Miniature Mechanical Pinball Arcade Machine

Hello everyone, in this instructable I will show how to design and make a mechanically powered pinball machine. Drawing inspiration from many of the mechanisms used to deliver power to mechanical clocks, I decided to incorporate these mechanisms into a pinball machine to give it an extra layer of life. This entire project was made using mainly 3D printed and laser cut parts so it's easier for others to remake the project if they so wish too. Albeit, the project is composed of many components, so I will try and explain each as much as I can. So without further ado, let's get started on making some clockwork.

Designing and Manufacturing Equipment:

• 3D-Printer (Elegoo Neptune 4 Standard Edition)
• 3D Model Slicer (Prusa Slicer)
• Laser Cutter (Sculpfun iCube 10W)
• Laser Cutting Software (Lightburn)
• Designing Software (Fusion 360)

Handheld Tools:

• Assortment of pliers
• Hammer
• Sandpaper
• Bolt cutters
• Digital Calipers

Materials:

• PLA Filament (Around 0.5kg)
• 3 sheets of 12" x 8" - 3mm Baltic Birch
• 2 sheet of 12" x 12" - 3mm Baltic Birch
• 1 - 70mm Diameter spiral coil
• 1 - 20mm Diameter Helix coil
• Superglue

To get a good grasp of the physical size of a design and to jot down some initial ideas, I typically start off with a physical, life-sized sketch. This helps me gain an understanding of the size of my components so that I can better design parts that are realistically sized in the future.

Here, I will list out some of the design tolerances I used when designing all the parts of the pinball machine. I cannot stress enough how important it is to understand tolerances, especially during the design process. For example, 3D printed parts will always have sockets that print a bit smaller than what you designed in Fusion. It may only be off by about 0.5 mm, and honestly, that seems inconsequential, but that’s all it takes to compromise the connection with its respective plug and, in the worst case, it could even ruin the entire print. Now bear in mind, these tolerances are mainly for the machines I used, so generally, you should do some experimentation with your own to find out its limits. However, this list could serve as a guide.

3D Printing (Elegoo Neptune 4 with PLA):

• Sockets:
• +0.3mm offset for a tight fit with connection
• +0.45mm offset for loose connection
• +0.6mm -- +0.7mm for a free spinning axle
• Threads:
• +0.15mm on either internal or external threads for an idea fit (Fusion automatically gives a 0.1mm offset to the internal threading so this is a 0.25mm offset in total)
• Note: I like putting the offset on internal threading, like the threads inside a nut, so you only need to do the one offset. The external threading can then just be the base value Fusion gives it

Laser Cutting (10W Diode Laser)

• For the most part laser cutting is nearly perfectly accurate so the tolerances depend on the connection
• The wood is labeled as 3.0mm but after measuring with digital calipers the actual thickness was 3.3mm. That is the value I used for all my designs
• Laser Cut Plug - Laser Cut Socket
• Perfect connection
• 3D Printed Plug - Laser Cut Socket
• Perfect connection
• Laser Cut Plug - 3D Printed Socket
• +0.3mm offset
• If possible, measure the 3D printed part first then laser cut for the most accurate results

Prior to this project, I had only ever used Solidworks, so it took a little time to make the transition to using Fusion 360. Though some of the functions are fundamentally the same, there are a couple of neat things I learned about Fusion 360 along the way that I thought I'd share, just to make design on Fusion 360 a much smoother experience. Overall, (now don't go telling Solidworks this) but I really did enjoy using Fusion 360 a lot more. Not only were the controls much more user-friendly, but all the functions just seemed so much more convenient to use, making the entire design process very quick and simple. Anyway, here is a short list of what I discovered.

Making Assemblies:

For Solidworks, the process of design goes as follows: you make a multitude of parts and then you slap them into an assembly that is a separate file. Fusion 360 is, well, a "fusion" between the two; instead of making them separately, you can conveniently make them in the same space. The problem was, I decided to follow my previous methodology and made the mistake of designing by adding new components each time. This was a terrible mistake as it made my entire design process a logistical nightmare; I had to flip through each and every component and open their individual subtrees, just to perform some basic modifications. So I learned, always design using bodies. It keeps everything under one tree, and bodies can be manipulated by a larger range of modification functions as opposed to components.

Combine Bodies:

This function is absolutely amazing for designing connections as it allows you to automatically make the cut without having to mess around with sketches and projections. This saves a lot of time, especially if you plan on designing your own connections.

Gear Generator:

Though I suppose its use is more niche than the other functions, having a tool to generate relatively standardized gear sizes makes it far simpler than actually designing the gears yourself. The tool was also very convenient to use and absolutely saved a lot of time in the design process.

Thread Generator:

This was absolutely my favorite function of this entire project. Instead of using store-bought screws, I decided it would be fun to just 3D print bolts and nuts. Having the thread generator made this design process all the better, as Fusion can automatically model the threads based on the size of the hole or shaft.

Press Pull:

Remember all the tolerances I mentioned beforehand? Well, with this tool, modifying the sizes of parts to fit their tolerances has never been easier. Simply click on the face you wish to offset, type in the value, and immediately you have made the change without the need to make a whole new sketch or extrusion.

So let's start off with what I think is the most interesting part of this entire project, the tourbillon mechanism. This will act as the mechanical heart of the arcade machine, and its purpose is to just give the pinball machine some movement and aesthetic without the need for electronics. Though it might seem complicated at first glance, in the next few sections I will explain the components the best I can so that anyone can honestly try and make their own rendition.

What is a tourbillon then? Well, the simplest way to look at it is to imagine a Grandfather clock. The clock operates using an escapement mechanism, the swinging pendulum arm. As the arm oscillates back and forth, it allows energy to slowly 'escape' from the system which in turn powers the clock and gives it its signature ticking sound. A tourbillon is basically a really fancy version of a pendulum arm, but instead of using gravity, it uses the forces of a spring to maintain its oscillating motion. Moreover, this mechanism is more complicated than a swinging pendulum, but it can be designed to be much more compact, hence why I chose it.

I will explain the way I designed this tourbillon in 3 steps:

1. Base
2. Platform
3. Escapement Mechanism

(The Black/Gold parts are 3D printed, while the wood-colored parts are laser cut)

Let's analyze each photo as it goes from left to right.

In the first photo, we have 4 unique parts: the wooden frame at the bottom, the large winding gear that houses the spring in the middle, 4 brackets at the ends, and a shaft that connects our spring to the platform above.

The Wooden Frame: The reasoning behind the use of wood in this case is not only to ease production time, as printing such a frame would take a long time, but also to ensure that the connections are perfect without the need for glue. If you take a glance at the triangles on the brackets, you'll notice that these triangles are on both the top and the bottom, and they perfectly slot into the wooden frame.

The Winding Gear: This is the powerhouse of the entire system. I made an open-bottom design with a handle for easy winding of the spring. The gear is only connected to the external end of the spring, not the center shaft.

The Brackets: These are very important pieces as they not only hold the gear in place but also ensure it spins in only one direction. Taking a closer look, you can see these little flaps that extend out into the spurs of the gear. These flaps are printed thin enough to flex and allow the gear to be spun in the direction the flaps are pointing, but if spun in the opposite direction, they will stop the gear. This is how the spring is wound up.

The Central Shaft: This piece will be connected to the center of the spring and supported by a metal rod in the center. Bear in mind, this piece should not be connected to the rotational motion of the winding gear.

The second photo has an example model of a spring placed in, just as a reference for where the spring should go. The spring I used was a metal spiral spring like the one modeled. A metal spring can store significantly more energy than a plastic one, so I decided to use it for this project to make the mechanism last longer. Though it would be possible to 3D print a spring if desired.

Adding onto the previous assembly, we have affixed a central gear ring. This is the axis on which our platform will rotate, and the gears are necessary to allow the entire mechanism to function. Finally, we attach the platform to the assembly. It will be connected to the central shaft, which will in turn rotate the entire platform that will soon house the escapement mechanism. The escapement mechanism, in turn, slows down the rotational speed of the platform.

Please bear with me on the strange coloring; in real life, it will be entirely black because of the filament I am using, but for the sake of demonstration, I have colored each of the parts to make it easier to distinguish each component. Also, note that the wood-colored parts are the only ones that are made using laser cutting; the rest are 3D printed.

In the video, I will thoroughly explain how the mechanism operates and demonstrate how to fully assemble the tourbillon.

Alright, now let's move on to how the frame of the arcade machine was built. To start off, my one limitation was laser cutting. I only have a very small laser cutter that can, at most, only cut a 130mm by 130mm square, which is about as large as the diameter of the tourbillon gear ring. The board of the pinball machine was quite literally just the size of the board that I ordered. I had to deliberately position it inside the laser cutter to get it to cut the holes in the board. The exterior panels are segmented into individual pieces that are connected together using 3D printed frames and bolts. Obviously, if you have access to a larger laser cutter, I would not recommend my frame design as it takes a long time to 3D print all those frames, but I do really like the industrial-like aesthetic of the box. Oh, and of course, the theme behind my pinball machine is battling aliens, so the tourbillon has a spaceship cover, and I also laser-cut some extra pieces to go along with it. The theme reminded me of Space Invaders, so I made my own parody of that name.

As I previously mentioned, I lacked the ability to laser cut larger pieces of board, so instead of relying on laser-cut connections, I decided to design a frame that can be 3D printed to hold all the wooden panels in place. Each bracket piece has some bolts protruding out the side; the side panels can be fitted onto these bolts, then mounted on with a nut to keep them in place. Once the frame is fully assembled, the smooth slot cutout can then hold up the main board of the pinball machine. Finally, in the last image, instead of starting off the design with my desired 10-degree angle, I had to start with the main board perfectly flat. This really helped to make the initial designing a lot easier, just remember to account for the angle adjustments to the brackets at the front and back ends.

The main board is just the base 12" x 8" piece of 3mm Baltic Birch. Thankfully, since the dimensions on both the Fusion 360 piece and the physical piece were the same size, I was able to measure out the locations of the holes on the real piece. Afterwards, I made a sketch of the front face of the board, saved it as a DXF file, and sent it to my laser cutting software. Of course, the entire cut didn't fit onto the cutting surface, but I was able to make the smaller cuts inside the board. So, looking at the last image, which is of my laser cutting software, I can determine the proper dimensions of that cut using the DXF file. All I had to do was ensure the laser (the red square) was in a known position on the program, pointing at the same spot where I wanted that cut on the board, and then make the cut.

(Once again, the colors are to distinguish each individual part; they are all 3D printed.)

For the paddles, I wanted them to automatically reset to their starting position without having to manually pull the paddle back. This design also gives the paddle far more acceleration and generally provides a much more tactile feel when you press it. The way it operates is by having yet another thinly 3D printed part that acts like a spring. Once you release the button, the spring will automatically push the paddle back into position. Also, the two triangles on top of the red piece are the connection between the mechanism and the board; they slot in perfectly, and the friction holds them in tightly without the need for glue.

The design of the launcher was relatively simple; just modify one of the bracket pieces to have a tube that would fit a spring. The spring would be held in by the plunger once the handle has been tightly screwed onto the end. The spring I used was a metal coil spring with an 18mm diameter

Designing the outer panels was of no difficulty, thanks to the menagerie of tools that Fusion 360 provides. I simply designed one large panel that would house the main board and gave it a 10-degree angle. Afterwards, using the Combine feature, I cut out the holes for the bolts and the square connection pattern. Then, finally, I used some offsets and mid-planes along with the split bodies features to cut them up into the pieces that I could laser cut.

The final pieces to discuss are the guiding piece of which they simply serve to guide the ball back into the launcher or guide the reward pellets into the reward box. The way I planned to have this machine be played is that I would have tiny pellets placed on the alien spaceships with the aim being that you knock off the pellets with the ball. The ball will return to the launcher but the pellets will be collected into the box as the guiding piece will filter out the tinier pellets. Also as you might have noticed in the back, there is rather large frame to hold the tourbillon. It mounts onto the side panels and holds the tourbillon just high enough on the main board.

The final pieces to discuss are the guiding pieces, which simply serve to guide the ball back into the launcher or direct the reward pellets into the reward box. The way I planned for this machine to be played is that I would have tiny pellets placed on the alien spaceships, with the aim being that you knock off the pellets with the ball. The ball will return to the launcher, but the pellets will be collected into the box as the guiding piece will filter out the tinier pellets. Also, as you might have noticed in the back, there is a rather large frame to hold the tourbillon. It mounts onto the side panels and holds the tourbillon just high enough on the main board.