I was taking inventory of my VEX robot creations the other day and realized that I’ve done a very poor job of documenting their existence, let alone their capabilities. I’ve got enough built and still running to fill a couple months of weekly posts. If I extend the scope to my co-workers, and the rest of the web I should be able to keep this up indefinitely.
First up is Spatulabot, my lastest "working" robot. He (yes, all my robots are male) started out as an idea after I’d looked at the rules for the VEX Elevation game. One line in the rules caught my eye, and that was: "Cubes and bonus cubes that leave the playing field are considered out of play." This started me working toward a purely defensive and completely impractical bot.
When I started designing the robot I knew we were designing some high strength gears, but had to get by with the normal gears. It didn’t take me long to exceed the capabilities of the gears and I shredded more than a few teeth. Waiting on the high strength gears seemed the right thing to do so I shelved the spatulabot for a while. Soon after we got the first production run of gears I went to work redesigning the throwing mechanism to increase its power and rate of fire.
It also uses a prototype VEX Power Expander. It takes power from an extra battery to drive the motors, allowing higher current, or longer run time. I’m using 4 motors to run the catapult. The middle gear has some of its teeth sanded off. The remaining teeth allow the arm to be rotated to the ground level, stretching the latex tubing. When the missing teeth reach the large gear it lets go and whatever is in the spatula flies off with impressive speed.
Final performance is a fire rate of about once every 6 seconds and it can toss the 3" foam cubes about 20 feet. HEXBUGs travel a good 40 to 50 feet. The stress of firing is taking its toll on the parts and I’ve had to use some locktight and superglue to keep things from rattling loose. Planned enhancements include adding an accelerometer to the arm so I can automate the arming of the spatula and track acceleration of the projectile. Some sort of feed assist to help get the cubes on the spatula, but I haven’t quite figured out how yet.
I’ll have this bot at VEX Worlds in Dallas in a week and a half, and plan to bring it to the GeekDad booth at Maker Faire next month. I hope to see you there!
Check out a very short video of the spatula in action after the jump.