VEX EDR or Lego EV3 for high school robotics elective?

[mistersands]

For background, I teach in NYC. Many students in my elective class have never been exposed to robots. There is a huge variety in English and Math ability. Some barely speak English. Some have not passed Algebra 1. Others are taking AP English and AP Calculus. Because of the elective status, most students are just put there because it fit their schedule and/or they needed a science credit. Others are on my FRC team and wanted to try the class.

That said, is Lego too remedial? I am using VEX now and have the opportunity to try and switch. I find vex breaks very easily. Maybe that's just the students not taking good care of the equipment. but I've lost so many pins on the connectors for the 393 motors, not to mention that all the screws get stripped very easily. The teeth on the plastic gears break, especially on the 12-tooth gears.

I want something that will let the advance kids be advanced, and the weaker students still accomplish something. I'm finding with VEX, the weaker students are having trouble getting anything together.

Thoughts?

[carpedav000]

If you like VEX and dont want to do Lego, I would suggest Tetrix. It is as advanced as VEX, but the parts are very hard to break.

[colin340]

VEX VEX VEX so many more competitions!! at least round here

[paragon571]

Lego breaks easily too. I have worked with vex, lego. and tetrix.
I say for easy go with ev3 because it has simple step by step guide and they can program right on the screen of the bot.

[Gregor]

Originally Posted by paragon571

they can program right on the screen of the bot.

Have you ever actually used this? It's atrocious and not even worth the effort.

I've spent many hours with EV3, and was impressed with its ease of use and robustness over the old NXT system, especially with younger or inexperienced students, but I don't have any experience with VEX or Tetrix.

[eddie12390]

Originally Posted by colin340

VEX VEX VEX so many more competitions!! at least round here

I second this. VEX is super fun to compete in and (provided that your careful enough) the parts don't break that easily.

[JesseK]

Originally Posted by carpedav000

It is as advanced as VEX, but the gears are very hard to break.

Fixed. Everything else is typically the opposite, in my experience with an average of 8 FTC teams a year. With TETRIX there as many or more failure modes than there are for VEX. With TETRIX, the students do all of their own wiring, which is a liability nightmare without the proper guidance. Motors & servos are pretty easy to break or burn out in TETRIX. Metal is, well, metal.

VEX even solves the 12-tooth plastic gear breakage by offering a better, metal one. Maybe we can get JVN to respond for whether it'll ever be an option, but it seems like socket heads rather than button heads would resolve the bolt-stripping issue to an extent? If it's a non-competitive environment the OP may be able to just purchase the #4 bolts from a hardware store. Off the top of my head I don't know what's allowed in VRC though.

[Dave Campbell]

I have 16 VEX kits in my lab and I am finding that most of the same problems - Motor wire pins breaking very often is my biggest complaint. We have them stored neatly and the students take fairly good care of the parts. The pins are just brittle. I have not had the gears break, but the clutches seem to round out with the pins or square shafts. I attribute this to the screws loosening either on the motors or on the frame and slightly disengaging the shafts from the clutches.
All problems aside, I still like the VEX kits over Tetrix and LEGO. I have a few of each of those other kits and the VEX kits offer more flexibility with differentiating the instruction for the students. From basic machines- levers, inclined planes, etc, to programming complex autonomous machines.
I will be fixing about 8 to 10 motor wires each quarter, but I have bought pins and can salvage what I need easier than returning the motors to VEX for repair or replacement.
Best of luck with your decision.

[Underdog_19]

Originally Posted by Dave Campbell

I have 16 VEX kits in my lab and I am finding that most of the same problems - Motor wire pins breaking very often is my biggest complaint. We have them stored neatly and the students take fairly good care of the parts. The pins are just brittle. I have not had the gears break, but the clutches seem to round out with the pins or square shafts. I attribute this to the screws loosening either on the motors or on the frame and slightly disengaging the shafts from the clutches.
All problems aside, I still like the VEX kits over Tetrix and LEGO. I have a few of each of those other kits and the VEX kits offer more flexibility with differentiating the instruction for the students. From basic machines- levers, inclined planes, etc, to programming complex autonomous machines.
I will be fixing about 8 to 10 motor wires each quarter, but I have bought pins and can salvage what I need easier than returning the motors to VEX for repair or replacement.
Best of luck with your decision.

How do you fix the broken pins? We have that issue constantly.

[Dave Campbell]

Remove the wires from the plastic housing, cut wires, re-crimp new pins on the wires, then put back into the plastic housing.
On the 3-wire connectors, I have my students just cut the ends of PWM wires and solder new connectors onto the VEX parts. Good experience for them to learn to solder and use heat shrink tubing for a clean finished look. Can be expensive replacing PWM wires, so I have ordered more pins and housings from Digi-Key (thanks to the FRC Digi-Key voucher)

I'll look for part numbers for the pins and housings once I am back in my lab and post for your reference...

[Allison K]

Just a thought... have you considered VEX IQ? VEX IQ officially targets kids ages 8-13 I think, however my high school kids love the IQ kits when they get to use them.

EDR and IQ could probably be used in tandem to provide options to students of varying interest and ability, allowing you to address less experienced builders without having to invest in an entirely new set of equipment. I've been told (I'll double check tomorrow when I have both kits in the same place) that the holes are on the same pitch so the kits could theoretically even be used on the same robot (I'm not sure I'd recommend that, just saying I think it's possible).

EDR and IQ feature the same build style, utilizing beams, plates, pins/screws, and standoffs to assemble mechanisms, so most designs could be built equally well with either system. With some prior planning lesson plans could probably be adapted so that students could utilize either system.

IQ is nice for new designers and builders as it's relatively forgiving if a rebuild is necessary. The snap together nature means that less time is spent on assembly and more time can be spent on design/testing/iteration. It's also very beginner friendly with its out-of-the-box teleoperated control.

Also, if you do any software both kits can be programmed in RobotC, so that might be handy.

[Sperkowsky]

Honestly I wouldn't go lego just because even if the students are learning it will turn them off. (I'm lived most of life in Queens) what I think a lot of people here don't realize Is the odd maturity of NYC kids. They are Street smart and good kids (most of the time) but a lot of them could care less about whether school property breaks). I think tetrix Is the better option because of the fact that you do your own wiring (high school students can handle it and it's an actual skill)

Though have you considered Ftc? Next year my friend told me they are using an android interface and I feel it's hard enough that High school students won't look at it and laugh but easy enough that the less motivated students can learn.

I'm no expert but I understand NYC teens because I was one.

[Foster]

Stick with VEX metal since you have it.

Look here http://www.vexforum.com/showthread.php?t=80950

for how people have fixed the broken pins issue. The VEX forum is great for answering your kinds of issues.

And while I love VexIQ the motor/sensor cables are like phone cables. The little tab can be torn off. But since they are left hand DEC format, the connectors / cables are not easy to replace. The replacements from VEX are not that expensive, but they are the only source.

[colin340]

Originally Posted by JesseK

If it's a non-competitive environment the OP may be able to just purchase the #4 bolts from a hardware store. Off the top of my head I don't know what's allowed in VRC though.

YUPPP YOU CAN!

<R7> Robots are allowed the following additional “non-VEX” components:

c. Any commercially available #4, #6, #8, M2, M2.5, M3 or M4 screw up to 2" long, and any commercially available nut to fit these screws.

[Rebecca Wasmer]

Currently, I am working with a school district just getting their foot in the door as far as robotics is concerned. I had them purchase quite a few EV3 kits because they are looking to incorporate them at all levels of their school district and are also looking into starting FLL teams. I have found that the high school students I am currently working with are loving the EV3s because of their versatility and with the current number of tutorials already available, they were open a kit and build a robot within their first class period. They weren't intimidated by their lack of experience and were able to just jump right in. (A few did admit to me that they were skeptical that they would like it at first, but now they're hooked) We're set to have a Sumo-bot competition at the end of the year, now, with different awards for different types of designs.

That being said, I ran an FTC team a few years ago and we used the Tetrix system and I grew up in a high school that had VEX components available and that were used in the "robotics" class offered there.

With a mix of students that diverse, it's hard to find a system that meets all of their needs, but I would have to agree with everyone here that VEX or FTC would be the way you want to go. From what I have been hearing about the route FTC is taking, you might be able to entice some kids into learning more programming through that because if it is on the Android platform, then you can always use the "then you can make apps!" as a way to draw kids in.

A bit of your decision should also be based on how much programming/coding you want to the students to learn. With the EV3 systems it is all block based and pretty simple to use regardless of how much math a student has done or how good they are at it. (I have some first grade students currently programming EV3s) With FTC they are moving to Java programming this year. I'm not as familiar with VEX, but what I did in high school was mostly plug and play, which can be nice when you want to focus more on robust design and the physical aspects of robotics rather than the software end.

Those are just my thoughts on the matter. I'm sorry if it's a bit of a ramble. Hopefully this is helpful, I'm just getting my foot in the door with this whole teaching thing. Good luck!