The Carousel (THE ARTIST)

Play "Rapture" by "iiO" to see this post.

This one is something that failed again and again and again and again until I had gained everything I have always wanted, and yet I will only bring destruction upon this world.

Revisiting this after two years to write this post, I can't believe this came from my mind. Some of the manufacturing and assembly techniques I used are incredibly well designed for the 2 years old me. 

The now me would be able to do it with no effort, but I can't believe I managed it then.

Now What Did I End Up Making?

THE MOST GLORIOUS OF ALL. The best part of the sub assembly. It's beautiful. The best of the best. 

"Where did you get this designed from? it's so well made!" 

Hello Kindest Sir,

I have designed and manufactured it in the office of Anglo Scientific in the Royal Institution of Great Britain by myself. Yes, right where Michael Faraday made his stuff, he looks up to me. 

Have a nice day,

- roro

"Ahh ces't Rohit" Peacock and Toto with the most disappointed sigh in 2021 in the lab of digital design. I do not forget anything just so you know. 

So, back to the design. This is a carousel, as the name suggests. To be more specific, it’s a carousel of pens—very specialized pens at that. So, of course, the design had to be a little specialized too. It was made to compensate for the lack of space available on the desk and in the workspace of the tiny robot we had. This carousel was used to bring the specific/desired pen to a pre-registered location on the desk where the robot could readily grab the pen.

So How Does It Work?

Oh man, I went to hell for it—to make it work. Failures! So many. But I’ll tell you what, I was on it. Yes, yours truly, "Ahh C’est Rohit."

The carousel is not a complex design; however, the alignments between parts are very difficult to perfect. On top of that, the spring systems were incredibly difficult to calibrate.

To best explain THE CAROUSEL, we will break it into three parts: The Sliding Contraption (T.S.C), The Carousel Body (T.C.B), and The Suction Mechanism (T.S.M).

T.S.C—14 of those are attached to the carousel body rigidly, with equal spaces between them.

T.S.C is itself just a rectangular box with a blob sliding in one direction, constrained by a spring to tension the sliding mechanism against the pen it’s holding stationary.

T.S.M, which is fixed to the body of the carousel, pulls the slider (which is placed in front of it) through, as mentioned, a suction cup powered by a weak DC motor, capable enough to act against the tensioned slider.

Below are the interactive 3D models, assorted by sub-assemblies, which show you somewhat of a sensible picture of what I’m talking about.

Interactive 3D Model of The Whole Assembly

B. The Sliding Contraption

This one, ouff. It is a four-part design. Nothing too complex. The sliding block is made of the main block and four little cylinders on the side of it, which slide on the slot designed inside the body of the sliding contraption itself.

On top of all this, the thing that drives the slider block is a rod that is attached to the end of the block with a big plate for the suction mechanism to grab onto.

The assembly of T.S.C is very interesting. If you look closely, the slider block has a very peculiar slot at the end of it when viewed from the top. That's where the magic is. First, you’ve got to insert the drive shaft into the T.S.C and then engage the block with the peculiar slot. Then, insert all the M3 nuts into the four slots. At this point, the block is in place, ready for the four tiny little cylinders to be attached to the side of the block, which in turn will lock it with the sliding mechanism. Finally, attach the spring to one of the many holes in the front of the body and then to one of the tiny cylinders, which has a bolt head jutting out.

For the spring mechanism, focus on the two bolts that have washers on them. You'll get it.

The block also has a rubber lining on it, the red-brown stuff. 

The body has the names of the pens directly printed on it and then painted black by me. Some of them are empty because they were custom made, and I won’t tell you the names. So, let it slide.

Below are the four different parts of T.S.C in the 3D view for better understanding.

Interactive 3D Models of T.S.C.

C. The Carousel Body

Nothing much here. Basically, a three-part design in which a stepper motor (Nema 17) drives the main plate.

The main plate is attached to a small drive shaft, which is directly connected to the motor. The main body is bulky and has rubber lining to keep it stable. The main plate holds the 14 T.S.C. with the help of two bolts.

Below are the four different parts in 3D to help develop understanding.

Interactive 3D Models Of The Carousel Body

D. The Suction Mechanism 

This one's not easy to explain. AHHHHHHH. I don’t want to, in fact. Not happening.

So, not writing this after a long time btw. Here we go.

The robot that we had, not saying which one, so suck it, shipped with a suction box, which was basically a pump with a tube attached to it to hold tiny objects using the arm. I kind of reverse-engineered it to fit my stuff.

Basically, I designed a little mechanism powered by a regular TowerPro Mg996R. This servo is hooked to ahahahahahah something really good to make the rod move forward. I’m not even going to explain. It's too much work.

Ok, fine. The drive mechanism in question is a spiral slot on a tube, which, when rotated, makes a straight-slotted cylinder move forward, constrained to the main body. Yeah, probably way too much for a non-mechanical designer to read. Just see the models I will mention later.

The rod, which goes back and forth, is constrained to the body using two bushings to stay in place. The best thing I used my "make do" mind for was wrapping aluminum tape around a clean 3D-printed part to ensure the bushing slides smoothly.

Besides that, the tube with the spiral gear (very similar to the Pen Grabbing Mechanism Vice) is constrained to the body using a big bushing with an aluminum tape wrapped around it. 

Oh yeah the whole T.S.M is connected to T.C.B via a specialized connector that you can find in the whole system assembly pictures and models. It's stuck using the NANO tape I love so much. 

The T.S.M's body is a two-part design. Back then, I didn't have the exact plan of where to place the suction box. I was initially going to place it under the table or at the side with some tape. However, that would have made it a non-modular design, and we wouldn't have been able to move the whole system around.

So, in order to test the whole mechanism and not wait to plan where to keep it, I first printed the whole working part of the body to test it, which was successful. I later decided to put the suction machine under the mechanism body directly. This way, it was a whole unit by itself. It also allowed me to print the other part of the body with custom height modifications to match the height of the drive shafts.

Below are the different parts used to make this work in 3D to make sure you don't understand it even further. I wasnt about to generate all 10 3D files, render and make them perfect for you here, so here's an exploded view only. 

Interactive Exploded 3D View Of T.S.M.

Pens

Well, I don’t have some fantastic CAD models of 14 different pens to show here. It’s too much work designing stuff like that, even for me. I have two of them. So here’s those two.

Go find the rest of them yourself. The names of those pens are in the sliders in the carousel, except for the custom-made ones.

These pens are kind of special. They aren't symetrical at a point but at only in one axis. They can draw various different patterns just by changing the inclination of strike both in Z axis and X (Depending on what you consider X could be Y but not both necessarily). Just look at the model below, maybe it will make sense. 

Interactive 3D Models Of Some Pens

Design and Manufacturing?

Ok, So I designed all of this. How did I end up manufacturing it?

Did I manufacture all of them before even designing them? Yes. Here's how...

This is a big story on its own.

Here we go, So all the things you see are designed to be 3D printed. Meaning all the designs are optimized in the Z axis. They are all flat or shaped in a sweep with the long side linear to the Z axis.

But why? You can 3D print almost any shape these days? Nah, not my designs, will never. I maximize the smooth surfaces. Basically, a cylinder in an FDM bed has all three sides smooth (least rate of error). However, in a square or a pyramid, there's a horrendous warp in the sides, which makes it unreliable in the time of part alignment and extremely unaesthetic.

Look closely at my designs, and you will start noticing the FDM optimization. Also, they look good because they are simple shapes. Humans usually don't like complex shapes, and to process a complex 3D shape requires extended focus, which most of us are incapable of, in turn making it unappealing.

So how come I use so many bolts in most of my designs? Well, first love, and second, again surface smoothing parallel to the Z axis. If I were to print complex one-part designs without fasteners, first it lacks character; it’s a 3D printed part, end of story. You add bolts, and now real modularity and complex assembly techniques get developed, which in turn yield parts like T.S.C.

T.S.C is the pinnacle of my peculiar design development process. Fasteners also teach you advanced pin joints and how to develop rigidity between blocks. It also makes you think about alignment between blocks all the time. It is a shame people avoid fasteners in their designs as much as possible because they end up losing key self-teaching moments.

The best designs are with the least amount of parts? Yeah, that’s something told by the assembly operators. Don’t come with that propaganda here.

Thus, I never designed these parts primarily according to their functionality. I designed them to be manufactured in a very certain way that would maximize the smooth surfaces. All these designs maximize the open mechanism systems as well, meaning every single part that moves is visible.

So yeah, the designs were manufactured in my head first and then conceived. If something doesn’t get manufactured with maximum surface smoothing according to FDM in my thought process, I would not even include that functionality.

Coming back to the actual manufacturing. Henry bought me a gigantic printer. I used it for 3 months to churn out parts. The main body of the carousel took 4 days of non-stop printing and was 1.2 kgs of plastic ahahahaha. I wanted to make it as bulky as possible. It was the only one-part design but the most successful one.

The 3D printer was quite useful. It broke down too often though due to the humidity of then London weather, and it was incredibly hot due to the Spanish winds that year as well.

Electronics

Nothing much. An ESP32, A stepper motor (NEMA 17), A stepper driver(TB6600) with a 12V buck attached to it. That't it. Running on magic basically. 

Software

s e c r e t  s t u f f

A. The Whole System

Yeah it probably works, I guess.

Au Revoir la - lalalalalala - lalalalalala - la 

The system is somewhere in UK right now. 

I have some videos of it working but I am not interested in uploading it here. Lets say it's a concept that's inside somewhere in the chaos that my head has. In this one I definitely went overboard with the amount of fasteners. There's more than 100 bolts. 100 nuts and 70 washers. 

IT HAS BOLTS IN IT. A LOT OF THEM.

: "Its a piece of art, Rohit"

Roland : Thanks for saying that Henry

So well, oh well.

good contraptions, good life. 

[I don't like engineering for a matter of fact. I just do it because it's inside my head so much. It's not going away.]

- Made in Studio de Roro, France and Office of Faraday, R.I, United Kingdom by RolandThsive

Have a nice day,

- Rohit

A Beautiful Picture of My System Assembly