Tinkercad Robotics for School: Basketball Machine!

Welcome to a new episode of "Tinkercad Robotics for School", where we explore different ways to use Tinkercad in mechanical design. This is a double celebration event: it's 10 years since Tinkercad was launched! Happy Birthday and congratulations to all the Tinkercad Team; and also to us, the Educators, Students and Maker community who uses this tool in their daily life!

(Also in an unrelated note, this is the 30th anniversary of the "Joyride" album by Roxette, my favorite group of all life! If there are fans of Roxette in the Instructables community, please write in the comments.)

Today's project will have two parts:

1. We will create an electric Tinkercad Catapult (mmm... a CADapult?) that shoots marbles. This catapult can be used for different kinds of science/fun related projects.
2. We will apply the catapult for a mini-basketball game!

You can have a lot of fun with your friends or students, challenging each other to see who can score more points, or who can score more in a row. Also, this is a prototype is open for a lot of improvements. What about a self-feeding catapult? Can you create the perfect basketball game, where every shot is a point and returns to the catapult, and goes unlimited until the battery is drained? Please share your improvements in the "I made it" section!

This project explores the use of the following Simple Machines:

• Lever: the spoon of the catapult works as a Class II lever when the cam pushes it against the spring; and becomes a Class III lever when it launches the projectile. Also, there is a little "basket player" who tries to jump to catch the ball. It uses a Class III lever, being the player the load, and the effort is made by a cam mechanism.
• Pulley: the gearbox doesn't only transfer the force to a cam to push the catapult. It also has a pulley connected by a rubber band to another pulley and a cam, to raise the Basket Player.
• Inclined plane: ideally, the 35 degrees inclined basketball court will allow the ball to return to the catapult. Ideally.
• Wedge: the coupling system between the catapult and the basketball court uses two triangular shapes (roof) to hold the catapult in place, using friction.
• Screw: can I count the small screw I am using to keep the basket on the desirable position? Thanks!
• Wheel and axle: if you were OK with the screw, I can also say that the gearbox's axle is transferring force to a cam and a pulley.

As usual, these Tinkercad Robotics projects requires just a few materials, because most of the components will be created by the 3D printer:

• 1 Computer with access to Tinkercad
• 1 3D printer. Material: PLA. I'm using a Creality Ender 3 V2.
• 1 Gearbox "I" shape (like this one)
• 1 Battery holder for 2 AA batteries, with switch (like this one).
• 2 AA Batteries
• 1 rubber band
• 1 spring*
• Marbles or any other small balls from the same size*
• 2 small screws (like the ones you find in toys and electronic devices)
• Zip-ties
• Pliers (for removing support material)
• Scissors (to cut the remaining zip-tie)
• Flat screwdriver (in case you need to separate the pieces.)
• Mini-screwdriver (for the screws)
• Optional: hot glue gun, hot air gun, mounting tape.

*About the spring and the marbles: this project is critically affected by the weight of the marbles and the type of spring you are using. The more rigid your selected spring is, the farthest the projectile will travel, but also, the gear box will "suffer" more to push the catapult. Also, the heavier the marble is, the lesser distance it will travel. You will have to do a lot of trial and mistake, depending if you are using the catapult for long shots, or as a part of the Basketball game.

Well, ready to start? Then... Come on join the Joyride everybody!

As probably some of you already know, I love to reuse objects and designs, and give them a different purpose. In this case, I will reuse a few components from my previous instructable "Evil Zipline Robot". I will need the body (to attach the gearbox and the battery holder), the cam (to transmit force to the catapult's lever), the washers and the cam's little peg (for the pulley system.)

I cut a portion from the cam, so it will load the catapult gradually, and then release it violently to achieve the launching.

Also, I removed the parts from the body that are not useful for this project, to save in material and printing time.

I created the main body of the catapult using boxes from the "Basic Shapes" menu: one big box of 110mm x 100mm x 10mm, and two tall boxes to house the spoon. Nevertheless, this dimensions would be modified during the design.

For the spoon, I used another box, with a 5 degrees inclination. Then I added a half sphere to house the ball. For the hollow part, I used a cylinder and a smaller half sphere. I also used the washers and the peg from the previous step, to create and axle for the spoon.

On the base and under the spoon, I created cylindrical holes to house the spring (the spring in the design is for reference only.)

At the end of the base, I added two "roof" basic shapes. They will act as coupling system to attach the basketball court.

After finishing the catapult, I duplicated the project on Tinkercad, so I could rearrange the parts for printing. Then, I downloaded the SRT and opened them in the slicer.

I used the following parameters:

• Printer: Creality Ender 3 V2
• Slicer: Ultimaker Cura 4.8.0
• Material: PLA
• Printing Temperature: 200°C
• Infill: 20%
• Supports: Yes
• Raft: Yes
• Scale: 105%

IMPORTANT NOTE: All the parts in this instructable are printed with scale 105%. Don't forget this when the time comes to print the Basketball Court.

Following the design, I assembled the catapult: I attached the gearbox to the body, using zipties and a little piece of mounting tape to reduce movement. I attached the cam to the shaft of the gearbox. Also, I installed the spoon and attached the spring between it and the base.

The cables of the battery holder were connected to the gearbox, each wire to each motor pin.

Now let's start with the Basketball Court.

The coupling piece that attaches the catapult to the court, was made using boxes from the "Basic Shapes" menu.

To reach a perfect pressure fit between the catapult and the coupling, I exported the catapult's base as STL, and then imported it with a 102% scale (note: the image shows scale 104%, but it was too loose, so it works better with 102%). I transformed that shape into a hole, and grouped it with a box that would become the base for the coupling.

To attach the court, I added an extra box and created a hole in the middle so the ball can return to the catapult's spoon. Then I created a 150mm x 100mm x 3.8mm box for the court. I raised the court and gave it an inclination (note: the image shows 5 degrees, however, the best inclination for this plane is more or less 35 degrees). I duplicated this inclined plane, transformed it into a hole and grouped it with the top part of the coupling.

Now having the platform for the court, I need to add a support for the other side. Using boxes from the "Basic Shapes" menu, I created a tall pole of 150mm x 10mm x 10mm, with two perpendicular beams: one for the ground, and the other in the middle to keep the platform in place.

On top of the pole, I created a hole box of 10.5mm x 10.5mm side and duplicated it. One of those holes are to allow the pole to go through the platform. The other hole will be use on the next step.

I brought a 20mm x 20mm x 20mm cube from "Basic Shapes" and grouped it with the hole. Then, I created a small cylindrical hole of 2mm diameter, to insert a screw and fix the board to a desirable height.

For the board, I attached another box (as probably you have realized, most of the shapes used in this project are modified boxes from the "Basic Shapes". It's interesting everything that you can create using the most basic of the Tinkercad's shapes.)

From the tab N.8 of the "Shape Generators - All" menu, I brought a "High Resolution..." figure (the one that looks like a funnel). I used it to create the basket.

After launching the ball with the catapult, the idea is to have it back to the spoon. The court's inclined plane is not enough, because the ball may fall from the sides of the platform. So, I created a fence to work as a funnel to direct the ball to the coupling's hole.

I added a workplane over the platform, and then a 5mm tall box to cover all of it (you can try with a 10mm one). Then, I brought a hole box and a hole roof, to create the area where the ball would be allowed to move after the shooting.. Then I grouped the platform with the new box and the holes, to create the lines that will (theoretically) keep the ball inside the limits.

An interesting feature of our basketball court is the jumping adversary trying to stop our ball. To make it move, we have a pulley system.

On the left side of our basketball court (to avoid confusions: the side aligned with the available shaft from our gearbox), I added to 5mm diameter rods: one for the pulley/cam component, and the other to attach the player component.

On the available shaft of the gearbox, I created a pulley using cylinders and a hollow duplicate of the gearbox in the center, to allow a perfect fitting. Then I duplicated that pulley, brought it to the first rod, add a cam and created a 6mm diameter cylindrical hole on that piece. To keep the pulley on place, I added a washer to lock it.

In the available rod, I added a 6 mm diameter cylindrical hole, a solid cylinder (fulcrum) and a box (lever), checking that the box was directly over the cam of the pulley system.

To create the player, I used and modified some shapes from the "Characters" menu of Tinkercad.

To keep the piece on place, I locked it with a washer.

After finishing the Basketball Court, I duplicated the project on Tinkercad, so I could rearrange the parts for printing. I used the same parameters from the Step 3. Don't forget that all the parts in this project are printed with scale 105%.

After printing, I attached the catapult, the coupling, the court platform and the pole, following the design.

I inserted the board on top of the pole, and then I fixed it using a screw. We will need the rubber band for the next step.

I assembled the pulley system following the position of the components in the design. I added the pulley to the gearbox, the pulley/cam component to the first rod of the court, and connected them with the rubber band. Then, I added the adversary. To keep the components in place, I locked them with the washers, being careful that they are not to tight with the mobile components. To analyze how the components interact, you can watch the video.

After printing and attaching the components, I realized it had several issues that could be improved. That always happens when you create a prototype!

• After launching and returning to the catapult, the ball kept arriving to to the fulcrum of the catapult, not to the spoon. To solve this issue, I cut a piece of the residual raft from the printing, to create a flexible way directly to the spoon.
• The ball kept falling outside the spoon: I added two little walls on each side.
• The angle of the inclined plane was to low. To raise the angle from 5 to 35 degrees, I had to use the hot air gun to bend the coupling and the platform, and I added an extra piece in the pole to elevate the angle.

Also, I modified the STL components according to these improvements.

And our Basketball Machine is ready! Test with different kinds of marbles and springs, challenge your friends and students and the most important thing: Have Fun!