3D Printing

Please find our group assignment here

This is not a new topic for me, but I can’t say it’s my safe space as well. I know some basics of how to 3D print an object, as well as its common advantages and disadvantages, but have not really deep dived into all its features or pushing the ceiling of its capabilities. So this week, I am curious about what kind of ‘design characteristic or typology’ that best utilize the 3D printing capabilities and things to consider when we design for 3d-printed objects.

Key Concept

3D printing, also known as additive manufacturing, is a process of fabricating three-dimensional objects from digital design by extruding material layer by layer. This additive manufacturing process possesses many advantages, like:

• offering design flexibility, which allows us to design complex geometries and intricate details
• allowing highly customized design, like literally you can model (almost) anything for 3d printed objects!
• ability to access the internal structural configurations, allowing us to control the strength, density, or bendability of the object for cost vs performance efficiency
• reduced material waste compared to substractive manufacturing process

However there are still some notable drawbacks, such as a significantly longer production time and how it’s highly dependent on the the filament availability and condition, which currently not as affordable and easily accessible in Indonesia.

Looking at these pros and cons, 3D printing would be more suitable for a low-volume rapid prototyping, especially of a highly-customized and/or complex design objects.

Designing for 3D Printing

One of the challenge of this week is to design an object that can’t be made substractively. Basically, it is all about leveraging on the advantages and uniqueness of 3D printing process. Here’s some design strategies that came to my mind when thinking on how to leverage the 3D printing process:

• Complex geometries, e.g organic or abstract forms, has intricate lattice structures, and/or internal channels/cavities
• 3D operative design keywords, e.g nesting, interlocking, intertwining, twisting objects
• Print-in-place mechanical parts or joints, by combining multiple components in a single print, e.g living-hinges, snap-fit features, ball-joints, etc
• Minimal support design for less waste, by thinking how the design would be printed, maybe less ‘flying’ parts, or something that is printed flat ‘initally’ but can be turned into 3d configurations later
• Considering design constraints/rules, such as clearance value, overhang angle, bridging, etc

If you ask me what I genuinely wanted to make for this week, I actually really want to explore the complex geometries design route, especially in terms of creating organic forms and exploring metamaterials design. There’s this designer that I’m highly inspired of and have been wanting to create designs like her for a while, Laura Maria Gonzalez. So yeah, initially, I plan to take this week as a personal challenge to continue learning blender and explore all these things.

But then, because during the group assignment, we kinda have this ‘special case’ with our 4-5 years old PLA filament, which assumed to have absorbed moisture a lot due to PLA hygroscopic nature, resulting in a lot of stringing, porous, kinda rough printing result, I think it’s not really a smart idea to print something with lattices or cavities structure, that have the potential to yield a lot of stringings considering our filament situation.

Besides, my instructor also reminded us for the first-spiral development and how this week should be an easy week! -which serves as a wake-up call for me. Therefore, going back to the first spiral and thinking of how this week could help my FP development, I decided to focus on designing for the ‘print-in-place’ mechanism by considering our 3D printer design constraints/rules.

I then specified to this design criteria in mind,

• ‘Fit mechanism’ connection with high flexibility of movement, considering clearance value
• ‘nested’ in some way –> containing nested components, so that the interior components need to be printed in place and can’t be taken out
• designed to be laid flat on the printing bed, but then later can be configured into a 3D form
• prototype with simple & clean shape, if works well, then can try to customize/incorporate organic design

Was thinking of something like rubik’s cube, but nah that’s too complex. Lets do something less heroic! I finally took inspiration from the fidget spinner toy.

3D Modeling Fidget Spinner

The fidget spinner that I will design will have no bearing but utilize gyro-sphere shape. The fact that it has ‘rounded angles’ can serve as an invisible boundary that will prevent the internal wheels to slip out / taken out. Basically, what I need to do is to make a series of nested outer wall perimeter by offsetting it inside accounting for the clearance.

1. Sketch: Setting the overall object dimension

   Define the overall object size, which is max. 30 mm

   

   Sketch the ‘sphere’ body wall. At first, I do this by first drawing a circle curve and then trim it with a square. But in the end, I only need one side of curve, because I’ll revolve it around. Also, set the height to 15 mm.

   

   ❗ It’s really important to maintain the rounded angle curve, because in the end, this angled wall is the one that will hold the inside nested components in place. So, if you want to make the wall height shorter, keep in mind to maintain the roundedness or think of other sorts of ‘brake’ mechanism

2. Setting Parameters

   Next, we have to set some parameters for simultenaeous change when we need to update one part of the design. In this case, the variables that need to be governed are the wall thickness and the clearance for the joint.

   • wallThickness = 3mm

     

   • clearance = 0.25mm

     

     Based on our 3D printing characterization , the range for the clearance is betwen 1.5mm (snug fit) to 3mm(looser fit). I think the 2.5mm fit is good enough for the spinner, because I also takig into consideration the ‘stringing’ effect potentials.

3. Making the perimeter wall body

   By using the Revolve tool, make a wall surface based on the rounded curve we’ve made before

   

   Then, using the Thicken tool, add wall thickness to the surface, don’t forget to input the value we have set before.

   

   Now, one ring is done! What we need to do next is basically offsetting the wall inside, several times.

4. Giving rooms for Clearance

   Offset the inside wall surface by inserting the clearance value we’ve set before.

   

   This surface will serve as the base for us to thicken the next interior wall.

   

   Repeat these steps several times until we reach the core of the spinner And it looks like this.

   

5. Adjusting for 3D printing

   Next, we need to evaluate whether this design is already suitable to be 3D printed or not. To do it, we can use the view section tool.

   

   Here, I just realize that by ‘offsetting’ the sphere wall, it will make the inner walls to be gradually descending to the centre, which will cause the design to need supports in the centre area when being 3D printed. Besides, the walls’ edges are also too pointy. So, I will make some adjustments by cutting the most outer wall edges to be flat, by using the extrude-intersect tool.

   

   To accomodate for a smoother spinning, I fillet all the wall edges with fillet radius of 0.4mm

   

6. 3D Design Result

   

   And here’s the result! Not really going as planned because it ended up needing supports, which I tried to avoid initially. But for the first spiral, this is good enough (I think).

Slicing

Now that the design model is done, export it to 3MF / STL and then import the file to the slicer software of your choice. Here, we’re using the Prusa Slicer.

Once you load your file, as you can see here you can adjust the extrusion quality, the type of filament you use, supports, infill, and even you can adjust the parameteres of each part even more.

Because my design has the floating part towards the centre, so I need to enable support on the plate.

If you’re done with your settings, you can go click ‘Slice now’. The software then will start slicing your model.

As the slicing process is done, you can see, simulate, and evaluate how the machine will go printing it. You can also learn the estimated printing time and the amount of filament used for your object.

If all is well, you can click ‘Export G-Code’ to send your file to the 3D printer.

Printing

Following the steps and procedure mentioned in the group assignment page, we can go ahead print. Due to our filament issue, I tried to dry our PLA filament in a longer time, approximately 9 hours prior to printing this object.

✨ Don’t forget to glue your bed prior to the printing and while the bed is in the pre-heating process, to ensure that the first layer fully stick to the bed.

🖍️ Monitor the 3d printing process especially on the first layer, after that you can just monitor from time to time. In my case, I didn’t really pay attention when printing the first layer, turns out there’s a trouble with the machine’s Y-axis and I didn’t realize it. But thankfully, Eka noticed it and abort the process immediately.

Fresh from the oven!✨

Surprisingly very little stringings!🥳

Post-Processing

Next, remove all the excess stringings, as well as the printed support. At first, all the parts will got stuck together, so sometimes you have to give a little bit of force, to remove the excess. I used pliers and mini files to help clean it. You can also finish it further by sanding the surface.

The resulting waste and the product

Results

Test Result 1

• Unexpectedly smooth result!😲🥳
• I think because we dried our PLA even further, the latest one before my test, I dried it for approximately 9 hours- so, the resulting filament came out very neat which results in the bigger, loose but smooth, clearance. Before, in our group test, the 0.25 mm clearance felt like a good fit to me, considering I also want to avoid the parts to be stucked together due to the stringing issue. While this is such an amzing the fidget spinner, but I kinda want to make it tighter a bit more, because I could not held the parts in place if I wanted them too stop at certain angle. So I think, on the next test I’ll set the clearance to 0.2!
• I made the wall thickness to 3 mm, but looking at the result, I think 2 mm would works just fine, and might result in a more sleek design
• I found the wall height a bit too tall and enclosing. I think I want to make it shorter, so that we can really see the inside wheels
• Now that the spiral 1 is done, I want to add some personalization to the shape to make it more interesting.

Test Result 2

Reflections

To design objects specifically for additive manufacturing involves leveraging the unique capabilities of 3D printing to create geometries that are not feasible or practical with subtractive methods. If I can summarize, here are my notes on some design strategies to consider when designing objects that can’t be made subtractively, enhancing the 3D printing capabilities:

• Design complex geometries
• Designing parts with minimal support requirements, if possible
• Combine multiple components into a single, integrated part that can be printed as a single piece

• Design parts with the the 3D printing design rules / constraints in mind

Design Files

Fidget Spinner (Onshape)