Inspect”.
The green color indicates that the reconstruction is deviating very little from the original 3D scan.

Deviation Analysis, which compares the 3D Scan against Reverse Engineering. You can download the
deviation analysis here.

3D Printing of the Repaired Part

Next, our repaired clothes rail brace was 3D-printed. There are different 3D printing methods. We
have chosen the laser sintering process (SLS) because it produces very flexible and durable parts.

Industrial 3D printer “Formiga” uses the laser sintering (SLS) method

With the laser sintering process (SLS), on the other hand, the model is built up in a powder bed. The
laser first melts the contours of the object into a thin layer of powder. Then another layer of powder
is applied by a machine, and the laser fuses this layer precisely onto the previous one. This process is
repeated until the entire part is finished. In the finished piece, a fine stair-step pattern is visible;
these are the separation lines between the fused layers.

Removing the 3D-printed Part from the Powder Bed

After 3D printing, the part is inside a powder bed. The finished part must be dug out of this powder.
The surface of the part is sandblasted. Sandblasting smoothes the surface and removes any powder
remnants. In a final step, any remaining dust is blown off.

The repaired clothes rail brace fits perfectly into the closet

Project data for Download

We have provided the deviation analysis and the download link for the Zeiss Inspect software.

Conclusion

The reverse engineering and repair of the clothes rail brace worked wonderfully. The better the 3D
scan of a part, the easier the reverse engineering. In this case, we were able to work based on an
extremely accurate CT 3D scan. Surely this project could have been realized with simpler technology,
but it is an excellent example of what is possible.

Do you have a broken part that you want to repair with 3D scanning and 3D printing?

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Deviation analysis (nominal actual comparison)

Swann Rack — Sat, 01 Aug 2020 16:11:21 +0000

Example 1: Deviation Analysis for Quality Control in Production

If a company manufactures metal gears, every day, the factory produces 1000s of gears. Six gears
are taken at random from the production line, and then 3D-scanned. From the time the gear is
initially designed, there is a CAD model. The CAD model is a 3D file with all dimensions of a perfect
gear. This CAD model is compared with the 3D scans from the production line. This is a “nominal
actual comparison”. It is a deviation analysis that shows how much the gears from production
deviate from a perfect gear. Based on this analysis, the engineers can optimize the gear production
machine to improve manufacturing quality.

Gear 3D Scan (left) and gear reverse engineering with solid modeling (right)

Example 2: Deviation Analysis for Quality Control in Reverse Engineering

A part is first 3D-scanned, then a reverse-engineered model is created from this 3d scan. However,
the reverse engineering process can only approximate the 3D scan. The differences between the 3D
scan and the reverse engineering are then analyzed and visualized with a deviation analysis and a
false color comparison.

Front view of a gear; deviation analysis of 3D Scan and CAD model

Deviation Analysis in Four Steps

Import of the nominal data (e.g., CAD file of the perfect gear).
Import of the actual data (e.g., 3D scan of the manufactured gear).
Both data sets are superimposed in the analysis software (Zeiss Inspect)
The data sets are compared, and a deviation analysis report is created. The differences are
visualized with a false color comparison.

Side view of a gear; deviation analysis of 3D Scan and CAD model

Deviation Analysis Report

Two 3D models are superimposed using the analysis software “Zeiss Inspect”. The differences
between the two data sets are displayed in color. Different colors correspond to positive and
negative deviations. On the right side of the report, there is a legend showing a color gradient. Red
means that the actual data is above the nominal data. Blue means that the actual data is below the
nominal data.

Software Zeiss Inspect for creating a deviation analysis or nominal actual comparison report

The best software to create a deviation analysis or nominal actual comparison report is
Zeiss inspect. Zeiss is a company that builds predominantly 3D Scanners but also makes great
software.

Zeiss Inspect (Software for creating a deviation analysis)

Do you require a deviation analysis with your reverse engineering project?

Holocreators offers 3D scanning services, 3D scan-to-CAD conversion services (STL to STEP), 3D modeling services, and CAD design services. We would be happy to assist you with your project. Please call us at +49 40 481133 or send an email info@holocreators.com

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Lecture on 3D-scanning and spare parts

Swann Rack — Sat, 01 Aug 2020 00:16:32 +0000

The “Sustainable Design Center” and the Federal Office for the Environment were interested in showing the audience how to repair damaged household appliances using 3D scanning and 3D printing, instead of throwing them away.

Swann Rack gave a lecture at the Sustainable Design Center in Berlin

For example, a small gear breaks in a kitchen appliance. How do you 3D-scan and 3D-print the gear to repair the kitchen appliance?

During his presentation, Swann Rack also talked about the professional 3D metrology equipment Holocreators uses to 3D-scan parts. This includes photogrammetry, structured-light scanning, laser scanning and computed tomography.

Do you need help with your reverse engineering project?

Holocreators offers professional 3D-scanning and reverse engineering services. We would love to help you with your project, so feel free to get in touch. Give us a call at +49 40 481133 or send an email info@holocreators.com

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What is a Point Cloud?

Swann Rack — Fri, 12 Jun 2020 00:47:35 +0000

How Can You Look at a Point Cloud?

You can view a point cloud with a free 3D viewer. Depending on the file format you want to look at,
you’ll need an appropriate viewer. These are our free favorites:

This is what a point cloud looks like in CloudCompare

Hardware Requirements for Visualization

Point clouds can consist of millions of points. Therefore, a powerful computer is needed to visualize
large point clouds. Point clouds have a very raw character since they are only a collection of points in
the coordinate system. With a 3D viewer, the 3D object appears half-transparent because you can
look through the captured points.

When zooming into the point cloud…

…you can see that the point cloud…

…is made from thousands of points.

How Are Point Clouds Processed Further?

Depending on the application, point clouds are filtered, for example, to extract points with specific
parameters. In most cases, however, point clouds are converted into a polygon mesh. There are
many names for this conversion, such as “meshing” or “polygonization”.
The conversion of a point cloud into a polygon mesh can be done by running software that connects
all the points to form a mesh of triangles (polygons). The converted file is then exported in the STL
file format. If colors are present in the point cloud, they can be output as a color map (file format for
color: OBJ + JPEG).

Polygonization: Points are connected to form polygons

What Are Some Point Cloud File Formats?

The simplest file format for a point cloud is XYZ. It stores all points as (XYZ) values in a huge text file
(ASCII text format). This file format is advantageous because it can always be read and is, therefore,
future proof.
A big disadvantage of the XYZ format is that colors, intensity and vectors are not stored. Due to this
limitation of parameters, much information is lost.
Therefore, many 3D scanners and software companies have created their own point cloud format to
store the data more efficiently.

Here are some relevant open point cloud file formats:

*.xyz
*.ply
*.las
*.e57
*.pts

Swann Rack answers the question: What is a point cloud?

Conclusion

Point clouds are the first elementary step in digitizing an object. The point cloud represents the
measured values of the 3D scanner in a raw form. Based on this information, further steps can be
taken depending on the application.

Do you need help with the processing of a point cloud?

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What reverse engineering tools are available? (3D scan + CAD)

Swann Rack — Thu, 11 Jun 2020 11:03:58 +0000

What Types of Reverse Engineering Tools Are There?

There are numerous reverse engineering tools that you can consider. Here is a selection:

Why is Geomagic Design X the Industry Standard?

Geomagic Design X, formerly known as Rapidform XOR, is the industry standard in reverse
engineering. Numerous wizards help with each step of the process. It also has a powerful automatic
reverse engineering function called “Autosurface”.
Geomagic Design X also provides the best tools for reverse engineering to parametric model with a
history tree. Based on sectional views from a 3D Scan (STL), the outline of the object can be traced
for optimal reconstruction.

Swann Rack explains the different reverse engineering tools that are available.

Which CAD Software Does My Client Use?

Regardless of which reverse engineering software you use, you always must consider which CAD
software the client is using. This is especially important if the client wants a parametric CAD model
with a history tree. The transfer of the history tree between the CAD programs of different software
companies is difficult. It is, therefore, important to become familiar with multiple reverse
engineering programs because only then is it possible to perform reverse engineering with
parametric modeling using the same software as the client.

What is Live Transfer?

“Live Transfer” is the name of a Geomagic Design X tool that allows the history tree to be transferred
to an external CAD program like Solidworks. “Live Transfer” is enhanced with each release of
Geomagic Design X, but sometimes the transfer to Solidworks does not function properly. This is the
case, especially if the part has a complex geometry. We recommend that you do the reverse
engineering using the same software as the customer. For example, if the customer uses Catia and
wants a parametric CAD model with a history tree, then reverse engineering directly in Catia is
recommended.

Conclusion

Learning a new reverse engineering tool is not easy. Nevertheless, our philosophy is: You should
always learn the industry standard as soon as possible. The software, which is the industry standard,
always has the best tutorials on YouTube. But keep in mind, if you don’t plan to use the software
every day and you only need it for a single project, then it’s advisable to hire a reverse engineering
company.

Do you need help with your reverse engineering project?

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Combining 3D-CT scanner and photogrammetry

Swann Rack — Wed, 10 Jun 2020 20:44:46 +0000

What is Photogrammetry? And What is a 3D CT?

Photogrammetry and a 3D CT are two different 3D scanning techniques. In photogrammetry, the 3D
scan is calculated from photos. The object is photographed from all sides, and software generates a
3D model.

3D CT X-ray sectional image animation

Inside the 3D CT Scanner (also known as 3D computed tomography), X-ray sectional images are
taken from all sides of the object, and the 3D scan is calculated from these images.

Walk-in 3D CT (computed tomography 3D scanner) at the Fraunhofer IIS.

Fusion of Both Techniques

Both photogrammetry and 3D CT scanning have their advantages and disadvantages. With the fusion
of both techniques, we want to combine the strengths of both systems.

The biggest advantage of photogrammetry is that it creates a colored 3D model
The biggest advantage of 3D CT scanning is that it measures very accurately and that it also captures the interior of an object

By fusing of both techniques, we get a highly accurate colored 3D scan.

Inside the walk-in 3D CT—a photogrammetry set-up consisting of DSLR cameras and lights

Research Project Cooperation

For this research project, we cooperated with the Institute of Technology Deggendorf and the
research institute Fraunhofer IIS. These institutes research the application possibilities of industrial
computed tomography. As a first feasibility study, we 3D scanned a shoe.

3D CT software that controls the computed tomography 3D scanner

How Does the 3D Scan Work?

The shoe is placed on a turntable and photographed by three cameras. After a triple set of pictures
has been taken, the turntable rotates a few degrees further, and the cameras take another set of
pictures. The result is a set of 72 images from many different perspectives, from which a 3D model
can be calculated using photogrammetric software. For the next step, the 3D CT scanner is switched
on, and the shoe is x-rayed. Both 3D scanning techniques are performed one after the other and
without moving the shoe.

3D CT scan of a sports shoe without color

Merging Two 3D Scans

The recording process results in two 3D scans. One with color, created by photogrammetry and one
created using 3D computed tomography. Both data sets are merged. The color information of the
photogrammetric 3D scan is projected over the 3D CT scan. This fusion results in a highly accurate
3D scan with color.

Fusion of 3D CT and Photogrammetry produces a highly accurate 3D scan of the sports shoe with
color

Project Data for Download

We have prepared the unprocessed 3D CT scan, the photogrammetry photos and the finished 3D
scan for you to download.

Conclusion

The fusion of photogrammetry and 3D CT is ideal for creating highly accurate 3D scans of an object
with color. If we find a way to automate the recording process, as well as the data processing, this
3D scanning technique could be relevant for 3D product photography.

Do you need a 3D CT scan with color?

Holocreators offers 3D scanning services, 3D scan-to-CAD conversion services (STL to STEP), 3D modeling services, and CAD design services. We create 3D scans with computed tomography (3D CT) and photogrammetry and thus can offer your highly accurate 3D scans in color. We would love to help you with your project. Please call us at +49 40 481133 or send an email info@holocreators.com

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Wire EDM for cutting metal 3D prints

Swann Rack — Mon, 08 Jun 2020 11:11:11 +0000

How Does Wire EDM Work?

The wire EDM machine works like a precision band saw. However, the interesting thing is that the
“saw” never touches the workpiece. The wire EDM machine has an extremely thin brass wire, the socalled “EDM wire”. This produces up to 1 million electric sparks per second. These sparks erode the
workpiece and carefully separate the 3D metal print from the base plate.

Metal 3D print cut by wire EDM

The EDM cutting process takes place in deionized water. This means that all minerals have been
filtered out so that the water no longer conducts electricity. The EDM wire is positively charged, and
the workpiece is negatively charged. The water (dielectric) isolates the electric current between the
two. When the machine is switched on, the wire is moved closer and closer to the workpiece until
the insulating ability of the dielectric (water) is no longer sufficient to insulate the electric current
between the two parts. The spark jumps over and melts and vaporizes the metal on the wire and the
workpiece. This is the reason for the beautiful, precise cut in the metal. The machine continually
feeds new wire because the wire can only be used for one cut.

Empty water tank of the wire EDM machine

Advantages of Wire EDM

Due to the thin EDM wire and electric sparks for cutting, the cut in the metal workpiece has a
diameter of only about 0.5 mm. This is much thinner than other cutting methods. Wire EDM can cut
all metals that conduct electricity, no matter how hard they are. At the Fraunhofer IAPT, for
example, they print almost exclusively in titanium, a very strong metal. Other tools would have
difficulty cutting through titanium, but with wire EDM, this is not a problem.

Thin EDM wire of the wire EDM machine

Disadvantages of Wire EDM

The biggest disadvantage of wire EDM is the cost and slow cutting speed. The EDM wire can only cut
through approx. 50-100 cm of metal per hour. Also, the maintenance costs, consumables and
electricity are much higher than with other cutting methods.

Used wire of the wire eroding machine

Conclusion

Wire EDM is the perfect cutting technique to cut through all electrically conductive metals. The cost
is high, but no other cutting method achieves similar clean cuts. In metal 3D printing, it is used to
detach the workpiece from the base plate.

Do you have a metal part that needs to be cut by wire EDM?

Holocreators offers 3D scanning services, 3D scan-to-CAD conversion services (STL to STEP), 3D modeling services, and CAD design services. We also have extensive experience with metal 3D printing. We would love to help you with your project. Please call us at +49 40 481133 or send an email info@holocreators.com

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Metal 3D-printing with selective laser melting (SLM)

Swann Rack — Mon, 08 Jun 2020 00:07:25 +0000

How Does Selective Laser Melting Work?

The process starts with a base plate. A scraper moves back and forth and spreads metal powder on
it. The laser then melts the powder only at the points where the object is to be made. At these
points, a solid metal part is created, while the loose powder remains. This process, known as
selective laser melting (SLM), is repeated layer by layer until the complete object is finished.

The laser melts the metal powder only where the part is to be created

The metal powder plays a central role in selective laser melting (SLM). To produce a part, not only
must the correct powder be used, but the base plate must also be made of the same metal as the
part itself. The part is built up layer by layer. Each layer is only 0.03 mm thin. This means it can take
up to 30 to 40 hours to produce a large part using SLM. During this time, the machine melts
countless layers of metal powder.

Metal base plates on which the parts are created with metal 3D printing

Why Is a Supporting Structure Needed for 3D Metal Prints?

If the part to be printed has overhangs that cannot be supported by the powder inside the 3D
printer, then a supporting structure is required. As a rule of thumb, if the overhang is more than 45
degrees, a supporting structure must be added. This support structure holds the part during the 3D
printing process so that it does not sag or deform.

Metal 3D printed part with a support structure

After the printing process, the remaining metal powder and the supporting structures must be
removed. Parts made with 3D metal printing have a rough surface. Holes or threads cannot be
printed directly but must be drilled separately, such as with a CNC milling machine.

Finished metal 3D printed part without a support structure

Conclusion

Selective laser melting (SLM) is a metal 3D printing process. It can be used to create metal
components that are not possible with any other manufacturing process. In particular, complex
internal structures such as cooling channels can be integrated directly into the part. The costs for
metal 3D printing are very high compared to traditional manufacturing methods such as CNC milling.
For this reason, metal 3D printing has so far only been used in rapid prototyping or very small
production runs.

Do you want to 3D print a part in metal?

Holocreators offers 3D scanning services, 3D scan-to-CAD conversion services (STL to STEP), 3D modeling services, and CAD design services. We are also very experienced with 3D printing, and we would happily advise you how to 3d print your part in metal. Please call us at +49 40 481133 or send an email info@holocreators.com

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