6. 3D Scanning and printing

This week’s assignment was:

group assignment:
   group assignment:
      - test the design rules for your 3D printer(s)
   individual assignment:
      - design and 3D print an object (small, few cm3, limited by printer time)
         that could not be made subtractively
      - 3D scan an object (and optionally print it)

Designing My Object

I decided to 3D print a bearing for this week. I knew that this bearing would not be very good considering that there would a lot of friction. I started off by looking at some other bearings that other people have made using 3D printers. For example, there was this cross roller slew bearing tutorial on YouTube.

However, I decided to design a regular ball bearing. I referenced this guide. It was simply showed me a very useful cross section diagram of a ball bearing.

I simply extruded the inner race and outer race to the parameter I set for my bearing height. A new plane was added with a sketch of how large my ball was in relation to the inner and outer races.

I used this circle as reference to find out where the balls would contact the race. I wanted only four contact points so I used four tangent lines with a few arcs to shape my hole to the desired size.

A separator for my bearing was then created by extruded a sketch in between the two races by cut extruding out the spheres and extending the cut until it reached the bottom.

The separator and the balls were extruded as STL’s locally by right clicking the bodies and clicking “Export as STL.” However, this only works for single bodies and since I wanted to print the inner and outer race as one piece, I had to have Fusion convert my file into an STL over the cloud.

The 3D printer I used was a LulzBot TAZ 6 and the software was Cura LulzBot. Simply import your desired file to 3D print and tinker the settings to your desire. There are advanced settings in the Print Setup that can be configured besides from the already recommended ones. In this case, I chose to use a 30% infill in addition to generating supports for my races. It was also scaled up 10x.

The print came out well and I decided to print my balls using the high detail mode with only a 20% infill. These took a bit of experimenting as the extrusion of the PLA made the balls wider than they should have. This was solved by simply scaling them down.

Once everything is 3D printed, simply remove all the supports and position all the pieces to where they should be. The balls will be inserted using the side slot made in the outer race and the balls will be held in place using the separator.

The bearing works and can still spin under a bit of load, however, it has yet to spin freely. While a little bit of grease might help, in this case that would be too extreme and messy.

Fusion File:

Scanning an object

The scanner we used was the Matter and Form V1 scanner. This scanner was very old and produced very unsatisfying results. Nonetheless, it was relatively easy to set up. The manual for their new software, MFStudio, was very step by step and provided clear instructions on how to set up the printer.

Physically setting up the printer was different. Since this scanner was old, it required a lot of outside help. For example, our lighting had to be really good for our scans to come out even decently well. A little booth for the scanner was created to make the lighting better.

To scan, simply just place your object on the rotating platform of the scanner, set the desired height for the scan, and press the “+ new scan” button.

I did a rocket the first time and with this, you can see a few caviats in the printer.

It picked up the outer edge of the fins, but not the inner faces of the fins. The scanner moves in a 360 degree motion only picking up things on the outer edge of your object. This means that things that are circular or oblate in shape will have the best results when scanning.

To see a completed version of your object, simply go to the Mesh tab and click the Mesh button. This will take a while but will mesh together all the points that the scanner made to create your final object. This is how it turned out:

I did this again with another object and the results were about the same.

Since the scans were very bad and had a lot of spots that were unscanned, I decided that I would not export the scans.

Here are the files for this week: download

Group Project

The group project documentation for this week can be found here.