Week 5, 3D Scanning and Printing¶

Assignment¶

Group Assignment¶

Test the design rules for your 3D printer(s)
Document your work on the group work page and reflect on your individual page what you learned about characteristics of your printer(s)

Individual Assignment¶

design and 3D print an object (small, few cm3, limited by printer time) that could not be easily made subtractively
3D scan an object (and optionally print it)

Checklist¶

from Nueval

Linked to the group assignment page
Explain what you learned from testing the 3D printers
Documented how you designed and 3D printer your object and explained why it could not easily be made subtractively
Documented how you scanned an object
Included your original design files for 3D printing
Included your hero shots

Group work¶

Print files from “design rules” section of notes for this week.

We split work for the group, which was to print the test files, including printing on different printers. My work was to print the test files with support on a Prusa MK3S+, and my work can be seen on the group page.

Individual work¶

3D scan an object¶

Small object scan¶

As the assignment was to scan a small object, I thought to scan a bottle cap which I could compare to an original, and perhaps even print. As noted in the lecture, a modern phone is capable of 3D scanning, so I elected to use my phone. I checked 3 phones which are available for iOS.

I downloaded all 3, and worked with Scaniverse going forward. Kiri engine complained that my phone was too old to do a LIDAR scan. (My phone is an iPhone 13 mini, which is 3 generations old). 3D Scanner App was difficult to crop a scan, and the use of the front camera was annoying. Therefore, I kept working with Scaniverse.

The images below give overview of key steps.

Install the Scaniverse app
With the camera in the app, align object to be scanned
Hit record, and move the phone. Red strips will disappear as objects are scanned. Stop when the key object lacks red strips
Crop the image (under Edit menu in Scaniverse) to the bottle cap
Process the image when complete. I chose “Detail” to try and get texture
Export the model as STL, which would be appropriate for 3D printing

This results in a model, which I opened in Fusion

When opened in Fusion, this is the 3d model that can be seen. It clearly lacks detail to work as a bottle cap. As noted in lecture, one issue with STL files is that is makes everything as triangles. While this might work well for video games and other object rendering, it doesn’t appear to give appropriate detail for this scan test. While there is the suggestion of a bottle cap, this would not be practical.

I am not going to print this (at the moment), as a better model is needed.

Caveats

There are a couple issues which might have influenced the scan quality.

There could be better lighting. While I positioned the bottle cap in the window, better surrounding lighting could do a better job.
Given my phone is 3 generations old, a newer phone might have better sensors, and do a better job.
There might be better phone apps for scanning. At the moment, I only tried one.
Lastly, and most likely, a phone is not suited for scans of the detail I was hoping to capture.

Larger object scan¶

While my attempts to 3D scan a small object were not productive, this app still appears to do a good job with larger objects. For example, I scanned a chair in my apartment, and it does a fairly good job of rendering.

3d rendered chair

There certainly are artifacts, but this gives a good view of the chair. It was only done in a single pass.

Design and print a 3d object¶

Design¶

My concept is to make a 3d marble maze. There will be an entry and exit for a marble. The maze would need to be rotated to allow the marble to pass. There is a drawing of my concept. There are inset drawings showing how the marble would be allowed to pass or be limited. The pass squares are circles with the diameter of the marble plus a tolerance gap, and the blocked places are squares with width of the marble diameter less the same gap.

This marble maze could not be made subtractively, as the interior passageways have different size openings. Specific structures are needed to either allow a marble to pass, or to block passage. This requires very specific layering in construction, and additive (3D printing) manufacturing is particularly suite to this design.

Marble maze concept.
Green is open to marble, red is closed.

I am starting with a 2x2x2 cube maze as a proof of concept and an initial test. If working properly, it is possible to scale to larger cubes (or other shapes).

I am also tracking the design with squares and circles to track closed vs. open.

The steps taken to make the maze.

I used parameters for all the dimensions, which allows for them to be modified. Critically, I started my design not knowing the exact size of my marble. With a tape measure I put it at 16mm. (Later, I was able to use calipers, and the marble is 15.3mm.) My model assumes individual cube units are 21mm. I started with a gap tolerance of 1mm.

I made a square of 21mm (using the parameter), and subsequently extruded to make a cube in Fusion. To extrude, I extended in two dimensions for 21mm/2. (This keeps the origin at the center of the cube. I used that to help with the next step.)

Using the pipe tool, i made an wireframe of the cube. To accomplish this, I first selected the borders of one face. Then, I used the pipe tool. For that, I made a new body, and used a square shape for my pipe width (3mm). To turn the square into a cube, I used the circle repeat function. I repeated around the axis 4 times, which made the pipe cube. All the piece of the pipe cube were combined into a single body.

To make the full 2x2x2 pipe cube, I used the rectangular repeat function in Fusion. I first made a 2x2x1 version by extending with 2 cubes in two directions (with an offset of 21mm). I then took the 2x2x1 and copied that into the remaining dimension (by 21mm), which made the full pipe cube. I combined all the resulting bodies into a single one.

To make the pass/blocked points, I made a square of 21mm and extruded that to 1mm thickness. I copied that body, and then drew a centered circle of marble+gap size on one. On the other, I made a centered square of marble-gap width. For the rectangle I mades fillets

I then cut these two shapes from the thin shapes, and added a fillet over the inside of the square and rectangle. These separate shapes were useful to double check dimension when printing. (See below).

Circle opening (pass) and square opening (blocked)

I then copied and moved my prototype shapes into positions to create a maze. This was a very labor intensive process, which undoubted could be made easier. (My way “worked”, though I’d want to improve it if scaling to a larger cube.)

In the video, all the steps to make the maze can be seen. It is quite obviously labor intensive with lots of steps.

Maze building steps

The final cube (and the test squares) were exported as STL files for use on the printer.

Printing¶

For printing, I first printed the two squares (open and blocked) to double check the dimensions. My marble passed through the circle version, and not the square. Given that this worked, it was time to move to printing the full model.

The exported STL was imported into Prusa Slicer. The slicer gave warnings about lack of support, and consequently, the full support option was turned on.

After printing, the supports were removed. Or better said, attempts were made. With this cube, it is difficult to remove all the supports. It is still a work in progress, as seen in the photo.

Consequently, though the slicer gave a warning, I printed the model again without supports.

Files¶

Here are the STL files from this work.

Circle (open) wall

Square (closed) wall

2x2x2 marble maze


Scaniverse App	Scanning
Raw scan	Cropped scan
Raw scan	Cropped scan