3. 3D printing#

Table of Contents

In this week’s module, we learned how to use 3D printing programs and 3D printers and we printed the pieces we designed last week.

Prusa Slicer#

First of all, we had to install the Prusa Sclicer software which allows you to print the CAD files. There are several steps to follow and I’m going to list them for you. Here there are summed up :

  • Export the CAD file from OpenSCAD as an .stl file (you must render the 3D model in OpenSCAD first before exporting)
  • Import that file into the PrusaSclicer program
  • Choose carefully the good face which touches the support, if you don’t do it correctly, your 3D model might collapse during printing
  • Select the printer and the settings (infill, layer thickness) depending on the precision or speed you want
  • When needed, put some supports to reinforce the structure or to keep it from detaching from the plate (it’s really annoying to remove them from your part afterwards but it’s required sometimes, see for my piece).
  • Press Slice now and Export GCode. Save the file on a SD card. Take that SD card to the 3D printer and start printing! Be careful, you need to first clean the board with alcohol before printing.
    Steps

Characterizing the design parameters#

I explained the usefulness of parametrization in my last module, go check it out!
This was the first piece I printed, you can see the result below. It turned out that the best parameters for the cross pin hole are 5mm in length and 1.87mm in width.

Printing of my part and a compliant piece#

Common issues#

For the common issues, I recommend you to read this GitLab documentation.

Barrel#

I then proceded to print my part (the barrel). That’s where I encountered the limits of 3D printing in terms of structure stability. As you can see in the left image, the top part of the barrel is basically free and has no support. This leads to structural problems. To prevent that, PrusaSlicer provides as an option to add supports to the structure which are then removed by hand afterwards. However, this process is not very optimized (or I just didn’t use it correctly). Indeed, when I printed my piece it not only had structural problem as you can see on the left but the supports also filled up the hole I programmed to attach the rope… So it was a double fail for me. However, my ugly piece still fulfilled it’s purpose so we kept it.
Fail

Compliant arc#

Afterwards, I printed my compliant part (I made one for fun, it’s not part of any mechanism) and I didn’t have no struggles with it. However, I couldn’t test it because we didn’t plan any mechanism to include it. As you can see, the arc doesn’t fully recover it’s original shape. If you use my code from module 2, I recommend reducing the thickness of the arc by reducing the eps parameter.

Testing of the complete mechanism#

Here’s an image of our 4 pieces together :

And here you can see the mechanism built together and in action (props to Nikita for building it on his own !!!):