Ri3D (Robot in 3 Days) 2018!

Hello everyone! Teams 26982E ([TVA] Alumination Robotics) and 59990Z (E-lime-n-ators 2) would like to present to you all our Robot in 3 Days project! Of course, I will explain our design choices and whatnot, but be sure to watch the video first!

So this collab took place over the 21st-23rd of June, and took place at 59990Z’s place (We are both private teams).

Our decided design goals were to make a robot that could win qualifiers in our region by focusing on one aspect of the game. We took a lot of prioritizing inspiration after seeing how contested the flags were at SingVex, and decided to make a shooter-based robot. It seemed obvious to both of our teams to make a flywheel for the ball shooting mechanism, especially after seeing how balls kept falling out of the puncher-based robots in the SingVex videos. We also wanted to make some sort of cap flipper to contest the caps on the ground, but decided to come up with a mechanism for flipping those later. We agreed on the motor setup being a 6m HS drive, a 3m Torque flywheel, a 2m intake/indexer, and a 1m cap flipper.

We began the 1st day with making our drive, a simple 35x35 drive with all omnis, so we could be done with that fast and not have to deal with the extra time needed to add tractions in the middle, as they are not the same size as the omnis (4" Tractions != 4" Omnis?? Get on that VEX!), as well as have tons of space to add mechanisms. After the drive was done, we added our intake roller, originally gearing it 2:1 Turbo. We decided to try and add another roller with the same gear ratio right above it to act as the indexer, and it worked quite well. We finished all these things in a very short amount of time, and decided to figure out where to mount the flywheel, which wasn’t very difficult. With the frame in place, we put on the 2.75" wheels, as they were the only ones we could fit on without hitting the indexer. To this flywheel we mounted a 49:1 gearbox (we used this speed to make up for the tiny circumference of the flywheel) and called it a night.

The 2nd day began with some interesting news, we would have a huge hole in the 3rd day where we could not be working on the robot, basically turning day 3 into the reveal shooting day, meaning we had only this day to tune the flywheel, and create a cap flipper. We spent the morning tuning the gearbox and adding the hood, only to be dismayed that at lunch when we tested it, the flywheel was not spinning fast enough to launch the balls high enough. After we ate, we replaced the flywheel’s internal motor gears to HS from Torque. This launched them high enough, but the motors would burn out after 3 shots. We had some important decisions that needed to be made. We could 1: Redo the entire shooter, 2: Take apart the whole gearbox assembly and figure out where the friction was coming from, or 3: Which is the one we chose because of the time constraints, to power the intake and indexer off 1 motor (and gear it for more torque), and add that extra motor to the flywheel. We took a lot of time to do this, and it kind of worked. We still had the stalling issue, but this was solved when one of us saw that the motors driving the flywheel were clearly not spinning even close to their max RPM (Facepalm) So we converted the motors once again back to torque and converted the flywheel to 3.25" for a little extra speed, which thankfully allowed the flywheel to consistently shoot the ball at the height of the high flag. While the flywheel was being worked on, we developed a simple 1 bar cap flipper that had a 90 degree hook on the end to grab onto the grooves in the cap. This worked very well and was geared 2:3 HS via sprockets. We programmed it real quick and had a working robot!

The 3rd day really began at around 6pm, which is when we started to shoot the reveal. However, there was 1 major complication to this. It was 99 degrees out this day in Texas, meaning our flywheel motors were overheated and refused to hit the high flag more than a couple times. Other than that, the rest of the sequences we wanted to do went quite well and finished the day at 9pm.

As neither of us have made a flywheel in VEX before, we know now that friction kills in a very bad way, and will apply this knowledge to our own real competition robots should we choose to use a flywheel.

Also it was totally unintentional that the intake rollers were able to flip caps XD

We hope you enjoy and feel free to ask questions!

The reveal is a lot of fun. :slight_smile:

All in all a good robot. Some quick back of the envelope calculations puts the max linear speed of your flywheel at
69.5 ft/s
and the max linear speed of mine at


To get about the same effective gear ratio with 3.25 inch wheels you could have geared for 35:1 instead of 49:1.

Obviously Ri3D are not designed to be perfect design for the rest of the season the extreme gear ratio just jumped out at me.

I also have a few concerns with the flywheel. As tabor said, it has a fairly extreme gear ratio with less motor power than his, so the acceleration should be fairly slow. Also, you began running the flywheel right before shooting, which means it most likely didn’t get to full speed. I also don’t think it had a ratcheting mech on it, which could lead to motor damage.

@Carter we did make a ratcheting mechanism, however it didn’t quite work. We were going to just slow it down using code, but we did not have enough time to complete program as we were under a strict time limit.