TrikeBot - VEX Robotics Chassis

thingiverse

Chassis for a one motor, one servo, three-wheeled, remote controlled vehicle using VEX EDR components. I would only suggest printing version two. Version one is only included for insight into my design process. This project was my first attempt to completely replace VEX metal structural components with 3D printed plastic. I was teaching myself how to use SketchUp Make. In order to make it a manageable project, timewise, I chose to focus on using a single motor for acceleration, and a single servo for steering. For control, I chose to use a no-brainer with an older-style controller. Version one featured an enclosed chamber for the battery, and had the steering wheel at a perpendicular angle. It functioned, but steering was quite difficult and shaky. After a little research on motorcycle steering wheel physics, I learned about rake, and added a third piece between the impulse and steering portions to add an angle to improve steering. After a little testing, I decided to also shift the weight of the battery forward. It also seemed useful to add a gear between the servo and the steering wheel to help center it while it's in its resting state and to allow the distance of the wheel from the steering section to be adjustable. So I wound up creating a version two of both the impulse and steering sections. Print Settings Printer Brand: MakerBot Printer: MakerBot Replicator (5th Generation) Rafts: Yes Supports: Yes Resolution: High Infill: Default Notes: Don't print the version one pieces unless you're curious about my design process. The version two pieces make for a much better driving experience. Print impulse sections, or the version one steering section, flat along the top. The version two steering section is designed to be printed flat along one side. The rake section intended to be added between the version one pieces doesn't have a great printing angle; I told MakerWare to "flatten" it for me. Post-Printing Needed parts. Parts 1 VEX 75MHz Signal Splitter (AKA 'no brainer') with its accompanying mounting screws and nuts. A couple of metal stand-offs and a rubber link to wrap the antenna around. 1 VEX 75MHz Receiver (also, a transmitter if you wanna control it) with its accompanying mounting screws and nuts. 1 VEX 3-wire motor (or 2-wire with a 3-wire motor controller) 1 VEX 3-wire servo. 1 7.2V robot battery with a long-enough twist tie. 6 square shafts;2 2"+ shafts, 2 3"+ shafts, 2 6"+ shafts. 5 36-tooth gears. 15 lock collars. 3 2.75" wheels. 2 black plastic spacers. All VEX EDR parts are available through VEX: http://www.vexrobotics.com/vexedr/products/accessories (well, actually, some of these components have been discontinued; this is probably only interesting to people who have old VEX stuff around.) Assembled the impulse gear assembly. Attached the receiver and signal. Used a little tape to attach the antenna along the stand-offs. Assembled fork with lock collar to fasten it onto the end of a long square shaft. Attach the servo to the signal splitter, and have it on and attached to the receiver with the transmitter on and the joysticks left alone. This will hold the servo centered as you center the wheel and enmesh the gears. Attach the impulse and steering sections using the mounting screws of the signal splitter. Setting up remote control Plug the impulse motor into port 3 on the signal splitter and the steering servo into port 1. Be sure to switch channel 3 to be reversed on your 75MHz transmitter, or you'll need to get used to steering backwards. Completely assembled and running.