New to VEX V5 — What Drivetrain/Chassis Should We Start With?

VEX V5 Robotics Competition V5 Override (26/27)
1

Hi everyone!

I’m new to VEX Robotics, coming from FTC, and I have a few questions about drivetrain design.

I’m currently starting the CAD for our VEX V5 robot, and I’m wondering what kind of chassis/drivetrain you would recommend for a new team.

In FTC, I was used to seeing parallel-plate drivetrains with mecanum wheels, and they seemed to be very common. I know there’s no single “best” drivetrain and that it depends heavily on the game, but I’d love to hear what drivetrain designs are currently considered strong or commonly used in competitive VEX V5.

For this season specifically, what would you recommend as a good starting point for the chassis? For example, would you recommend a 4-wheel, 6-wheel, or another configuration? And what wheel type/size would you go with?

I’d also appreciate some advice on the drivetrain motors and gearing. Should I use the green, red, or blue V5 motor cartridges, and what gear ratio would be a good starting point for a competitive drivetrain?

I’m pretty comfortable with CAD and have experience using both Fusion 360 and Onshape. I also found the official VEX V5 Parts Library for Onshape:

VEX V5 Parts Library – Onshape⁠

Is this the library that most VEX teams use for their CAD, or are there other libraries/resources that you would recommend?

Basically, I want to settle on a solid drivetrain concept first, including the chassis, wheels, motors, and gearing, and then start building the rest of the robot around it in CAD.

Thanks in advance! I really appreciate any advice :folded_hands:

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Welcome to VEX!

There’s a lot of fine print with drivetrains, but I’ll simplify it to get you started quicker.

The tank drive is two parallel drive pods connected with a brace. It excels in pushing power, which is great for midfield this year. The X-drive is four wheel pods angled at 45 degrees each, creating an X pattern. This drive excels in maneuverability, which may help weave through the countless objects in Override, but it forfeits pushing power. The H drive is the same thing as the tank, however it has an extra wheel/motor on the middle brace for strafing. The H-drive is objectively terrible though, so don’t do it. Mecanum is also a variation of drive you can use, but it would take too long to explain and I don’t wanna waste your time with my sub-par explanations so refer here for more! If you go tank drive, consider a six wheel variation. Gives you a bit more push. As for wheel size, I’ve never been picky about it, so hover around 2.75” or a bit bigger and that’ll probably work. As for gearing, I’m gonna refer you over here because unfortunately I’m not qualified enough to discuss that (I haven’t tinkered with ratios yet). CAD is one place I can speak for though. If you don’t know, if you’re in a high school, you can ask them to apply you for a Fusion360 Student License, which grants you a free copy for a year. VEX is a learning experience after all! OnShape is good too, but I will always always recommend Autodesk Inventor or Fusion360. Inventor is a bit more detailed than 360 and that’s what my team uses.

Good luck in Override!

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Welcome to VEX, and the forum!

Here’s a quick overview of different dts: Drivetrains | Purdue SIGBots Wiki

The meta this season, like every other season, is tank drive.

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It’s by far the most common dt design you will see, however this season due to the 55 watt limit on dts, other types of dts have become viable such as the X-drive. A note on using mecanum, it is really rare to see VEX teams use mecanum wheels, my team used them our first year and we weren’t really fast enough to compete with the other teams.

A couple common configurations:

Motor Cartridge Wheel Size Gear Ratio Final RPM
Blue-600RPM 3.25 5:3 360
Blue-600RPM 2.5 4:3 450

Those two are very similar but in my experience they are the most common. Here’s a decent video to get you started.

About CADing: Yes that library is what most people use when CADing on Onshape. You mentioned Fusion, if you’re more comfortable with it here is a library for Fusion: Release 2.0.0 · VEX-CAD/VEX-CAD-Fusion-360-Library · GitHub I’ve never personly used it but I’ve heard good things about it.

Hope this helps! If you have any other questions, let me know.

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a good drivetrain for vex is tank drive cus more pushing power, also 2,25 wheels for this game running at 450 rpm (600 rpm motors running with 36 to 48 tooth gears) maximizes cog and has good torque and speed. 6 wheels is best for distributing weight to make sure that the wheels don’t dig into the carpet making the amount of wattage used higher. that is the library used for vex. dt for this game is best if its 55 wt or 44 wts.

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I think you should start with a 4 motor drivetrain with a mix of 6 Omni and Traction wheels. My team is using 3.25" wheels. Gear ratios for starter drivetrains would most likely be a mix of 36T and 48T, and I would say for your drivetrain to use green or blue cartridges.