Hacker “nemgrea” has a dog that doesn’t like to give up his ball when asked. With all of its energy, he decided to take matters into his own hands and built an automated ball thrower. Though training the dog to actually put the ball back into this fixture hasn’t quite happened yet, it’s still fun to watch, and hopefully will one day provide his pooch with “endless” entertainment.
The fixture itself is a mixture of readily-available PVC pipe and 3D-printed components, using a 4″ to 2″ reducer to receive the smaller-than-normal tennis ball. It’s then fed through a 90-degree bend, and finally out a short piece of 2″ PVC pipe. A 3D-printed piece helps hold the launcher at the correct angle, while another printed fixture holds two motors against the exit tubing, which spin up rotors to throw the ball out the launcher.
Control is accomplished via a clever arrangement of discreet components. When the ball enters the launching assembly, it’s stopped from going all the way down by a solenoid, and detected by a simple microswitch. This switch then triggers two timers, releasing the solenoid after 1.5 seconds, allowing the motors time to spin up. The other timer activates the spinning motors, allowing 4 seconds for them to fling the ball out of the lower piece of pipe.
Entertain Your Pup With an Automated Tennis Ball Launcher was originally published in Hackster’s Blog on Medium, where people are continuing the conversation by highlighting and responding to this story.