I’ve read a few posts on the forum regarding the use of string in attaching parts. Rope or string is not a legal component in this game ("<R7> Robots are allowed the following additional “non-VEX” components").
Rick is correct, I had noticed this in a few posts, including the most recent Q&A entry. As such I made the following note in my response:
“Note: Many teams have mentioned “string” in their discussions about potential VEX Clean Sweep robots. Just so there’s no confusion, as it currently stands there is no string in the VEX product line and no provisions for the use of string in <R7>. Teams who wish to use string like devices will have to exercise some creativity in their material usage.”
On the other hand there are zip ties, Pneumatics Tubing (in 5’ lengths), Velco (in 5’ lengths), rubber bands, latex tubing, and if people really want to stretch, 18’ lengths of tether cable.
If Vexnet does come out with robot -> robot communication the “connected by string” rule could become even more interesting in the future. As a hobbyist, I really hope vexnet has that feature, but it does create some interesting possibilities from a school age competition standpoint.
I don’t think tether cable will get past an inspection; but I could be wrong - And, I admit I’m too lazy to go over the rules with a fine tooth comb at the moment.
Last year I had a tether cable on my robot, because my team was somehow short on the yellow rx cables, but I was not able to pass inspection.
although “string” is not in the components list nylon roping is correct?
No – not this year.
Nope. I hope everyone reads the Robot rules very carefully. Just because something was legal in years past, does not make it legal this year.
Does anyone know why they disallowed it this year? It didn’t seem like anyone abused that rule in the past two years, but i suppose they can write the rules however they wish.
Well it’s up to the GDC now isn’t it?
I mean honestly, I would mix it up as well.
I see that teams are extremely dependent on rope, and by not allowing rope, IFI made teams think a little bit more outside the box.
Com’on guys, they gave you hight strength chain and a way to fix it to metal, do the math! You don’t need string, they made better parts.
High strength chain can’t wrap around a sprocket multiple times like rope around an axle. It quickly becomes bulky and cumbersome, nor was it designed to do so.
and no one would buy “vex string”
I’m disappointed that string is gone… it aids the design of many useful and interesting mechanisms, including elevator lifts and winches. Yes, one could use a servo extension cable, with the ends chopped off and with the three wires stripped apart into individual lines, or could slice off a very even slice of tire material, I suppose… but it made sense to allow string.
String has been stimulating imaginations for millenia. So while deferring to the GDC’s authority to ban string, I simply ask why stop now? Perhaps it caused a problem of which I am unaware?
Bring back the string for next year, please.
Humm, lets see… I have already seen a team this year use the tank tread (basically wide chain) for an elevator lift and any winch just ends up lifting an arm (level to be exact). I would love to point out why gears do this job best, over the small chain, large chain and any kind of string but I don’t have time to get into that rant right now. The point remains, if you really, really want to cut up PWM cable or the rubber tubing to make your own “Vex” string - who am I to stop you.
and you also get “identical” wires to those of stripped PWM cables
I’m sure there are many creative work-arounds for the “no string rule”. Certainly the tank tread can be made to do it given that string isn’t allowed (and I’ve suggested a few other options, too), but string could do it better in many situations (internal rigging in particular) and at much less expense. (Cost of string << cost of tank treads)
I was unaware that winches could only be used to lift an arm, or that gears always did that job best in all applications… or perhaps that isn’t exactly what you meant?
The beauty of string is that it can be used in many different and creative ways. It certainly isn’t NECESSARY for any given VEX game, but given that it is very useful and extremely low-cost, it would be nice to see it included in future games as an allowable building material.
Sure, let me reword that. In my non-professional opinion: gears translate force and motions more efficiently than any other form of linkage (chain, string, etc.).
When one uses the word “efficiency” it refers to energy loss within a system.
I’m not sure if your generalization is accurate based on this definition…
And I also heard that sprocket/chain systems are more efficient than gears - can someone clarify (or provide numbers)?