When is a COTS part no longer COTS

I really like this definition, although you would also have to define “standard pit tooling”. I would assume this means hand tools and non-CNC tabletop machines that can be carried by one person (e.g. mini bandsaw, drill press, mini lathe)? Assuming it excludes CNC’ed / 3d printed parts, I think it does a good job of restricting what needs to be restricted while allowing things that meet what I think is the underlying intent of the rule (e.g. robot parts are built after kickoff).

This would also clean up other random exceptions that have been added to the rules over the years, like “motors are COTS even if you crimp connectors on them / cut the wires shorter”, “batteries are COTS even if they have terminals attached”, etc.

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While I am certainly speaking from the view point of a team with decent manpower and resources, I don’t think the actual physical fabrication of a part is the time consuming factor during the length of a build season. The strategizing, designing, prototyping, and iterating is what consumes the decent amount of a season.

If your goal was to simply reuse a design from a previous year, the current rules would only set you back a few days to re-fabricate everything exactly as it is. As an example, our actual build/machining team is about 7-10 kids. After we were “done” with the practice bot, replicating everything and building the comp bot took less then 3ish days (“done” is relative, we’re are always iterating).

Additionally, personally we would never reuse parts from a previous year’s robot on the competition robot in a new year. These bots are barely holding together by the end of a long season/off-season, I wouldn’t want to deal with maintaining already damaged/used parts.

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It also allows for an inspector to challenge a team, if a part was reused. Supply the team with the original COTS component, and have them fabricate the part. If they can’t do it in an hour, don’t let them compete until the offending part is removed or a duplicate is fabricated.

Reasonable interpretation would say no water jet cutting, no large CNC, no laser cutting, no plasma cutting.

How is the inspector supposed to be able to get the original part? Do we have to wait for it to be shipped out from the manufacturer, and arrive after the event is over? Who pays for it? What happens after they’ve modified it?


Speaking from the view point of a team that has traditionally struggled with manpower and resources, fabrication is a significant bottleneck.

But at what cost? I think this thread originated from someone wanting to reuse lightly modified COTS components in subsequent years, presumably due to cost. Does not matter how quickly you can manufacture and assemble a robot if you can’t afford it. Though again, I don’t think the discussions started over wanting to save time by reusing parts.

I agree that it’s wise to not reuse components that have already been through a competition season as brutal as the FRC season can be. But not all teams have the luxury of purchasing all new parts every year.


I would imagine there would be a discussion with HQ, and that part of the rule wouldn’t be used flippantly. The burden could also be placed on the team to supply a spare of any exotic part. FIRST could budget ~ max part cost per every 30 teams at an event.
After they’ve modified it, it would be displayed in a trophy case at FIRST HQ.

Thereby scuttling the most likely use of this proposed rule. Now you have to buy a spare you don’t plan to use in order to use the existing part you didn’t have enough money to repurchase. Also, back a step or two, what if the COTS part is no longer available? While I like the standard, the “challenge” doesn’t seem practical.

Added: a likely unintended but serendipitous side effect of the “one hour of pit time criterion” would be that essentially any basic components which could be made in the pit in an hour from stock or COTS parts could be pre-manufactured. This would include many gussets, handmade cables, pre-assembly of gearboxes, tread cut and pre-drilled to fit a wheel, or a handful of solenoid valves installed on a manifold.


Then maybe the inspectors settle for thorough documentation of the part, so the team can detail all the changes they’ve made and how they could modify another.

Have you ever been in a pit at a district event? Nobody is going to waste an hour of their students, tools, or pit space on some absurd machining challenge to prove their part is COTS. Teams have far more important things to be doing with those scarce resources.

Further still, that challenge doesn’t prove anything. Even if it’s a modified COTS component, the inspector has no idea when it was modified. Modified COTS components are perfectly legal, so long as the fabrication happened during build season. All this does it continue the current honor system that’s in place.


The team would do the challenge if the part was critical and that was the one thing preventing them from completing inspection.
The challenge would also make the rule enforceable and less open to interpretation.

You’re right though, for the most part it’s the honor system.

Replying in my nonofficial capacity of veteran RI and absent specific guidance from the event LRI. Random holes in a wheel made before kickoff that are unused in the current final form fits the exception for modification of a COTS device. You are still supposed to fully disassemble the wheel to its component parts. Other people (RIs included) may feel differently. So there is a risk with relying on this interpretation. With the limited time available for inspection, I rarely go this deep. Regardless teams are honor bound to follow the construction rules.


It’s interesting to see that this thread seems to generally be leaning towards “re-use is illegal” for parts that were fabricated in a previous year but the specific fabrications are not used in a following year. I posted a similar concern in the Fabricated parts re-use thread from May and the responses then seemed to generally lean towards “re-use is okay” for these same parts, and included anecdotes such as teams creatively reusing aluminum tubes and brackets and inspectors verifying it.

That this many FIRSTers can disagree on the interpretation of this rule shows a clear problem with its wording. I hope FIRST can clarify it, though I also hope they would do so in a way helpful to team sustainability instead of the strict interpretation they could choose.

(I happen to fall into Nate and Jon’s camp on interpretation. Our low resource team has reused numerous components to save costs while making sure to make new cuts and holes to avoid reuse of old fabrication, and I’ve seen numerous teams do the same thing as an RI. I of course can’t provide an official interpretation though.)

I think this is somewhat a function of summer CD, but even more so that we are a bit farther away from the realities of both the 2019 and 2020 seasons. I’ll admit straight up that during build season within my team, I would interpret the pre-fabrication limitations pretty literally and harshly when the intent was to reduce the amount of effort/labor required, but would look for “loopholes” when the intent was to reduce material cost. On the other side, I was always striving to NOT disqualify pieces for next year. This delayed 3946’s transition to the Victor SPX and Talon SRX because, as the rules were written their first year or two, adding connectors made them unusable in future years, whereas motor controllers with screw terminals could be used year after year.

The rules about not using fabricated parts from before the build season is to stop teams from reusing their chassis and mechanisms such as elevators year after year giving them an advantage of not having to spend the Cad, fabrication and assembly time. Not oh no there is a hole in this price that won’t show up in the final product

My corollary to @Brandon_Holley’s first bullet is:

  • If you can’t return a COTS item back to the vendor because it has been altered in any way from its “boxed” condition, you can’t re-use it, with the exception of the Blue box condition stated and defended plentifully in this thread.

My two bits…

Grease? Anderson connectors? Wear and tear?

I’m not sure our robot had a single cots part that could be in good enough condition to return save for some of the electronics.

Grease? Grease can be cleaned off. We generally do so when dismantling gear boxes, for example, to inspect for damage that will make the part useless for the next season

Anderson connectors? We have made a practice to cut them off and throw them away after a season because we have encountered connectors that had cracked during competition or contacts that had been compromised. New build season = new connectors all around for us.

Wear and tear? Wear and tear is not a modification made to a part, IMHO.

I agree. But these are all reasons why you can’t return a part, but shouldn’t prohibit you from reusing the part the next year.


I like the idea to kill the gray by eliminating the rule:

  • Low resource teams may have an advantage to have robots that do not fail as much mechanically by saving time
  • High resource teams keep the advantage to manufacture new parts that are better customized towards that year’s game

I know that in bowling tournaments there is a handicap score to help new bowlers out… I think reused parts is similar to that. I would like to see more teams devote more time towards a “design” competition and see them play out the way they were intended, where the competition is more on that than on implementation. (also finishing early may give more effort for coding, vision, and AI too)

One more thing, there is an internal dilemma about design that I haven’t figured out yet where eliminating this rule could help me determine the outcome. That is modular design, where you make parts reusable. In software it’s a no-brainer to make code expandable and modular, but mechanically this isn’t always the answer. I think a low resource team could try to go in this direction and discover… they just are not fast enough or limited… consider the “lego” robot, it cannot be as streamlined as a sheet metal customized one … or can it? I still do not know the answer to this, probably a separate discussion, but to get rid of this rule… may have some interesting consequence for that regard.

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