If you don’t check out the prelude to this post with all of the design work, a lot of really fancy looking things are about to spawn out of midair! All told, this project wasn’t difficult on the making end. It’s a fairly basic assembly that is just physically large, and I barely had to “make” anything in the usual sense for me (involving lots of turning larger metal chunks into smaller metal chunks).
As I alluded to last post, I actually began running parts on the Ender flock before the design was even done:
This was the first big print job I’d done in a rather long time, and it kind of showed: Having not taken good care of the filament, some of the spools were rather moisture-laden (see the stringing between the parts). The machine was also just off kilter significantly, which was fine when I made some small robot kibbles here and there. These parts, though; especially the 16″ long forks required a dead flat bed.
In fact, running these parts is what prompted me to re-activate the mesh style leveling that all printers worth buying these days have. I turned it off to save time, since these take their sweet leisurely time grabbing 25 points, but on large machines it’s really essential.
The outside visual pieces are all very hollow to minimize weight. They’re really just ~1.5mm thick outer shells supported by gibberish inside. I tend to prefer Gyroid style filing for these tasks, as it does well at very low fill percentages.
The Amazon Return Ender 3v2 has been outfitted with a 0.2mm fine nozzle since a while ago when I was making Stance Stance Revolution parts. Nothing here needed that level of fine detail, but it was more overflow capacity, so I threw some of the smaller parts at it.
I’m making most of the parts in “native color”, so to speak, instead of a generic single color and painting them afterwards. Most of Corin’s saw is solid patches of color divided by part, and not even weird colors at that, so this was easy. Hey, no need to worry about paint scrapes if everything is the same color underneath!
Some of the internal parts that nobody will see, of course, get made in whatever leftover spools I had. This big center piece will be hidden on the faces anyway, and painted around the perimeter.
This piece in particular (I called it “Neck Core”) was so large and central to the forces the finished assembly wiill be seeing that I actually designed ribs and trusses into it, instead of leaving it a large hollow blob. It is still printed very hollow for the most part at 7 percent fill. But the ribs and ridges force the slicing software to route loops and perimeters there, making it very selectively dense. The ribs run between mounting holes and between the inside circle cutout (Where I was originally planning on putting a battery) and the outside edges.
After a whole lot of filament and several days of “scifi noises” coming from the basement, here’s all of the ingredients. I was going five-wide, all hands on deck at one point: Three Enders and two Markforged Mark Twos (those were making the carbon-filled nylon structural parts, like the motor mounts). I ended up remaking only one part, the green P shaped piece, since I previously threw it in with the silver filament.
All of this effort lined up well with the external suppliers: SendCutSend for the laser-cut ABS saw ring and attachment pieces, and CNC Madness for the custom cut carbon fiber skeleton plates. CNCM specialized in routed composites and is patronized by a lot of UAV builders and robot builders alike. They saw action for Stance Stance Revolution as well!
So… I’m not sure how big I was expecting this thing to be, but it was very surprising when I first put the ring pieces together. This happens often; the scale of the predicament I put myself in only becomes obvious once parts begin arriving.
The saw rim pieces get painted a silver metallic shade. All of this action was happening in my Bathroom-turned-welding-room-turned-paint-booth:
Yes, I am a white-collar bachelor living independently, why do you ask?
This downstairs master bathroom in the very back corner of the house is a total disaster. Not only are the toilet and shower swapped, the flooring is held in by Elmer’s glue or something and just pasted directly on top of the concrete, and the drywall isn’t remotely square.
Best of all, under certain very torrential rainfall conditions, it leaks from the bottom corner of the block wall. This whole basement was shittily put back together (presumably, based on some research, after a major flooding event in this area in 2009) and is falling apart. That’s why I have absolutely no qualms about ripping this bathroom apart and destroying it, because I will do so in the future anyway to address the foundation leak and possibly have it renovated into something less stupid.
Pieces being glued together with contact cement. My preference is for contact cement whenever possible, instead of something like CA glue, since it’s flexible.
The big pile of alligator clips and test leads here later got a Hanging Gardens of Tektronix treatment with probe hangers zipped into a column. The rule of the New Robot Trap House is that I only organize that which I either step on, or which falls on me.
The final step before I could assemble the “UFO assembly” was drilling out some holes in the ring bearing. It’s designed to be used as a turntable, so it came with little rubber feet pushed into the holes. I needed the holes to be threaded a different size, so they were drilled out and tapped or countersunk to taste.
The masking tape cover prevented drilling shavings from falling into the bearing track, which would have caused it to seize up or be crunchy.
The UFO assembly is coming together here with the saw ring fully assembled and other parts fresh out of the Painting Bathroom.
Attaching the motor and its spring-loaded mount was quick. This assembly spins very freely, but it’s obvious the ring bearing wasn’t ever supposed to be loaded like this (one point on one side), so it actually behaves differently when vertical vs. horizontal.
I tested a few different voltages to drive the motor with and settled on 3.7v (1 lithium cell). 2S (7.4 volts) was getting a little too quick to pass the sniff test at a convention, and the motor tended to rip a burnout on the ring bearing which isn’t good for the rubber roller’s existence. At 3.7V, it spun rather slowly but the numerous and odd-numbered teeth made it appear terrifyingly fast through a camera, which is what I wanted.
I prototyped making the conical lids by laser cutting some used Stratasys printer build sheets from the lab. I figured one sheet of ABS was as good as any other, right? This was a chance to practice making the seam, which I planned to use ABS cement and a bridging strip on, and also practice how to fixture it.
It’s actually not scientific at all. I cut a strap of 1/2″ wide ABS plastic out of the same sheet, paint everything in terrifying chemicals that soften the plastic, and then buckle the thing into a cone and clamp the outer edge. Steel blocks hold down the rest of the strap, and the ABS cement works its magic over a few hours, fusing the plastics together.
The finished UFO assembly looks suspiciously good from here. The only thing coming out of it is one pair of wires to the drive motor.
Now to take up the entirety of both of my 8 foot wide benches for the integration! The battery holders are for single 18650 cells, wired in parallel for more run time and capacity. They just mount to the inside of the two neck plates. Out of view for most angles you’d take pictures from. And besides, what’s wrong with a bunch fo random wires sticking out of something that already looks like a gore film villain’s murdering appliance?
The on/off switch is a simple momentary pushbutton, embedded in the handle tube near where you’d normally grab it. Push it, motor go. Don’t push it, motor ideally doesn’t go.
Also visible behind that is one of the hub pieces that bridge the UFO assembly to the forks. It’s just a very large hollow spacer with three through-bolt holes and six holes on the edge for the conical covers.
This whole thing comes together very “All At Once” which isn’t my preference, but I also don’t care enough to drill that deep in this design. Mostly this is caused by the wires snaking through all of the parts! The wires will sit in the hollow channels in the outer pieces.
Smaller external details, such as the many cartoony screw heads and buttons, now get glued in.
Here is the business end assembled! I decided, in the end, to leave the lid off one side because it was easy to show the mechanism this way. This ended up being a great decision, because every convention it’s been to has been filled with people asking how it worked!
And here’s the whole finished assembly. The total build time from hitting go on most of the prints to here was about two weeks. All things considered, it was a fun speed-build of a prop that was pretty well scoped. It’s definitely one of MY products: Fine from 5-10 feet away, doesn’t have every detail and many things are mushed around to fit, and contains a secret robot.
Here’s a testing video, taken while some other con crunching was happening:
This thing is VERY top heavy – so much so that I have to warn people before handing it off. I’ve pretty much destined myself to be the pit crew that wrestles it around and keeps it in working order…. which is totally fine since that’s the role I occupied previously many times.
And a final weight on it! 11 pounds doesn’t sound like much, but having the center of gravity on the end of a stick makes it quite unwieldy. I guess this is another upside to having it made with real structure and materials: As of this writing, I’ve personally dropped it twice and have had quite a few near misses with people misjudging how thick their wrists are. It’s also compliant with at least my local conventions’ rules on prop weight and size limits.
Right now, it spends most of it time adorning my fireplace, like those old-timey shotgun or musket racks. Because Zenless is still taking off and growing its fanbase, I actually haven’t found a dedicated Corin cosplayer at the two conventions this thing has been to yet. But that will surely change soon!
…right?!