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5. 3D Scanning and printing

During this week, the assignement was :

  • test the design rules for your 3D printer(s)
  • design and 3D print an object that could not be made subtractively
  • 3D scan an object

At the begining, we have done the group assignement here. My part is the 3. Prusa part.

Hero shot

1. 3D printing

1.1. First attempt

To test 3D printing, I first chose a simple shape: two nested circles. This will enable me to make a simple object that can only be made additively because of the intertwining of the two parts. I created this shape in FreeCad, then in mesh-it and exported it as a .stl file in Cura to cut it out. I set the resolution to 0.2mm, added an adhesion support and printed it in PLA on the Prusa i3 mk3 printer.

But I forgot to put a proper support (not just a bonding support) for the two rings, so one of them came off during printing and it was a mess.

So I tried again, but this time with a support.

The result was convincing, but I felt it wasn’t precise enough, so I tested the 0.1mm.

The result is much better, so I can continue with more complex shapes.

Here you can find the FreeCad file

Here you can find the .stl File

1.2. Some part for my final project

1.2.1. First design

At the top of my reactors, I’ll have a non-return valve so that excess air in the reactor can escape, but no outside air cant enter the tank. To design this object, I split it into 3 parts: the lid, the tube and the transverse joint.

I designed the part using FreeCad with one constraint: the printed parts must require as little support as possible, to simplify the process. These parts were printed in PLA, in a thickness of 0.1mm, with a tree-shaped support.

At first I miscalculated the length of the holes, so they were blocked by the PLA.

Once this problem was solved, everything worked fine! But there’s still room for improvement.

1.2.2. Inclusion in a bigger part and adjustments

A first improvement is to shorten the part where the lid and tube connect, because the space allows the parts to move and lock in a position where the lid is not closed.

I also wanted the flap to fit inside the lid. So I designed a part that would fit inside the larger one, without a proper junction so far.

Now all I have to do is make an improved resin version with threads and a seal between the cover and the valve.

Here you can find the FreeCad file

Here you can find the lid .stl File

Here you can find the tube .stl File

Here you can find the junction .stl File

2. 3D scan

For this part, I was helped by Nicolas KAUFMANN and the other Agrilab students.

To do the scan, we use the EinScan-Pro by 3D shining. First of all, we put the scanner on a tripod, so that we can scan in a fixed position. Next, we place a special plate that can rotate and has numerical symbols to make recognition easier. The scanning technique is using structured light. Structured light is a 3D scanning technique that involves projecting a pre-established light pattern onto an object. By analysing the deformation of this pattern when it interacts with the surface of the object, the system can reconstruct the object’s three-dimensional geometry.

Once the equipment has been installed, we open the 3D shining software. We select the fixed scan, then calibrate the scan with the camera.

We select the number of images we want the system to take, and run it. Everything is done automatically, and the results are given in the scan section. If certain parts are missing, most of the time if there are holes in the object we want to scan, we can redo the scan by changing the angle of the object. Once the scans have been made, the software compiles them and we can move on to post-processing.

In this section, we remove all the parts we don’t want (the scan often includes part of the turntable) and we can make a few modifications: smoothing parts, filling in blanks, etc. Here’s the result of an amonite after all these steps:

Files

Here you can find the circles FreeCad file

Here you can find the valve FreeCad file

Here you can find the circles .stl File

Here you can find the lid .stl File

Here you can find the tube .stl File

Here you can find the junction .stl File