Scan to CAD to Print – A Reverse Engineering Journey
Introduction This blog is going to take you through each of the steps required for reverse engineering components from scan to CAD to print. Original Component The first and most obvious part of the process is obtaining the original component …
This blog is going to take you through each of the steps required for reverse engineering components from scan to CAD to print.
The first and most obvious part of the process is obtaining the original component that you want to be scanned. Before scanning the part preparation may be required to obtain a quality scan of the object. When does a scanned part require preparation? This is dependent on the type of scanner being used and the components surface, colour and material.
If you are using a white light/structured light scanner then part preparation is more important. If the part you are wanting to scan has shiny, dark or clear surfaces then they will require preparation. This is because if the light emitted from the scanner hits shiny or transparent surfaces then the light is dispersed and is unable to be captured or created messy scan data. If surfaces are too dark then the light can be absorbed and again the scanner won’t be able to detect the reflected light.
What preparation is required? In cases where the object has an reflective surface such as chrome or the material is very dark or transparent then you can use matte sprays specifically designed for 3D scanning difficult surfaces. The matte spray coats the part in a matte finish which is easy for the scanner to pick up surface reflections and can be easily wiped off the component once you have finished scanning.
Another form of preparation may be required to help the scanners detect the object being scanned. Small circular reflective stickers called targets can be placed either directs on the object being scanned or on the bed that the object is placed on. These targets help the scanner triangulate and pick up the objects surface positions. Targets are typically placed directly on larger objects whereas targets are placed on the scan bed when scanning smaller objects.
Now the part is ready to be scanned the parts data can be captured. Before scanning your part it is import to calibrate the scanner to ensure highly accurate scans. With handheld scanners you want to ensure that the scanner is held the optimum distance away from the object to capture that data correctly. Slowly working your way around the object you want to ensure that you have captured as much information from the scan as possible. Using the scanning software that comes with the scanner you can visually see the data being captured and the areas which require further scanning. Using a turn table with targets on for smaller objects allows you to easily rotate the object without changing its position in relation to the targets making it easier to capture the objects surfaces.
Once the scan data has been captured it often requires the data to be processed to allow for smooth transition when importing the scan data into a CAD software such as SOLIDWORKS. Intermediate software for working with scan data such as Geomagic is required to help clean up the data and help align axis’s, apply planes and sketch profiles to aid the use of scan data in CAD software. Scan software such as Geomagic allow for easy export of a variety of file formats including .IGES, .STEP and .dxf.
Once the scan data has been processed and prepared, it can be imported in CAD software such as SOLIDWORKS for the design stage. The prepared scan data this can be used to assist with the design phase ensuring that geometry is modelled correctly. It is not always essential to re-design the part in CAD however if the object you are scanning has defects or has worn over time then there may be deviation between the scanned data and the original design intent CAD model.
Export to STL
Once the design phase has been finalized and the CAD data is complete it is ready to be exported to a file format that is compatible with 3D printing slice software. Depending on the slice software several file formats can be accepted however the most commonly used file format is STL.
Setup Build Parameters
Inside the 3D printers slice software you are able to set parameters such as material, orientation and various other settings. Most 3D printers come with their own slice software however if not the most commonly used open source slice software is Ultimakers Cura software.
Manufacture the Component
After having set the required print parameters in the slice software ensure that the printer is all set up correctly. The set up required will vary depending on the printer but once you have checked materials etc. you can send your file to the printer and start the print.
Finally once the part has finished printing it may require post processing such as removing support material. Certain 3D printing processes like SLS, require less post processing as the part is self-supporting it doesn’t require support removal. Other processing such as SLA often require washing curing to ensure that the materials full mechanical properties are achieved.