This is part five of a blog series covering how a group of car and engineering enthusiasts are bringing the Tucker Torpedo concept car to life. If you haven’t read the other Tucker Blog entries, please go here to get caught up:
Work on the Torpedo is really picking up! Rob Ida has the ’40 Merc I mentioned in Blog #4 just about finished. The painting has been completed, the chassis assembled, and the body mounted to the chassis. All that remains is the interior fabrication. I should be able to post some pictures of the completed Merc in my next Blog.
Since the last blog a major task was completed: The body was laser scanned by Ron Seaman and Hal Ventres from Capture 3D. Ron and Hal stopped by Rob’s shop and scanned the body using their ATOS Blue Light 3D Scanner. The scanner is capable of capturing highly accurate 3D measurements from a large area, which speeds up the scanning process. The task of scanning the body was necessary so an accurate representation of the body that Rob fabricated is available in order for decisions to be made on how to support the body. The current SOLIDWORKS 3D model of the body was recreated from data used to create the buck and doesn’t accurately represent the “as built” body. We’ll need accuracy when we get to other areas to design that will interface with the body.
Here’s Ron (dark shirt) and Hal (white shirt) from Capture 3D scanning the body. Hal is positioning the scanner for the next scan. You’ll notice the body of the Torpedo has a splotchy look to it. That’s due to a powder sprayed on the body to cut down on the reflectivity of the aluminum. It takes many steps to scan the whole body. In order to provide accuracy for the scans, targets are placed on the body. Those targets are “understood” by the scanning software and used as points to align the series of scans.
The next step for the scan data is to have Andre Clemons start the process of modeling the body using Class A Surfacing capabilities of CATIA. Class A surfacing is a requirement for automotive design because of its curvature continuous (C2) capabilities. C2 eliminates any discontinuity between surface patches at their respective boundaries so the 3D model will look as good as the body on this 1956 Chevy. Everything is smooth as glass and the reflectivity is almost mirror-like.
Here are two examples showing the difference between tangency and C2. The Zebra stripes are used to show any discontinuity between surfaces at their boundaries. When Zebra stripes match at a boundary but change direction, it indicates a tangency condition as seen on the right. When Zebra stripes continue smoothly across a boundary, a C2 condition exists as seen on the left.
Here’s another example of a part having tangency and not C2 at the boundary between the flat surface and the cylindrical surface of this plastic case. You can see how the light forms a line at the boundary. This is what Zebra stripes do for us when working with 3D surface models. We know exactly how the body will look after modeling it.
At this point in time an accurate representation of the “as-built” body is very important. In order to make accurate decisions about the design of the sub-structure supporting the body, the body attachment points to the chassis, and how the front fenders will rotate and what drives and supports them will be based on the new scanned data.
Here’s the scanned data opened in SOLIDWORKS based on the 3D scan:
Here’s a comparison between the original SOLIDWORKS model in green and the scan of the “as built” body in the pinkish color. As you can see there are some major differences between the two. These differences would have caused major problems down the road as we continue the build.
Compare the scan-generated model on the left to the original model Andre Clemons modeled on the right. You can see the differences between the two. The data Andre used was from a scan of the plaster model as described in the first blog. The information Rob is using comes from many resources, such as copies of original artist sketches and renderings. With this new knowledge Rob can make better decisions going forward. So a big thanks to Ron Seaman and Hal Ventres from Capture 3D for scanning the Torpedo! We can now move forward with the design and fabrication with confidence!
In the next blog I hope to be able to show you how the body and chassis will come together. Bob Cuneo has the chassis about finished and I’ll update everyone on that also. Stay tuned!