Ruling on 3D Printed Cable Chain

Hi all,

I’m new to the forums, so apologies if I’m not following some sort of protocol.

I just saw Karthiks ruling on 3D printing cable chain for cable management as shown below:

“This is not permitted in VEX U, unless the 3D printed part were come out of your allowance of as . This would definitely not be permitted in the VRC. Essentially any wire management devices must be commercially available to be legal as per <R7l>. i.e. You can’t just use random materials for a home made cable management solution.”

I have to say I am very disappointed. We are allowed to purchase cable chain in the high school VRC according to the Skyrise rule book as long as its sole purpose is for cable management. If this is the case, what harm is there in allowing 3d printed cable chain? It does not give a team any particular advantage, in fact it would be easier to just buy the stuff, its not expensive. However it is an awesome learning opportunity for the students. I recently got a 3d printer for my classroom and would LOVE for the students to CAD up their own cable chain for their robot. Karthiks ruling makes that a no-go.

I completely understand when rules are made to keep the playing field even, but in this case there is no benefit regarding the competition. It would solely be an awesome LEARNING opportunity that would not affect match play in the slightest.

Having said all of that, I could be wrong…so please chime in with your thoughts. I’m guessing someone will mention “saftey”, but I honestly don’t know how 3d printed cable chain could be unsafe in the real world. Maybe if enough people feel as I do they will change this rule next year.

By the way if you don’t know what cable chain is, it is simply a special shaped chain that allowed wires to be safely run inside for protection and management. Just google “cable chain wire management”

I am NOT for rules that give certain teams more advantages than others, but this limit on 3d printing cable chain isn’t really doing anything to keep the playing field even. Whether I buy or print the stuff myself, it is cable chain…its not complicated stuff.

By the way, the vex forum is awesome. The community is remarkable and I have learned a lot from many of you on here. I’m glad to finally be a member and hope to join your conversations often! I am the teacher for teams 4149G & 4149C from Minnesota. We have been doing VEX for 3 years and have made it to Anaheim the past two years! Been fun!

Karthik’s point was about the total allowance of 3D printed material on the robot, which is designed to level the playing field for college teams so that teams don’t 3D print their entire robot. As soon as you make a 3D printed material exception for cable management, then you have exceptions for fasteners and brackets and structural members.

I will say that the new rule allowing COTS cable chains is a bit bizarre, but I guess the prospect of 5-foot elevators and dangling wires scared enough people at VEX.

There are lots of great little CAD projects for teaching students about the abilities of 3D printing, but unfortunately 3D printing is currently outside the scope of most high school VEX teams, and therefore the entire competition. I’d love to see it be allowed in the future as 3D printers get cheaper and more ubiquitous, as it really is a wonderful technology.

“high school teams”
The official question was asked for an exclusion for College initially; not high school.

I realize the original question was based on VEX U, however, in Karthiks reply he specifically states “This would definitely not be permitted in the VRC”.

I appreciate your reply, however I don’t feel that it really takes into account what I was speaking about. My point is that there is no “leveling the playing field”. Cable chain is already allowed, so if I can make my own on a 3D printer, what is the harm in that? I can’t think of a single negative aspect to it, only great learning opportunities for the students. It does not give me any greater chance at winning a match than any other team. I feel like we don’t always think rationally about what should and should not be allowed. But I really do appreciate the replies, please keep them coming! I will gladly admit I am wrong if that’s the consensus, just thought it was a conversation worth having.

Given that many hobby-grade 3D printers cost about the same price as a VEX Starter kit, allowing printed parts could potentially provide a huge advantage to teams with access. Granted, I don’t see printed cable chain providing that much of an advantage, it is an advantage nonetheless.

But the same could be said about any existing VEX part. Why not make 3D printed gears, linear slide trucks or bearing flats. Once you allow 3D printed parts to be substituted for one item then it’s an opening to allow it to be substituted for anything.

Then where is the line drawn on what type of printer can be used. I have access (in theory) to a $750,000 printer that can make parts from a variety of materials. How can VEX determine what type of printer was used during inspection. If the quality of my parts are “too good” would they be disallowed?

I found this bizarre as well. Why suddenly zero in on cable management, I was going to buy some just to try it out but the good stuff is expensive and there is a huge range of quality available. It would have been much simpler if VEX had chosen one type and added that to their inventory so we were all using the same part.

Could you please be specific on how it is an advantage? Remember, you can legally purchase it from any manufacturer. Therefor everyone has access to it.

I feel that 3d printing cable chain is different specifically because VEX does NOT sell it…therefore I am not substituting3D printed parts for a VEX part. It just seems weird that I can legally by some crappy chinese cable chain on ebay and legally use it on my robot, but I can’t make my own. Doesn’t that strike anyone else as odd?

I don’t think the argument of “if you allow one thing than where do you draw the line” really applies…again, because VEX does not sell cable chain. I don’t think it would be acceptable to 3D print vex gears, metal, etc. In order for that to be feasible and strong enough you would need a VERY high quality printer. On the other hand, cable chain could be printed on a $400 3d printer.

I hope I am not coming off as rude/argumentative…because that is not my intention at all. Thanks to those of you who have responded…keep them coming!

The only thing that’s strikes me as odd is that VEX wasn’t more specific with the specifications. I would have preferred we were given a single manufacturer and product (in a similar way that pneumatics are constrained) rather than the completely open ended ruling that cable management is now allowed.

touché…can’t really argue with that logic. (But I still want to print my own! haha)

Agree with that although it seems the intent of the GDC ruling is quite specific. Don’t forget it’s a global competition so what’s available in the US isn’t necessarily easily obtained elsewhere so if it’s locked down to a particular manufacturer for example that’s not so good.

If 3D printing is your thing and VEX isn’t enough of a challenge then take on FTC instead (or both?). You can 3D print your whole robot it’s that’s something that seems sane from your viewpoint. I run teams in both VRC and FTC. Having constrained parts in VRC is just a different learning experience for students and is something 7682 teams value because in a way it raises the bar since it’s harder to differentiate from others and remain competitive at the same time. FTC on the other hand is becoming more and more open and we don’t see design convergence so much but some of the top robots are pretty slick machines as a result. Go read part 1 of the 2014/2015 FTC game manual.

I actually approve of this in order to open the market to the consumer in order to create more competition for a competition.

That is a good point. FTC is much more open. However it isn’t practical for me personally. It seems to be a program that requires much more time and money. I have very little time the way it is. I teach at a school with 70 high schoolers total (7th-12)…yes you read that right. I teach 7 different sciences…life, earth, physical, biology, anatomy, physics, and chemistry. I also coach basketball and VEX robotics. Vex allows us to build slowly throughout the year at our own pace, when I have time to meet with my robotics students. Our program is all extra curricular…no in class time. If I understand FTC correctly, you only have 6 weeks or something to make a robot and it costs many thousands of dollars each year. I wouldn’t have enough free time within the 6 weeks to get a robot built and being a tiny school we are pretty limited on funds.

I do think it is an awesome program though! Just doesn’t quite fit our schools needs.

As you may have seen I recently asked Karthik about using 3d printed decorations (logo’s or such) on the robot, as long as they did not provide any function other than decoration. He approved of 3d printed parts for this purpose. I figured it would be ok, but since 3d printed objects seem to get extra scrutiny in the VEX world I thought I would ask. Just wanted to mention that here so you all know…I think that’s a good start to at least allow teams with 3d printers to incorporate the skills and technology of 3d printing into their robot in some way!

You probably need to do a little more research because from what you appear to understand is flat out wrong so I’ll fill in a few blanks.
The FIRST pilot program called FVC (FIRST VEX Challenge) is where VRC (what most refer to as VEX) spawned from. FIRST switched robot platform from VEX to TETRIX some years back and officially named the competition FIRST Tech Challenge.

FTC and VRC are similar from an outsiders perspective, they’re played on the same size field with a 2 on 2 alliance of 18"x18"x18" robots. Cost wise there’s not a big difference and some FTC teams make few if any custom parts opting instead to just use items from their TETRIX or MATRIX sets.

The FTC season starts early September and the world championship is at the same time as the VEX world championship (give or take a week sometimes). I think you’re probably confusing FRC (FIRST Robotics Competition) with FTC. FRC is constrained to a 6 week build season and is more costly than VRC/FTC for sure. FRC teams spend a large amount of time working on stuff during the off-season too so although build season is 6 weeks it’s kind of wrong to call it a 6 week program.

Not sure if you have these links already but for completeness here they are:

My own experience in running both VRC and FTC teams is that funding wise it’s sometimes easier to get suppliers to donate raw materials like aluminium extrusion and bearings for example than cash to buy pre-punched VEX parts. On the other hand being able to go “VEX shopping” and being done pretty quick is well suited to those with little time!

Sounds like you’ve got your hands full there and I’m sure the students will be appreciating all the work you’re putting in :)](


My own experience in running both VRC and FTC teams is that funding wise it’s sometimes easier to get suppliers to donate raw materials like aluminium extrusion and bearings for example than cash to buy pre-punched VEX parts. On the other hand being able to go “VEX shopping” and being done pretty quick is well suited to those with little time!

Sounds like you’ve got your hands full there and I’m sure the students will be appreciating all the work you’re putting in :)](

I was most definitely confusing FTC for FRC. I didn’t realize what FTC was. It sounds very interesting and worth looking into. Thanks for educating me!

jpearman’s done a pretty good job saying everything I was thinking, but I’d like to add a bit more.

I don’t think anyone’s going to convince you that you’re wrong, because you have very valid points. But all of us here are used to VEX and its oddities and we’ve grown to accept certain things.

I’ll use an example to illustrate what I’m trying to say. You’re not allowed to create your own screws, but you are allowed to buy them as expensive and high-quality as you would like to. But they’re still just screws. The rule allowing any COTS screws only exists because they are just screws. It doesn’t matter. Any screw will do the job, and it doesn’t matter if VEX sold them or not. It’s the same thing with cable chain.

Cable chain fills one purpose, and any cable chain you buy will do exactly the same thing. You aren’t allowed to make your own cable chain because you don’t need to. You aren’t allowed to make your own screws because you don’t need to.

Now all of that you already know (and doesn’t directly address your points), but here’s what I think the difference is between your point of view and VEX’s:
I once had to explain to a very irate parent (I was head ref, so had to deal with this) why I didn’t DQ his son’s opponents, even though they didn’t have a backup battery on their robot, and were clearly breaking the rules. Yes, I could have prevented the team from playing, but it wasn’t in the spirit of VEX to stop some kids from having fun because their team didn’t have enough 9V battery holders. In the same way, VEX isn’t about fabricating your own parts. It’s about finding creative ways to put parts together to accomplish a goal, it’s about seeing how other people have made amazing things with the same exact parts that your robot is made of.

Students shouldn’t have to worry about tolerances and joints and lubrication to work with VEX. I’m not saying those aren’t important skills to learn, and I do believe that you shouldn’t be punished for teaching them, but at the same time, it’s very important to understand that the world is not a fair place, and VEX is only trying to do what it can to keep the competition fun.

[sorry if this post turns out to be really long, but you’re looking for objective reasoning in a strange and subjective world, and it’s really hard]

Very valid points, I do see where you are coming from. Thank you for your input!