Sally Williams @ Fab Academy 2015

Note: Assignment for Week 5:

• design and 3D print an object (small, few cm) that could not be made subtracively;
• 3D scan an object (and optionally print it)

Presented and discussed final project development with Tomas Diez during regional review. This was followed in the afternoon with Neil Greshenfeld's introduction to 3D Printing and Scanning.

Assignment: Design of an object for 3D Printing

Slightly intimidated by the week ahead, I eased and loosened my mind into the idea of 3D printing by doing a pastel rendering of a vessel with an enclosed sphere. It helped me consider how I might approach developing certain forms.




However, I do not yet have the skills to create these forms in any of the 3D software packages that I have explored, so this is a little frustrating. Today, some good news, I was finally able to install Solidworks onto new windows partition on macbook (this I completed using Bootcamp Assistant - on Mac, installing the now free Windows 7).

Below, I include some images of various basic 3D files that I tried to generate - and give overall first impressions for each, as I consider developing a form for 3D printing. 


Rhino
Comments: Overall I feel that if I perservered I could get to enjoy working with Rhino. It seems reasonably easy to generate simple and basic forms, and to merge them together. However, as a beginner what I found difficult is how to control these components in space in relation to each other. The Grasshopper plug in is not currently avalable on Mac.

  


Blender
Comments: Although I did not have more than a few hours trying Blender, I could see how this software was very powerful and had an effective graphic interface. I liked the 'dots on planes' feature from which you can pull controlled fragments out of the basic form you start with. This might be an application that really supports a creative and visual workflow, less technical in approach and more potential to explore forms. Its an interesting way of thinking. It also makes apparent how architecture has been able to evolve in the way it has over the last few decades. Here I refer in particular to the torsion the computation is able to make.

  


Solidworks
Comments: I had quite a lot of anticipation and expectation in finally getting to have a go with Solidworks. I was a quite surprised to see an unrefined graphic user intercace, it looked so 'Windows' - very clunk and click. However, in performance terms, it did not take long to see how much control there was over each element of the form-generating process. I was very impressed, although it might work better with a technical geometric approach.

   


Following a demo from our mentor, I could see that Solidworks had an effective and powerful capability to generate a drawing / 3D model. In Solidworks, you can go back and edit changes at every level of the the dimensions, this was my first true experience of parametric design. I therefore decided to choose Solidworks over Rhino and Blender to generate the form for my 3D design assignment.

I had wanted to create a mini waterwheel that could be placed on a spindle, or a biro, to show the power of water. Also, this form could not easily be produced subtractively, due to the angled fins towards the central axis. What I found interesting was that the 3D printer would not have been able to print this form if it used the x-plane as a foundation plane, as it would not have any supporting structure to undertake effective printing paths. By simply turning the object 90 degrees and printing on the end plane, it had all the support structure it needed to 3D print effectivley.

  


Once the form was completed and all 'dead' lines had been trimmed and cut away, solidworks was ready to export a .stl file. This process converts the form into of a mesh triangles. In lower end software application, .stl files may need to undergo a error correction process in order to ensure the file to be printed does not have any holes (3D printing does not succesfully compute open faces). However, in Solidworks, and in particular with the simplicity of the form I had generated, Nettfab error correction software was not necessary.


Below, the same .stl file opened in Rhino, which, after using Solidworks did not appear to have so much control and refinement possibility. 

  


Assignment : Scan an object

Skanect
Below: using Kinect xbox360 to take a continual scan (in series of frames/faces).




Processing the scanned data in Skanect. The file was then exported as an .stl file, which triangluates the form (cover form the traingles).




File (.stl) opened in Nettfab to correct and repair. I checked the 'actions' for my file and no errors were shown, therefore the object was being seen as a watertight form with an inside and an outside (this is critical for the 3D printing file). The form was trimmed along the x plane and ready to be exported (as .stl) for print.


    

  

Conistent mesh covering of triangles indicating 'watertightness'. I found that there were not any ''holes" found by the software. If they are found, they can be repaired under the 'Actions' in the Nettfab software.


3D Printing

The 3D printing machine that was used was the Ultimaker 2.

Changing the filament

The filament was changed to PLA (Poly-Lactic-Acid, a biodegradable polymer, 2.85mm diameter, that has a low melting point and is printable at very high speeds. Manufacturer claim great roundness and consistency). The new filament was placed on the reel and re-fed through to the nozzle.

   


Sending to Print

File (.stl) for the waterwheel was imported into Cura which creates pathways for the 3D print path on the Ultimaker.  The printer was set to print overnight. It was noted that the software is not accurate on times! Ultimaker takes longer than it states.

Note: It was noted that the most important part of a 3D print is the base. If the job does not start well, it's best to abort and re-set. Also, where possible you can choose to have an apparently large solid area printed with a low FILL density, which appears as cross-hatching inside the scanned piece, see below.

Printing from scan (route: Kinect - Skantec - Netfabb - Cura - Ultimaker 3D Printer):
 
        

Defect under chin area shows lack of detail captured during scanning (the neck/jumper detail shows up well, probably due to contrast).

Printing 3D file created in Solidworks (route: Soildworks - Cura - Ultimaker)

Waterwheel: I had decided to leave one side of the design 'open-faced' so that I could see the quality of print inside the structure. I was very impressed with the result. It appeared to be very sharp and consistent, with reasonably flat surfaces (slight ridging). I understand that the printing actually staggers along the X-Y-Z axis; the effect of this can be seen at this resolution and print speed.

 

 
Tolerances

The variation in print on the 2mm thick 'fins' was between 2.06 – 2.20mm

Download larger SWmodel file here

waterwheel2.SLDPRT

test.3dm