VEXU Robot Rules

Everyone has probably seen the VEXU rules by now

Lets go through the changes that I noticed.

  • After years of terribly confusing and vague rules on what is a “raw stock” VEXU now has some common sense rules.

    There is a secondary list of what doesn’t count as “raw stock” in the context of VEXU that might otherwise be considered “raw stock” in other contexts

    Limiting teams to traditional rigid construction materials like metal or plastic for robot structure and VEX/VEX Pro for off the shelf motion components.

  • Now VEX Link is legal in VEXU, a silly oversight for several years. Given the state of VEX AI VEX Link has been a dead technology since @jpearman made it work.

    VUR10 Each Robot must utilize exactly one (1) V5 Robot Brain and up to two (2) V5 Robot Radios connected to a V5 Controller.
    a. Teams must abide by the power rules noted in and .
    b. Wireless communication between Robots is permitted if using legal V5 Robot Brains / Robot Radios.
    No other types of wireless communication protocols (e.g., radio, Bluetooth, Wi-Fi) are permitted.

  • The manufacturing rules given “raw stock” had 1 notable change from last year. VUR3 (d) was removed. (old rules listed below)

    VUR3 Fabricated Parts may be made using the following processes:
    a. Adding material, such as 3D printing.
    b. Removing material, such as cutting, drilling, or machining.
    c. Bending material, such as sheet metal breaking or thermoforming.
    d. Casting or molding material, such as injection molding or sand casting.
    e. Attaching materials to one another, such as welding or chemically bonding (e.g., epoxy)

  • The custom electronics for sensing and processing rules were left unchanged.

  • The pneumatics rules were left unchanged.

  • The 2 robot sizes were reverted from 18" cube + 15" cube back to 24" cube + 15" cube.

  • The rules on what is considered a fastener were expanded upon to include epoxy. Given epoxy was already a legal fabrication method I think this just makes it legal to use with off the shelf VEX components.

    VUR9 Teams may use commercially available fastener hardware on their Robot. Examples include
    (but are not limited to):
    • Screws, nuts, rivets
    • Hinges, pins, rod ends, threaded rods, hose clamps
    • Bushings, radial bearings, linear slides
    • Spacers, washers, standoffs
    a. To be considered a legal “fastener” in the context of this rule, the primary function of the part must be to join or fasten together two otherwise legal parts. For example, a prefabricated non-VEX
    wheel (which would be illegal under ) would not be considered a “fastener,” even though it
    may also technically serve the purpose of bridging the connection between tread and a shaft.
    b. Adhesives such as epoxy, glue, or tape are considered “fasteners” for the purposes of this rule, provided that their primary function is to fasten together two otherwise legal parts. For example, using grip tape to improve wheel traction would not be legal.

Also I think its worth saying the polish on the VEXU manual has gone up. Look at some examples of equivalent rules from last year and this year in main manual and VEXU appendix.
Spin up (top), Over Under (bottom)

Spin up (top), Over Under (bottom)

The rest of the manual has these short rule descriptions to communicate quickly what a rule is going to be about. You can see the VRC starting volume rule hasn’t changed since last year and neither has the way its presented. Now however the VEXU manual has gotten a lot more readable to match the rest of the manual.
@VEX_GDC I bet you didn’t think someone would notice, but I noticed.


One more notable change:
VUR6c was added to ban the use of fiberglass, acrylic, and carbon fiber as they are now suddenly considered “excessive safety hazards”.

Fabricated Parts may not be made from Raw Stock which poses a safety or damage risk to
the event, other Teams, or Field Elements. Examples of prohibited materials include, but are not limited
a. Any material intended to produce flames or pyrotechnic effects.
b. Any material that is liquid at the time of the Match. Examples include hydraulic fluids, oils,
greases, liquid mercury, and tire sealant.
i. This does not include fabrication processes that involve the use of liquids, such as milling
coolant or epoxy.
c. Any matter that shatters or otherwise presents an excessive field/safety hazard upon failure.
Examples include fiberglass, acrylic, and carbon fiber sheet/tube stock.
i. This rule refers specifically to material legality itself. Any potentially unsafe mechanisms
made from legal Raw Stock may still be addressed by and .

This is unfortunate because Carbon Fiber and similar composites have been legal for the last 5 seasons, since Turning Point. I know many teams have invested a significant amount of money into carbon fiber materials, so to have that investment made unusable suddenly is quite painful.


Upon request, I edited the OP to fix some formatting


I’m still back on VR5, but this reads more like a “forgotten thought”. I think the rule is accurate, and the Example poor. Referring to “carbon fiber” not good, because chemically, it is only carbon to carbon. It ignores all the other polymers that are now coming online with equivalent tinsel strength. Spiderwire VERY useful, but with very specific shear strengths. it is a UHMWPE, with more than Carbon. But basic molecular force gives it the strength and electrical property. Inspectors will have no chance of differentiating Spiderwire from carbon fiber. Then there’s “Graphine”, which are essentially carbon fiber that forms as a nanotubes. It can take the shape of a sponge, and is as resilient, conductive and black.
So I agree with the rule, but take caution on the Examples as being all inclusive. No shattering (more specifically splintering; remember, safety glass shatters, but doesn’t splinter).

@PaulW , Could you clarify what you’re trying to solve/the question you’re trying to ask here? Your post is a bit hard to follow.


I was struck by the dialog around carbon fiber. That is such a poor example, as most of the world is composed of chains of carbon, as atoms or molecules. (I gave examples of each).
I think the rule would be better served if aligned to the incident. Something like “any accident with slivers/shards breaking off (or being exposed) on the robot with 50:1 ratio width/length will be a major violation”. Then we can argue about the ratio, but the rule is all about safety, and examples for that are seldom necessary.

Today you learned it’s hard to write rules.

I think the parts of VUR6 (the rule I think you’re actually referring to…) that read

Examples of prohibited materials include, but are not limited to:

Examples include fiberglass, acrylic, and carbon fiber sheet/tube stock.

Help to imply that examples include Carbon Fiber, but may not be limited to Carbon Fiber, and that the rule applies to similar materials that can easily be deemed unsafe for use for the reasons you state.

However, we must remember that because a material contains carbon, it doesn’t immediately make it Carbon Fiber. I imagine the intent here was to govern the use of interwoven bits of carbon bonded together with an epoxy/resin of sorts, and not to govern the use of something like steel alloys that contain carbon. I don’t believe spiderwire can shatter or splinter, and would imagine as long as it fits within the other rules, may be legal for use.

Its also important to remember that G3 exists too. This helps to alleviate some of the greyer areas that are inevitable. For example:

If a component’s legality cannot be easily / intuitively discerned by the Robot rules as written, then Teams should expect additional scrutiny during inspection.

For your splintering example, how would you recommend that be measured? Do you expect the referees/robot inspectors to put themselves in harms way to measure out a splinter to determine if it’s large enough for the violation you mention? I don’t know if you’ve ever received a splinter from carbon fiber, but I have. And they’re NOT fun.

Can you elaborate by what you mean when you say:

the rule is all about safety, and examples for that are seldom necessary.


I’ve also worked with carbon fiber sheets, and just handling can create splinter risks.
What does a referee do? Judge. As such, it is his conclusion there is a major violation (measures not necessary at the time).
My vote is get rid of the example. At a minimum, Capitalize the first letters (i.e., Carbon Fiber).
Good overview of “Carbon Fiber” at: Fabrication and Properties of Carbon Fibers - PMC. The article states Carbon Fiber must have 92-99% (by weight) carbon. How would you suggest referees measure this? And I believe this is without the resin it reinforces…

it is his conclusion there is a major violation (measures not necessary at the time)

Its easier to make a judgment call on carbon fiber splintering on the field if it never sees the field in the first place.

The article states Carbon Fiber must have 92-99% (by weight) carbon. How would you suggest referees measure this? And I believe this is without the resin it reinforces…

I would tell the referee to reference G3 and use common sense to work with the team to develop a common understanding that “If it looks like carbon fiber, feels like carbon fiber, smells like carbon fiber, performs like carbon fiber, its probably carbon fiber.”

My vote is get rid of the example .

Why, though? Is carbon fiber not a material that exhibits pretty obvious splintering and shattering risks?

Im still confused, though,

Are you advocating that carbon fiber should be made legal, or remain illegal?


I have edited the OP’s original post to fix a slight error.

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FINAL POST: You don’t find Carbon Fiber itself. It is a reinforcing agent that adds tremendous tinsel strength and lightness to a polymer. Where used (and the thickness of the epoxy sheet) will significantly impact the potential of splintering. For these reasons, I’d vote to PERMIT epoxy coated Carbon Fiber (in any form), and leave it to the Teams to BUILD to prevent splintering. It becomes a design choice, knowing a potential exists for a major violation for “splintering/slivers” if poorly designed.
Remember, steel or aluminum burrs that break off and lodge in the skin (a “sliver”) are equally dangerous. And the B2 bomber doesn’t splinter: Carbon fiber Composites -- Adding magic wings to airplanes - Material Introduction

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I appreciate our conversation and your insight and perspective.

But I think we will end up agreeing to disagree on some of the opinions you have stated regarding carbon fiber.


Perhaps the main confusion is coming from terminology. In my industry (fabricating air cleaning and wastewater treatment equipment) we refer to the materials in question as FRP (“Fiber Reinforced Polymers”) then go on to describe what the particular fiber and matrix is, for example carbon fiber reinforced epoxy.

In the game manual, there is a reference to “Fiberglass” as well, which is a colloquialism (usually) for Glass Fiber Reinforced Polyester, although sometimes Epoxy is used at the matrix.

While not as egregious a technical problem as referring to air cylinders as “pistons” (which, thankfully, does not appear in any VEX documentation) there is still confusion to be had by using common terminology rather than industry-standard terminology within a specification. There is still minor terminology issues (although it is better since R18 was reworded) with students using the term “plexiglass” to refer to “any clear plastic,” and example of a similar issue to the confusion PaulW is discussing.


Does the restriction of Carbon Fiber also affect the use of Carbon Fiber Nylon, or any other Carbon Fiber infused filament for 3D printing? The purpose of the rule is for the safety of competitors and volunteers. The Carbon Fibers in the filament are small and would not pose a splintering problem, in the case of a part breaking.

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have a question, can i use an another microcontroller in the competition VEX U, and other sensor, exaple: MCU6050 for controlling the angles of my robot.

Sorry by my grammatic.

Please refer to the game manual for the official rules. Appendix C give the VEX-U rules: VRC Over Under Game Manual - VEX Robotics Specifically, please review rule VUR-12 for additional electronics.