Transcript:
Hi, my name is Swann with the 3D-scanning company Holocreators. And today I want to show you, how to make a reverse-engineering of a mechanical part with free software. So we took this part here and 3D scanned it and in this tutorial I will show you, how to take the 3D scan of this part and turn it into a CAD file. So STL-file to STEP-file conversion. And there you can see how the 3D Scan is turning – that is the polygon-mesh, and afterwards you can see the CAD-file. That is the reconstructed part. How does it work? Well, I will show you the seven steps which are needed to make this reverse-engineering. You will need two free software packages, you will need Netfabb – that’s for taking measurements on the STL-file, on the 3D-scan and you will need FreeCAD, that’s for reconstructing the part in CAD. This is a rather basic tutorial now, if you want to know how to do it in detail – click-by-click – we also have a two hour tutorial prepared, where you can really follow from the beginning to the end how to reconstruct this part here. So, this is more of a basic overview. Step number one is taking measurements in Netfabb and creating a reference sketch in Free CAD. Here you can see the UI of Netfabb. First we make a new measuring. And then we click on the “Measure radius” – please pay attention to also activate the button “Three points on circle”. And then, on the outside of this flange, we select three points and Netfabb will automatically create the measurement and tell us, that it’s 75.97 millimeters. So let’s make it an even 76 millimeters. Then we go back to Free CAD and create a reference-circle. And define the circle radius, which is 76 divided by two, and now we have our reference-circle. Step two is making a correct placement of the 3D-scan inside FreeCAD, because right now the scan is not properly orientated, so it’s like THIS inside the 3D-realm. And we will adjust the part, so that it’s perpendicular to the axis. We go into Free CAD and click on “Placement” down in the menu, and then on the three dots, and then we click on “Apply incremental changes to object placement”. Then we change into a side-view and we orient the part until its perpendicular to the X-axis. Then we change the view and change the 3D Scan so it’s also perpendicular to the Y-axis and then we change to the top-view and make sure that it’s within the center of the circle. Step three is change the transparency of the 3D-scan inside Free CAD and create a profile. This is, so that we can construct on the side-view of the 3D Scan. In Free CAD we press Ctrl+D to enter the transparency menu and set the transparency to about 60 percent. Then we create a new sketch and choose the X/Y axis as the layer. And then we start sketching on the cross section of the flange. And we have to define the constraints. And that is by adding the measurements. So, we remember the radius was 76 divided by two, so, 38 millimeters and we type that in, and now it’s constrained. And now we have to switch a lot of back and forth between Netfabb and Free CAD until the sketch is fully constrained and then it will be green and then we can use it to rotate the profile and create our flange. Step four is hiding parts of the polygon-mesh to construct on top of the cross section. In FreeCAD, you click on the scissors-symbol and then you have this blue line with which you can choose the area that you want to hide. You do a right-click and click on “Inner” and then you have this cut-view and then you can create a new sketch, a new plane, and then go into the menu and adjust the Z-value until the new layer is at the same height as the cut and then switch into the top-view and create a new sketch and then it’s like last time, creating a sketch and making it fully constrained, so, it’s finished. In step five we are connecting all the profile sketches with the loft command, to create a new part. In Free CAD you can see all the different profile sketches that we made. For simplicity reasons, we are only going to use the outside ones. And then we click on the “Loft” command and select the profiles one-by-one and then we have our part. In step six we connect all the parts with the Boolean-operation and finally export the file as a STEP-file. In Free CAD now you can see all the different parts, which need to be combined. All these parts have been made with the different modeling techniques, and we select them one-by-one until they are all green, and hit this button with the two circles, the Boolean-operation. And then we can go to “Export” and save the file as a STEP-format. And then the part is complete. Step seven. This is a, kind of, quality control. So we have created our new CAD-file and now we want to compare it with the 3D Scan. We want to see how precise we worked and how much difference there is between the original 3D Scan and the new CAD-file. For this, we use a software called: “GOM Inspect” – you can also download this software for free, I will put the link into our blog – and this will allow us to overlay both parts and see how much deviation is between them. This is the UI of GOM Inspect. Here you can see the overlay process, where we overlay the 3D Scan with the STEP-model that we created. And then we can see, the different colors show us, how much the deviation is between both parts. So these were the basic seven steps, how to make a reverse-engineering using free software. If this went to fast, you can always go back and look at the individual steps. If you want to know it in more detail, we have prepared a two hour tutorial, which I will also link inside the blog and inside the description of this video. If all of this is too much hassle for you, we are happy to help, as I said, we are a reverse-engineering company and 3D-scanning company, so we always like to help you with your projects. Otherwise – have a great day and see you next time. Bye, bye!