How to Build a Tennis Ball Machine

There’s no denying the best tennis ball machines are quite pricey to buy ready-made. If you’re handy with electronics, you can build your own. In this post, we’ll go through how to do this. Ready to get started?

List of Supplies

In our example, we used components from MakeBlock. Here’s a list of the supplies that we used:

  • 3 x Beam 0824-144
  • 2 x Beam 2424-312
  • 4 x U Bracket-C
  • 4 x Flange Bearing F688ZZ
  • 4 x 125 PU Wheel
  • 4 x Wheel Hub 3
  • 2 x D8x96mm D Shaft
  • 2 x 62T Timing Pulley
  • 4 x 62T Timing Pulley Slice
  • 4 x 4060 Plastic Rivet
  • 4 x 4120 Plastic Rivet
  • 24 x Type 7 GB Socket M4x14C
  • 4 X M5x5 Jbckscrew
  • 2 x 8×1.6 Washer
  • 4 x 0824-320 Beam
  • 4 x Rubber Foot
  • 2 x CNC Motor Case
  • 2 x CNC Motor
  • 24 x Timing Pulley
  • 2 x 56mm D Shaft
  • 4 x 90T Timing Pulley Slice
  • 2 x 4mm Shaft Connector V2.0
  • 14 x M3x-C Jbckscrew
  • 2 x 4x8x3 Flange Bearing
  • 2 x P3 Bracket
  • 1 x 0808-136 Beam
  • 10 x 4mm Shaft Collar
  • 2 x 3×3 Bracket
  • 1 x Acrylic Sheet
  • 2 x 1-direction motor driver
  • 2 x D4x160mm Shaft
  • 2 x 0808-312 Beam
  • 3 x 45° Plate
  • 6 x P1 Bracket
  • 24 x M4x22 Screws – Socket Hexagon Button Head
  • 8 x M4x35 Screws – Socket Hexagon Button Head
  • 28 x M4 Lock Nut
  • 6 x M4x30 Screws – Socket Hexagon Button Head
  • 12 x M4x16 Screws – Socket Hexagon Button Head

Step 1

Create the frame using an L-Shaped configuration.

Step 2

Install two right-angle connectors on the end of the base. You’ll be left with a triangular structure with the point facing forward.

Step 3

When you’re putting together the mainframe, leave the four corner screws alone. You’ll need these to attach the foot pads. Only use lock nuts on the frame because the vibrations that the machine will put out while in use will be powerful.

Step 4

Attach the foot pads to the screws in the corners, and the frame is complete.

Step 5

Now it’s time to put your friction wheel module in place.

Step 6

Now connect everything to the shaft. Tighten the screws.

Step 7

Process the rivets and then attach them to the friction wheel. It’s now time to glue on the timing belt. At this point, you want to leave the headless screw in place but not completely tightened. You’ll do that once you’ve finished with the whole assembly.

Step 8

Repeat with the other module to create the second friction wheel.

Step 9

Now that that’s done get the part you’ll be using in the bracket for the friction wheel ready, and then you can attach the friction wheels to the frame.

Next, after you prepare the part used in friction wheel bracket, you can install the friction wheels. Don’t forget to set the timing belts beforehand. You’ll use the longer belt at the top and the shorter one at the bottom.

Back to the friction wheels, one should be installed at the bottom of the frame so that it’s leading the frame. The other should be placed higher up, with the frame in front of it.

Overall, it should look something like an S-Shape. Make sure that there’s enough space between the two so that a tennis ball can fit.

Step 10

You’re ready to install the motor module now.

Step 11

Start with the synchronous belt wheels.

Step 12

The timing belt wheel can now be installed onto the shaft and linked up to the motor.

Step 13

Follow the same steps with the second motor module.

Step 14

When that’s done, the motors can be attached to the main frame. You’ll need to secure it with the motor brackets. Link the timing belts to the synchronous belt wheel before you screw the motors into place.

Each belt should be attached to a different motor, and the belts must be tight.

Step 15

It’s a good idea to secure the end of your motor output shaft. This step lends extra stability and ensures that it won’t shake loose easily.

Step 16

If necessary, adjust the timing belt’s tension by moving the bearing. It can now be fixed in place.

Step 17

To further stabilize the structure, run two support beams along the sides of the frame. These beams should be attached at an angle so that triangular shapes are formed between the original frames and these beams (get someone to hold the frame steady while you to do this).

Step 18

That concludes the construction of the support structure. Now it’s time to install the circuits. Start by welding the wires for the motor. Use a higher gauge wire and make sure to place a protective tube over the welds so that they don’t short circuit.

Step 19

The boards controlling the motor speed can now be installed. These boards will allow you to control up to a 10A current. For added stability, secure the circuit to some scrap wood or the acrylic board.

Step 20

You can now secure the sheet or scrap wood and the circuit board to the frame. Using the acrylic board is easier here because you just fit it into the threads of the two diagonal support beams that we used to reinforce the frame in Step 17.

Step 21

You’ll then need to splice together your power cord and attach it and the battery. Use a secure T-joint and make sure that the cord is connected to both edges of the circuit board. Check that all the connections between the circuit board and motor board are secure.

Step 22

You’re done. It’s time to test out your creation.

Final Notes

Building a tennis ball machine does require some expertise in electronics, but it’s not impossible. It could be a fun project to do with your kids. Or, if you’re not all that familiar with electronics, perhaps get the kids to lob the ball for you instead.