CAD Scanning: A Comprehensive Guide For Beginners

Scan to CAD involves scanning a physical object and then inputting the data into CAD software. Scan data serves as a guide for engineers for sketching CAD drawings. 3D scanners capture all details related to the geometry of products, eliminating guesswork from the scanning process. There are several benefits of CAD scanning. It reduces product development costs and also speeds up product design and development.

If a part is no longer in production and you do not have the original CAD drawings for it, scan to CAD is the quickest and most effective way to create a 3D CAD model (especially if it's a complicated part).

Design engineer working on CAD drawings.

Can a 3D Scanner Directly Output a CAD Model?

Reverse engineering a cookie mold. Part scanning and modeling

No, a 3D scanner cannot directly create a 3D CAD model because 3D scanners generate point clouds or mesh data that cannot be automatically converted to CAD surfaces. Simply put, the 3Dscanning software cannot understand what a scan represents

3D scanning projects, especially projects that involve scanning larger objects, can be very complicated. Regardless of how minor it may seem; a 3D scanning mistake can lead to inaccurate results and erroneous conclusions.

Why Use a 3D Scanner to Create a CAD Model If It Will Be Recreated Anyway?

Creating a CAD model when you do not have a ready reference can be an overwhelming project. It may take several attempts to create a model you’re happy with. Instead of starting with a blank canvas, why not leverage data captured by a 3D scanner? Scan-to-CAD is more efficient than designing from scratch and can save businesses time and money. Using the process, you can get an accurate representation of parts. Also, scan-to-CAD generates invaluable insights that you can use when designing products. A 3D scanner simplifies the reverse engineering process.

Parametric modeling. creating a solidworks model from scan data

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Scan-to-CAD Workflow

The scan-to-CAD workflow consists of the following steps.

Making Scan Data Usable

After data is captured, it should be cleaned. CAD scanning services use advanced software to decontaminate raw scan data. The process may involve removing errant points from the cloud, resampling, and filling in any holes. In the second step, 3DCAD scanning services convert individual points to a mesh, with each point representing a vertex of a triangle

Reverse engineering with CT data

Once the CAD model is sanitized and meshed, you can directly import it into CAD software. If no further modifications are required to be modeled, you can directly export meshes for slicing and 3D printing.

Converting the Meshed Scan Into a Solid

Reverse engineering with CT data

The mesh is  then cut using a  polyline generation tool. This is the most complex step in the process. Because no tool can create primitive-based solids or spline directly from a mesh, the process must be supervised by humans. If the model is relatively simple and consists of basic primitives, the solid can be manually created using the mesh as a reference.

For objects with complex surfaces and compound curves, engineers use the mesh as a reference and cross-sections as templates to create spline contours of the solid model. When used correctly, both these techniques can help ensure the accuracy of solid models.

How to Properly Scan Holes and Deep Grooves?

laser scanning and modeling golf clubs

It's challenging to scan features such as holes, deep grooves, and gaps, as the only part of the inner wall that will be scanned is just around the top. Before scanning holes, plug them and leave some part of the plug exposed to simplify the scanning process. In the case of deep grooves, keep the scanner’s line of elements parallel to them to capture more data.

How to Prevent Common CAD Software Problems?

3D scanning and reverse engineering a punch

Here are some common CAD software problems and how to prevent them.

  • Corrupted Files: A crash, virus attack, or faulty transfer can corrupt your files, making them unreadable. If your files become corrupted, your hours of hard work could go down the drain. To prevent this from happening, back up your files regularly in the cloud or to an external hard drive. Never open or save files from unknown sources. If, despite all precautions, your files become corrupted, try recovering them using built-in tools. To manage backups, use a data management solution that saves different versions of files. Enable ‘Autosave’ so your work gets saved automatically.
  • Missing References: Sometimes, externally referenced files such as images and blocks can go missing. As a result, your files may display incorrectly. To prevent this problem, keep your external files and main file in the same folder. Alternatively, use relative paths rather than absolute paths. Use the purge or audit commands in your software to eliminate unused or invalid references. Try locating missing references manually or use the Find and Replace command to update them.
  • Incompatible Formats: If your CAD software doesn’t support the format of your file, it may not open. Check the format and version of your file and make sure your software supports it. If your file isn’t compatible with the version of the software you’re using, try opening it using a different software or request the file owner to share a compatible version.
  • Invalid Commands: Invalid or incorrect commands in a file can result from a typo, a syntax error, or a logic error. A file containing an incorrect command may not execute properly. To prevent this problem, always check the syntax of your commands and ensure they do not violate any rules established by your software. Try using a debugging software, or the command line/the code editor to debug or edit incorrect commands.

To prevent CAD crashes and glitches:

  • Make sure your system meets the minimum requirements to run the software.
  • Keep your software and drivers updated
  • Regularly clear your cache and temp files
Clarinet mouthpiece. STEP model created from CT scanning and reverse engineering

NelPreTech specializes in CAD scanning. Our ability to tailor 3D scanning solutions to our customers’ unique needs sets us apart. To make an appointment, call 708-726-8463.

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