3D Scanning
From the "Homebuilt Cars - from scratch or kits" Facebook group, by Steve Hartig:
"Hey, folks. My name's Steve and I have a 3D scanning business in Milwaukee called Into3D. A friend of mine suggested you all might be interested in a project that I have been working on. We recently started helping out with some sheet metal fabrication for a Cooper-Climax Bobtail. The car we're helping rebuild has some massive front-end damage. The end goal here is to create a sheet metal buck (AKA "whale-bone") in order to form the aluminum panels on the front end of the car.
This is a work in progress, but I have outlined some of the steps we're going through in the pictures. We've never scanned a full car before, but have done a lot of automotive-related 3D scanning and 3D printing projects. Usually we're helping to digitize parts in order to create a CAD model. Our customers can use that in order to duplicate components such as custom exhausts or cylinder head port work.
So, on the Bobtail project, the owner tracked down another car that we could scan that was in good condition. We have a portable scanner on a tripod that essentially takes 3D pictures all around the car. We knit all these pictures together in order to form a scan of the whole car, which we can use to design the sheet metal buck.
Here's what we've done so far:
1.) First, we clean the car and apply temporary target stickers. These stickers are little white dots that let the scanner know what part of the car it's looking at.
2.) Next, we spray the car with talc and clean off the marker stickers. Because the paint on the car is shiny and reflective, it's hard for the scanner to see this surface. Applying a thin coating of talc dulls the surface and makes it visible to the scanner. We then have to go around and clean off the target stickers so that the scanner can see them again. The talc is washable, so it removes easily after scanning is complete.
3.) After the prep work is done, we can start scanning the car. In the picture, you can see that this particular scanner has a limited field of view (shown by the white box projected onto the car). So, we take separate scans all over the car and knit them together afterwards. Each scan takes about 10 seconds, then we move the scanner to the next position and scan again. We take scans everywhere that we need to have captured for our work later on.
4.) After we finish the actual scanning, we import the data into a piece of software called Geomagic Wrap. This software lets us align the separate scans and turn them into an "Exact CAD Surface." Picture #4 shows the scan data when it has been imported and aligned together. At this stage, the data is represented by a polygon mesh known as an STL file. This is the same type of file that some of you might recognize as what you would send to a 3D printer.
5.) The next step is to post-process and "defeature" the scan data. The post-processing removes some noise and imperfections that were picked up by the scanner (such as paint chips, tiny dents, or fasteners). The defeaturing removes items that we don't need on the buck, such as the headlights and mirrors. You can see that this is a lot smoother than the data in the last step.
6.) Next, we convert the scan into a CAD surface. We need this in order to create the 3D model of the buck. Surfacing is basically like taking plastic wrap and stretching it over our scan data. The result is a smooth 3D model that represents the front of the Bobtail. We actually offset the surface by 0.050" to account for the thickness of the sheet metal at this step. This is because we scanned the outside of the sheet metal, but the buck needs to rest up against the inside of the formed sheet metal.
7.) Finally, this is where we are today. I cut cross-sections through the CAD surface every 6". These are each 1/2" thick. These represent the 1/2" plywood that will form the sheet metal buck. We'll send the model to a shop with a large CNC router and they'll cut the plywood sections. Then the fabricator can assemble these into the buck and get started!
So, as I mentioned, this is a work in progress. I hope to get some pictures of the sheet metal work once the fabricator starts putting things together.
I will mention that we quoted this project at $2000 and that our shop rate is $100/hr for scanning, design, and machining work. I spent a little more time on this one than planned, but I developed a pretty good workflow that I am hopeful will come in handy for other customers in the future. I hope you folks find this interesting. I'm not a car builder myself, but auto projects are always my favorite ones to work on. Helping people take their projects to the next level (and finish ones that might have been on hold for years) is really satisfying for me.
Let me know if you have any questions. I'd be interest to see if anyone has done something similar in the past.
Thanks!"
Read More"Hey, folks. My name's Steve and I have a 3D scanning business in Milwaukee called Into3D. A friend of mine suggested you all might be interested in a project that I have been working on. We recently started helping out with some sheet metal fabrication for a Cooper-Climax Bobtail. The car we're helping rebuild has some massive front-end damage. The end goal here is to create a sheet metal buck (AKA "whale-bone") in order to form the aluminum panels on the front end of the car.
This is a work in progress, but I have outlined some of the steps we're going through in the pictures. We've never scanned a full car before, but have done a lot of automotive-related 3D scanning and 3D printing projects. Usually we're helping to digitize parts in order to create a CAD model. Our customers can use that in order to duplicate components such as custom exhausts or cylinder head port work.
So, on the Bobtail project, the owner tracked down another car that we could scan that was in good condition. We have a portable scanner on a tripod that essentially takes 3D pictures all around the car. We knit all these pictures together in order to form a scan of the whole car, which we can use to design the sheet metal buck.
Here's what we've done so far:
1.) First, we clean the car and apply temporary target stickers. These stickers are little white dots that let the scanner know what part of the car it's looking at.
2.) Next, we spray the car with talc and clean off the marker stickers. Because the paint on the car is shiny and reflective, it's hard for the scanner to see this surface. Applying a thin coating of talc dulls the surface and makes it visible to the scanner. We then have to go around and clean off the target stickers so that the scanner can see them again. The talc is washable, so it removes easily after scanning is complete.
3.) After the prep work is done, we can start scanning the car. In the picture, you can see that this particular scanner has a limited field of view (shown by the white box projected onto the car). So, we take separate scans all over the car and knit them together afterwards. Each scan takes about 10 seconds, then we move the scanner to the next position and scan again. We take scans everywhere that we need to have captured for our work later on.
4.) After we finish the actual scanning, we import the data into a piece of software called Geomagic Wrap. This software lets us align the separate scans and turn them into an "Exact CAD Surface." Picture #4 shows the scan data when it has been imported and aligned together. At this stage, the data is represented by a polygon mesh known as an STL file. This is the same type of file that some of you might recognize as what you would send to a 3D printer.
5.) The next step is to post-process and "defeature" the scan data. The post-processing removes some noise and imperfections that were picked up by the scanner (such as paint chips, tiny dents, or fasteners). The defeaturing removes items that we don't need on the buck, such as the headlights and mirrors. You can see that this is a lot smoother than the data in the last step.
6.) Next, we convert the scan into a CAD surface. We need this in order to create the 3D model of the buck. Surfacing is basically like taking plastic wrap and stretching it over our scan data. The result is a smooth 3D model that represents the front of the Bobtail. We actually offset the surface by 0.050" to account for the thickness of the sheet metal at this step. This is because we scanned the outside of the sheet metal, but the buck needs to rest up against the inside of the formed sheet metal.
7.) Finally, this is where we are today. I cut cross-sections through the CAD surface every 6". These are each 1/2" thick. These represent the 1/2" plywood that will form the sheet metal buck. We'll send the model to a shop with a large CNC router and they'll cut the plywood sections. Then the fabricator can assemble these into the buck and get started!
So, as I mentioned, this is a work in progress. I hope to get some pictures of the sheet metal work once the fabricator starts putting things together.
I will mention that we quoted this project at $2000 and that our shop rate is $100/hr for scanning, design, and machining work. I spent a little more time on this one than planned, but I developed a pretty good workflow that I am hopeful will come in handy for other customers in the future. I hope you folks find this interesting. I'm not a car builder myself, but auto projects are always my favorite ones to work on. Helping people take their projects to the next level (and finish ones that might have been on hold for years) is really satisfying for me.
Let me know if you have any questions. I'd be interest to see if anyone has done something similar in the past.
Thanks!"
