Designing a Drivetrain

This article is a work in progress

The performance of any drivetrain is based not only on the type selected, but also on the quality with which it is designed and built. These Vex Forum threads on Designing a Quality Drive and Designing Another Quality Drive are great resources for newer teams interested in maximizing their drive's performance.

Design Considerations

Planning: Set constraints for the drivetrain to best accomplish the tasks in the game (i.e. "The width must be less than 13 inches." or "There must be at least 6 inches of room on the front of the drive to attach a mechanism). By setting these constraints before designing, the processes to follow will be much easier to accomplish.
Designing: CAD tools such as those found here are especially helpful when designing a drivetrain, as they allow the visualization of the drive in its final form. However, a pen and some graph paper is always acceptable alternative. Whatever the method, fully designing the drivetrain before beginning the build is very beneficial. Making sure to account for all spacing and planning is crucial to a successful design.
Robustness: Making sure that the drivetrain follows the mechanics listed in the Best Practices article allows for a sturdy start to the robot. Assuring that a base will withstand competition as well as other loads that come with designing a robot. Robustness includes both a lack of wear and bending over time, as well as excessive wear to each individual component(wheels, motors, bearings, etc.)
Efficiency: Ensure that each wheel assembly (and gear or chain assembly, if your drive utilizes these) has as little friction as possible. A good rule of thumb is that if a mechanism can spin freely for more than 5 revolutions, it has minimal friction. Of course, you are the judge of whether or not your mechanisms cause friction, and how much this affects your build. Some common causes of unwanted friction include misalignment (components are not in line, causing rotation to be more difficult) and rubbing (two components are moving against each other; they should be spaced apart).

Simple Drivetrain Designer (if you don't have CAD)

https://www.desmos.com/calculator/ekm1fwjp1y

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Last updated 4 months ago

Design Considerations

Planning: Set constraints for the drivetrain to best accomplish the tasks in the game (i.e. "The width must be less than 13 inches." or "There must be at least 6 inches of room on the front of the drive to attach a mechanism). By setting these constraints before designing, the processes to follow will be much easier to accomplish.

Designing: CAD tools such as those found here are especially helpful when designing a drivetrain, as they allow the visualization of the drive in its final form. However, a pen and some graph paper is always acceptable alternative. Whatever the method, fully designing the drivetrain before beginning the build is very beneficial. Making sure to account for all spacing and planning is crucial to a successful design.

Robustness: Making sure that the drivetrain follows the mechanics listed in the Best Practices article allows for a sturdy start to the robot. Assuring that a base will withstand competition as well as other loads that come with designing a robot. Robustness includes both a lack of wear and bending over time, as well as excessive wear to each individual component(wheels, motors, bearings, etc.)

Efficiency: Ensure that each wheel assembly (and gear or chain assembly, if your drive utilizes these) has as little friction as possible. A good rule of thumb is that if a mechanism can spin freely for more than 5 revolutions, it has minimal friction. Of course, you are the judge of whether or not your mechanisms cause friction, and how much this affects your build. Some common causes of unwanted friction include misalignment (components are not in line, causing rotation to be more difficult) and rubbing (two components are moving against each other; they should be spaced apart).