This will be me sharing the information I learned during the assembly of the dome panels for BB8. These are my experiences and I hope to convey them as clearly as possible while also providing as much information as I can. Once again, thanks to the BB8 Builders Club for all they have provided.
The topic of this presentation will be assembling the 3 dome panels. It will not deal with anything else. No talk of magnets, electronics, printer settings, finishing/smoothing, painting or any other part of BB8’s noggin. I know that means it’s a limited subject. Worry not. First, I plan to provide more informational pieces as I continue the process. Second, I think this information may be of use to someone out there who may be having trouble translating the printed instructions to action.
This part of the process requires very few tools to complete. I used my CA glue (crazy glue type glue), files, cutters, ruler and a pin vise. I used a black marker to make marks where material needed to be removed for a better fit. I also used freezer paper underneath everything once I started gluing. Parchment paper should also work. My glue was not very thick for this, so it easily ran to the bottom at the joints. I don’t think thicker glue would travel as much, however, it is definitely not worth the risk to the work area. Especially since any lumps of dried on glue may affect getting any future pieces to line up correctly. Or, you could be using the dinner table and the consequences of glue on that are not worth mentioning. Make sure there is nothing that keeps the paper from laying flat. Small pieces of filament, screws, chip or cookie crumbs, the cat, anything. It is very important to get the pieces assembled as flat as possible.
Here are the three pieces set up as they will be assembled. I am using Hatchbox PLA for my construction. I know the manual does not recommend it, but I haven’t had any problems with the parts I have printed. Also, it was the only filament I had handy when I decided to start my project. I filed off the skirts and smoothed down the edges where the panels will connect. That was done to remove a few material lines that would get in the way of a correct fit. I didn’t do any adjusments yet, just a bit of cleanup. Setting the panels up like this not only helps to get an idea of what you are going to deal with, it is also a good feeling getting a glimpse of things coming together. Now is when you should get the pieces as close as they will be at final assembly. This will show you any major trouble spots you may have to deal with. Make sure you use a flat surface when doing this, or any, assembly. Check that all the pieces are sitting flat and line up as close as they can. You may notice some extra material here and there that you missed during part cleanup. This will let you find and correct that before you go any further.
Here you can see that these two pieces are not perfectly aligned as they sit on the table. There are two ways to deal with this. One is to remove material towards the bottom of both pieces and bring them closer together. The other would be to assume the fit is ok, and it will close together at the top as you assemble the parts. The main concern is to keep the bottom of the panels completely flat while keep the tops flat as well. There may be slight misalignments down the side, but those can be addressed during smoothing. It is a good idea to print out the ring for the dome top and use that to check alignment of the top of the panels. I did a little of both. Some slight filing/sanding at the bottoms and adjustments as the pieces were glued together.
Once you get the panels ready to go, check them for fit one last time. You can see in this photo that these panels line up very nicely. I decided to start with these two since they are the least amount of work. I used a 1/16 drill bit to clean out the holes for the “pins” that help join the parts together. I didn’t enlarge the holes at all, since my filament fit snugly into them as printed.
Here is how I set the pins up the first time, before I came up with a better way. (I share that a little later) DO NOT USE ANY GLUE YET! I cut short pieces of filament and stuck them into the holes on one panel. I then pushed them into the opposite hole in the other panel and trimmed them down until they fit. I only pushed one pin into one hole at a time until they were all sized correctly. I then pushed the panels together as they would be assembled and check the alignment and gap. Luckily, I didn’t have any issues there, but I can assume that will not be the case for everyone.
Once I was happy with the fit, I pulled the pins out, put a slight amount of glue on the end of the pin and set them in the holes on one panel. I only placed a little bit of glue on the ends of the pins due to the fact that the fit is snug and the glue will cover the pin and hole as it is installed. If any glue pops up from the surface, just wipe it off with some paper towel while it is still wet. You could file it off once it sets up, but it is much easier cleaning it up now. You can see that the pins are not perfectly flat on the ends that protrude. This is an effect of the cutter I used and also works to guide the pins into the next part. You could enlarge the holes a bit if you have issues with your filament lining up, just make sure everything stays aligned if you do that. You probably want to use the thicker glue to take up the extra area in the holes also. Once the glue on the pins dries, you are ready to assemble the two panels.
I learned that if you cut the filament into pieces just under 1cm, they will fit both sides with no problems. It may be a tiny bit shorter that would actually fit, but you want to leave some room for the adhesive to grab on. I went ahead and cut out the rest of the pieces I would need for the final panel and didn’t have any problems. You should still test fit and make any adjustments before adding the glue. One you have corrected anything that prevents a proper fit, pins too long or short, removing material to get alignments correct, go ahead and glue the pins in.
You can do this any way you chose. Put them all in the last panel, put them in one side of the last panel and the opposite side of the assembled, or like I did, glue the pins into the already assembled panels. I don’t know which way is the best. That is the way I did it. Allow the glue to dry once again, then move on. Installing the last piece is fairly similar to the first one. Add your glue to the pin ends and edges of the panel. Don’t forget the bottom lip as well.
I would like to say I just pushed the final panel in on both sides at once. I did not, it would not cooperate. I installed it on one side, then did the other. The trick was keeping the alignment as close as possible so none of the pins broke during the process. I will say that the first side came out while I was adjusting the second, so keep a watch for that.
Once the pieces are all in place, admire your handiwork and LEAVE IT ALONE. Let everything cure and settle. If you are constantly checking it, you will mess something up. Once enough time has passed, then you can check for any major issues and put it on your head. (you will do that)
This is only the first step. Don’t get too caught up on finishing and making it look pretty. You need the other pieces to do that correctly. You could do a “weld” on the seams now, if you’d like. I will go into these steps in another post. For now, I hope this has provided some insight into this part of the process.