Durability of tetras

[Jon K.]

Someone correct me if I am wrong, but I also believe that the ones FIRST will be using are of a different material then the PVC ones we are all building ours out of. From what I heard, they are using a plastic that lawn furniture is made out of, and therefore there are probably some different characteristics.

[Wetzel]

Originally Posted by Swampdude

All I can say is I hope they stock a lot of extras at the competitions. Our cap system is tearing them up. It's not as much the bot's fault as it is the fact that these things are heavy with a rather weak joint. I don't think they were designed with rapid play in mind. Then to compound that with a couple bots fighting over one, there's going to be a big pile of dead tets after each competition. Or at least those clover things. They need to make metal ones.

Perhaps you need to rethink your robot design. You have a system that you like, but is "tearing them up." Because your design was breaking the official tetras, you made stronger ones to practice with. However, the tetras are as they are. With the Sterlite bins in Stack Attack, FIRST intentionally chose a weaker container as part of the challenge. Having custom injection molded parts, and lots of them, made it is unlikely for FIRST to spend a lot of money to redesign the major game piece now.

You don't get to engineer how strong a human chest is, you need to engineer your car to not exceed the loads a chest can take in a car accident. A foot can only take so much energy, you need to design the boot to keep the energy below that threshold.

In FIRST as in life, there are design criteria that can not be changed.

Wetzel

[M. Hicken]

i beat the snot out of our stock. A little pvc clue and they will not fall apart for me. I constantly take out some anger on them if there is nothing to beat with the BFH. Other than scratches, i have noticed no real damage. I guess that if one drops it from 10-15' up, the pvc might shatter, but since i sell the stuff at work, ive noticed it isnt easy to break.

[Pielord]

Originally Posted by tkwetzel

Seeing all the pictures of the robots come together, I have noticed that those tetras really will be extended pretty high into the air. It is also a good chance that many will fall from great heights also. It seems that they may break easily after being dropped from 10'+ a few times. Has anyone dropped a tetra from a height as such and noticed any damage? Or has anyone noticed any damage at all to tetras that you have built and tested with?

we havent broken ours yet but thats probubly because we havent practiced yet

[elknise]

Today at our practice competition, a bunch of the tetras broke. None of ours broke because i believe we were the only team that clued the PVC, used IFI clovers, and used T-Nuts. With a bunch of them, the caps just shattered. If you are running a practice competition, make sure to HAVE EXTRA CAPS! There were extra caps where we were, so our team fixed all of the ones that broke.

[Winged Wonder]

i cant even tell you how many tetras we've broken in practice. while switching out different drivers, i think i might have racked up the most tetra casualties ^^; we've made clovers out of lexan and aluminum, and they still come apart at the bolts or rip in the center section of the clover. its has nothing to do with how we perform, its just the wear and tear of constant handling. we had a PVC goal just collapse on us just because of the wind.

-shrugs- i guess thats life... and the drivers will just have to be a little careful, because i dont think that they'll start a match over just because the tetra you are handling decided to collapse right as you were about to cap. sure that can directly affect the outcome of the game... but if it happens often, there may not be anything anyone can do about it and you'll just have to deal with it.

best of luck everyone... i'm praying competition tetras hold up well.

[BaysianLogik]

I'd say if we drop them from our full height, or swing them from any height, they have a 5% chance of breaking. We've broken and had to fix about 3 so far. The vision tetras especially, since our zip ties break pretty easily

[Kyle Love]

I, myself, broke about 2 or 3...I can't imagine the total we have broke. But then again, our end caps were made of Lexan...what could I expect.(BTW..the one metal capped one we have hasn't broke yet...so I think the FIRST ones will be unbreakable)

[Nate Edwards]

After the stuggle to find end caps that actually fit and enough of them to make like 12 tetras, we have only broke one or two at practice, and we too are using the pvc glue, but those clovers snap easily, our mentor broke one in his hand, and we broke several of them dropping a single tetra. We machined our own and those didn't work either, so when we saw the plumbers tape idea we used it and combined with the glue they were among the only tetras at the Corvallis Scrimmage to not take a large beating.

We however did take some of the weaker tetras and break them apart accidently many times. But in the last 5 or 6 matches we competed in we learned how not to break the tetras, slow non sudden movements and not dropping them leads to a good scrimmage.

[Tim Arnold]

Originally Posted by Swampdude

All I can say is I hope they stock a lot of extras at the competitions. Our cap system is tearing them up. It's not as much the bot's fault as it is the fact that these things are heavy with a rather weak joint. I don't think they were designed with rapid play in mind. Then to compound that with a couple bots fighting over one, there's going to be a big pile of dead tets after each competition. Or at least those clover things. They need to make metal ones.

Yeah, expecially when your throwing them across the field...

[Specialized]

At the UTC invitational yesterday, there was a dedicated "tetra-fixer" I will call him. He has a ryobi drill with a socket driver on it and he was fixing all or any of the broken tetras. If tetras break, it isnt a big deal to replace it as there were no more than about 15 or so on a field at once, the most that I saw.

[Jon K.]

Originally Posted by Specialized1248

At the UTC invitational yesterday, there was a dedicated "tetra-fixer" I will call him. He has a ryobi drill with a socket driver on it and he was fixing all or any of the broken tetras. If tetras break, it isnt a big deal to replace it as there were no more than about 15 or so on a field at once, the most that I saw.

They also only broke a couple of them from what I saw, altho the green part of the vision tetras had to be replaced a few times, as they were using some sort of green sticky paper or something which would just peel off.

[IronVulture]

our practice tet end-pieces were just lexan, so not the sturdiest stuff, but we murdered those things, of the five built, none survived. Honestly, just a little toss (across the room) or drop (from the ten foot ceiling) and the things just came apart like the pipe cleaner tetras we made for grabber brainstorming.

[XtremeEagle04]

So to revive this old thread, how do you feel the tetras held up? I know that while our team was at FLR we only broke 2 tetras, at GLR we broke 3 (taking into account that we were stacking a lot more) and at Nat's we only broke 1. I noticed that FIRST wasn't using the same color clovers as the white ones that they supplied us with. I cant help but wonder if the color that they used to dye the clovers affected how they handled stress... possibly FIRST was on to this because many of the clovers at Nat's were either white or made from a different material as the original ones, they seemed to stretch more rather than brake

Also, at GLR the tetras that broke when we stacked them were not counted toward the score for our match, shouldn't this fall under field malfunction and thus we be awarded our points? it never really mattered much with the outcome of matches, either we were ahead by enough to not have to worry about it or behind so far that it wouldn't have helped anyway..

[Kyle]

I think the tetra held up OK, it seemed like they only broke at the worst possible time like when they are placed on our bot or when they are being stacked. I helped repair the tetras at the Philly regional and most held up pretty good for the most part. The only problem was those clovers, they would break or the screws would strip inside the pole and the tetra would become loose and unplayable.