First-time Vex V5 Competitor Needs Help: Upgrading Drivetrain for Maximum Performance!

[SuhJae]

Hello! This is my first time participating in the Vex V5 robotics competition as a solo team. For the past two months, I have been building the Hero Bots and learning the basics of robotics. I feel prepared to make my first robot by myself. Below is a picture of the drivetrain that I have built.

However, I have found some problems:

1. The motors block the area where I plan to place the intake device for Triball.
2. The drivetrain needs to be faster. Initially, I used a direct drive with 200 RPM motors for the above configuration. I attempted to speed things up by using a 60-tooth drive gear and a 36-tooth driven gear—which is overdriven—but the torque was too weak, and the robot could barely move. (below is the only photo remaining of that drivetrain)

This is the only photo I got (for now)

Could you provide helpful resources or advice on creating a competition-ready drivetrain for this year’s competition?

[AmethystMoon]

Make sure that every shaft goes through at least two bearings. While you will lose a bit of torque with that 60-36 reduction, it shouldn’t be so much that you can’t move, especially with that light of a bot, so I would look for sources of friction - I can’t see your gears too well in the picture, but it looks like the shaft that they’re on only goes through one c-channel, which will lead to a lot of wiggle and misaligned gears possibly making it difficult to move.

[thedudeJose]

@SuhJae

but the torque was too weak, and the robot could barely move

There should be more things wrong than just the gear ratio. That’s 333rpm, and since you have an aluminum chassis weighing around 2lbs (at least in the photo), there must be something seriously wrong regarding the bot itself, not the gearing.

[SuhJae]

The photo below was taken while building the robot, and I have added one more c-channel (3 for each side and 6 total) so the gear does not wiggle.
Also, I said “barely move” since it could go back and forth and rotate, but not diagonally using the mecanum wheel. (when only 2 wheels are active) Even though it could move back and forth, the bot struggled to move at first until it picked up speed. (it did not reach 200 RPM max speed when it did in direct drive.)

[EcstaticPilot]

A mecanum drive is probably not a good idea for a first time team and you will notice that top teams (mostly) always use a tank drive. Some general building tips are don’t use 5 wides for the c channels where the wheels go and instead use 2 wide channels which will help you save a lot of weight. Here’s a good post about designing a drive Designing Another Quality Drive

[turbodog]

The post in the thread below is a good place to start. Can’t have a top-performing bot if it’s 1) falling apart 2) bending 3) suffering from friction… etc.

What makes something good build quality?

First, to specifically answer your question. Good build quality is when the bot operates at the limits of the materials & design NOT the quality of assembly, the motor power is put to use moving stuff not creating friction/heat, and you don’t have to keep fixing stuff that breaks. To achieve that, here are some guidelines. Bearings should be checked to make sure the shaft rotates without friction or feeling ‘notchy’. If you feel notches, the bearing is damaged (usually from overtightening). …

And yeah, drop the 1x5 c channel for some 1x2 or 1x3 (1x3 is easier to use for first time teams).

Mecanum, by its nature, is slower than a normal bot in straight forward speed. If you are going to run mecanum, your driver REALLY needs to drive it differently. If they can fly a quadcopter well (forward, reverse, nose in hover, figure 8, etc, not just out/back) then this is a good starting point for mec wheels.

For a mec bot, you need good balance, otherwise it won’t move properly.