Prototypes

A major decision I had to make was how exactly the balls would be launched. I discovered online that most of the mass-market devices employ a catapult mechanism within my targeted price range, likely due to the high launch angle. Although I would have wished to use a similar mechanism, the more mechanically simple route of using flywheels was an obvious choice for someone like myself who was concerned on reliability and price. This prototype was a great learning experience when it came to budget engineering, as well as conduct that would prevent future mishaps. In the original design, I modeled around November of 2023, there existed 3D printed parts much more prevalent than the final prototype, such as the ramp that led to the shooting mechanism. I did not fully comprehend the price of parts of such size until I used online 3D-printing services and returned to prices for the piece being around over 30% of the total expected budget if used. Instead, I used wood for this ramp; I should have known that using 3D-printed parts altogether for this project would be very inefficient for the budget target I was expecting to meet (around 80 dollars). This added cost led me to compensate in other aspects that I should not have, including the flywheels made out of wooden poles, or a previous motor I bought that was too slow to launch the ball. Overall, although the dimensions of the device were perfect and the device technically worked, the launching was extremely loud and did not launch far for a motor running at 6000 rpm. More tuning was needed for the project to be a competitive device.

The second prototype was smaller in scope and took around a week to finish. It was meant to finalize the launching mechanism for the production Dog Ball Launcher, as well as replace pieces in the original prototype for cheaper yet more reliable alternatives. With a change from a dual-wheel to a single-wheel launching design, the flywheel was able to be mounted directly onto the motor, removing the gears, bearings, and shaft of the first prototype. Because of this, I was able to afford to use a more high-end wheel type for a flywheel (in this case a 100mm diameter scooter wheel) that could provide more grip to the ball. I also calculated the compression I was looking for on the tennis ball to launch it farther, using some online research, as well as a caliper. Compared to the previous prototype, the ball was able to launch much further than the previous design! The removal of the gears also led to the device becoming much quieter, now at a state where its volume should not scare any dogs away.