By: Jonathan Guercio
Introduction:
The holiday season is a fantastic time for getting creative! This year I wanted to make something fun while also showcasing the amazing power and capabilities of our HP Multi-Jet Fusion 3D printer. This printer can produce extremely complex geometries without the need for supports, capture fine details, and manufacture parts from durable PA-12 Nylon material. It looks like I have a fun challenge ahead—and I hope to make this a Tempus 3D tradition in the future!
The Inspiration:
Sometimes the most striking effects come from the simplest designs! Of course, that’s easier said than done. One trick I’ve learned when designing is that it’s always better to start simple and then add complexity layer by layer (pun intended). This approach helps keep the project scope manageable and prevents over-design. So, how simple should we start? The Tree Bauble—a simple, recognizable, traditional shape!
MJF Benefits:
The key objective for our holiday project was to take full advantage of our HP MJF printer’s capabilities. A simple ball would have been no challenge at all! To start, let’s identify the key strengths of Multi-Jet Fusion printing.
No Supports Needed
More common forms of 3D printing—such as FDM or resin-based printing—usually require supports. Since additive manufacturing is performed layer by layer and cannot print in empty space, supports act like scaffolding to hold overhangs in place until the print is completed. With Multi-Jet Fusion printers, however, a full layer of powder is deposited on every layer. The machine then fuses only what it needs, leaving the unfused powder in place to act as a support. After printing, the unfused powder is removed and reused! This process enables the creation of intricate, tight geometries that would otherwise be impossible—and as a bonus, there are no support artifacts to clean up.
Strength
Our in-house HP PA-12 Nylon is incredibly robust. As a key differentiator, MJF printing delivers consistently strong parts along all axes. While other 3D printing methods may suffer from weak inter-layer adhesion that can lead to breakage, the uniform strength of MJF-printed parts opens up surprising possibilities—such as showcasing uncommonly thin features.
Dimensional Accuracy and Detail
MJF printing offers exceptional dimensional accuracy combined with a high level of detail. It truly stands at the forefront when it comes to merging strength with fine detail in on-spec real working parts.
Adding Complexity Doesn’t Add Cost
While increased complexity can sometimes make printing and post-processing more challenging, it generally doesn’t matter with 3D printing. This technology is renowned for creating forms that other manufacturing methods simply cannot, and when combined with the no-supports-needed advantage mentioned above, the design possibilities are virtually limitless!
Adding Complexity:
Given the strengths of MJF, let’s develop a plan to implement them! My idea was to start with a simple sphere and place the Tempus 3D logo right in the middle—a feat difficult to achieve with any other manufacturing technique. I began with a 2D sketch of the basic shape. Since the design is a hollow sphere, I decided that using a 2D profile with the revolve tool would be the easiest way to achieve the desired shape. In this case, I decided to put almost all the features into a single sketch, you’ll see why later.
I opted for a 3-inch diameter with a slim 2.75mm thickness for the outer profile. You can also see the logo plaque here. Note that I didn’t constrain the plaque size because I wanted the flexibility to adjust it later in the modelling process. After adding a simple top hanger, it was time for the first 3D operation!
The first operation was straightforward: creating the outer hollow sphere. I used the revolve tool by selecting half of the outer profile and rotating it about the central axis.
Now that we have our sphere, it’s time to get creative! I started by creating a new sketch a few millimeters from the surface using an offset plane. This sketch defines the intricate “ribs” of the bauble. But rather than drawing the ribs directly, I sketched the areas to be removed, leaving the ribs behind.
As you can see, the blue lines indicate that the sketch is unconstrained. This was intentional, as an unconstrained sketch allowed me to adjust the lines until I achieved the desired look. I continued playing with these lines throughout the process, making it easy to perfect the design.
Once I was close to the desired shape, I used the extrude tool to cut the design out of the sphere.
Now that I had a single cut, how could I transform it into the intricate final shape? This is where the magic happens—the circular pattern tool! I selected “Feature” as the Object Type, which allowed me to pattern the extruded cut (highlighted at the bottom of the screen). Next, I chose the axis around which to pattern the feature and experimented with the number of repetitions, eventually settling on 20.
The result is quite dramatic, despite the simplicity of the procedure!
The Center:
Now that we have our bauble, it’s time to add the logo plate and hanger loop. Fortunately, the necessary sketch was already prepared. Let’s start with the logo plate. I used a symmetrical extrude to ensure that the plate remained centered on the bauble. To add our logo, I imported a vector outline of our Tempus 3D logo, created a new sketch on the plate, and positioned it appropriately before performing a simple extrude. In this case, I extruded 1mm to make it easier to see through the ribs.
Next is the hanger loop—a simple square with carefully considered dimensions. Again, I used the symmetrical extrusion tool to ensure it was perfectly centered.
Finishing Touches: Fillets
Why dedicate a separate step to adding fillets? There’s a common saying: “The fillet tool is the most expensive tool in CAD.” This isn’t because it’s difficult to use, but because each additional fillet can increase production costs—whether through extra CNC machining time or by complicating injection molds. Fortunately, this ties directly into the fourth benefit of MJF mentioned above. In our case, adding fillets has no impact on the printability of the bauble. So, feel free to fillet away!
I hope you enjoyed this write-up, and that some of you are inspired to try CAD if you haven’t already. This was a fun little in-house project!