Laser Cut Nerf Ball Shooting Lego EV3 Tank

For the final project of my 1A term in Mechatronics Engineering at the University of Waterloo, we created a laser cut tank with the Lego EV3 kit (this was required) that shot Nerf balls.

This instructable is by no means a complete design report. If you would like to read more in to the design, the report as well as more details on the project can be found on my website here:

https://a2delectronics.ca/2019/03/03/laser-cut-nerf-ball-shooting-lego-ev3-tank/

The treads are made out of laser cut 3mm MDF board. Using cutting a flexible pattern in to the wood, we were able to create a fully functioning tread. We attached both ends of the tread using 18AWG wire loops soldered through holes in the ends of the treads. The gears were made from This may not have been the best option for the treads, but it worked fairly well and was easy to do. The treads were not durable in the wet weather outside and one of them broke as it got wet and soggy.

The ball hopper mechanism was inspired by the design of paintball hoppers, and laser cut out of 3mm MDF. It worked very well at slow speeds, and was very repeatable. The top cover is attached with magnets and is removable in order to reload the hopper.

If we were given more time and resources, we would like to have made the balls fire faster and further using compressed air instead of a spring. However, the spring powered solution worked fairly well after some tuning, but would not fire as straight or as far as was originally planned for.

If we were given more time and resources, we would like to have made the balls fire faster and further using compressed air instead of a spring. However, the spring powered solution worked fairly well after some tuning, but would not fire as straight or as far as was originally planned for.
Using the Lego EV3 Robot kit was a requirement for this project, driven by the school, as these kits are easy to debug. If we were given more time and more freedom, we would have used an Arduino based platform instead, as this gives more expandability, power, and features.