R2-D2 Part 10: Top Ring
The top ring was one of the simplest parts of my full-size 3D printed R2-D2 build. Six straightforward prints, a perfect fit using custom locating pins, and a look ahead at whether to fit a 450 mm Lazy Susan before starting the dome.
Compared to some of the previous sections of the build, the top ring felt almost like a reward. After dealing with complicated assemblies, supports, alignment issues and countless test fits on earlier parts, this was one of the simplest sections I had printed so far.
The top ring is made up of six individual pieces, all of which print flat on the build plate. Wanting to keep everything as flat as possible, I added a brim around each part before printing. Although the parts weren't especially large, using a brim gives me that little extra confidence that the corners won't lift during a long print. In the end, every single piece printed perfectly with no lifting, no warping, and no failed prints.
As always, before reaching for the glue, I dry fitted everything together. This has become one of the most important habits throughout this entire R2-D2 build. It's much easier to discover a problem before the glue is applied than after everything has permanently bonded together.
When I placed the completed ring onto the top of the body, it initially appeared to be just a little too small. At first I wondered whether I'd made a mistake somewhere, but after looking more closely at the design, I realised this may have been intentional. The ring includes several through holes designed for bolts or locating pins, allowing it to be pulled securely into position.
Rather than trying to clamp the ring while gluing, I decided to make use of those holes. I designed and printed a set of simple locating pins that fitted neatly through the openings.
Once inserted, they pulled the ring into perfect alignment with the rest of the body and held everything firmly in place while the glue cured. It turned out to be a very straightforward solution and made the assembly process much easier than I expected.
With the pins in place and everything lined up correctly, the top ring fitted beautifully. There were no gaps to worry about, no awkward adjustments, and no surprises waiting for me once the glue had set.
There's honestly not a great deal more to say about this stage of the build, and that's actually a good thing. After several parts that required careful planning and problem-solving, it's nice to have a section that simply goes together exactly as intended.
I'll leave the rest to the photographs, which show the completed top ring fitted to the body and ready for the next stage of the R2-D2 build.
What's Next?
The next decision is one I've been debating with myself for a while.
Although the top ring is now complete, it isn't actually glued to the main body. The reason for that is the next stage of the build. Between the body and the dome sits a 450 mm Lazy Susan bearing, allowing the head to rotate smoothly just like the real R2-D2.
I've been weighing up whether to simply buy one or try to print my own.
A ready-made 450 mm Lazy Susan costs around £25, which isn't unreasonable considering the size, but the engineer in me always likes to see if there's a way to print something instead of buying it. I've found a few printable designs online, but they all require loose ball bearings to be assembled. I haven't yet found a completely printable design that I'd trust to support the weight of the finished dome over the long term.
The other option is not to fit one at all. Quite a few builders simply place the dome on top of the body without any form of bearing. Since my R2-D2 won't be motorised or fitted with electronics, the head doesn't actually need to rotate. It would simply sit in place, which is perfectly adequate for a static display.
Before making a final decision, though, I think I'll print the lower ring of the dome first. That will let me see exactly how everything fits together and how much clearance there is before I decide whether the Lazy Susan is really worth fitting. It seems far more sensible to make that decision once I have the parts in front of me rather than buying a bearing now and hoping it's the right choice.
For now, the top ring is complete, and the main body is another step closer to finally meeting R2-D2's dome.