can string be used on the robot?

Me and my team want to use string as a grappling hook can we?

I’ve seen teams using the high-strength chain, the long pieces of Velcro (yes, this is a legal part, see http://www.vexrobotics.com/products/accessories/structure/275-1257.html), and even braided PWM cables.

also one of our sister teams has been using braided anti slip mat cut into strips roughly 5/8" thick.

I think vex should make some nylon rope and introduce a pulley kit. High strength chain is great for transferring rotational energy but they have a tendency to snap when used to lift things. Pulleys and rope specialize in linear movement. Nylon rope can handle the strain of lifting large weights and puts the breaking point back to the metal structure where It always should be.

That would be a great addition next year. :smiley: Please consider.

Maybe weave surgical tubing until you reach the desired effect?

I assume that you are talking about pneumatic tubing. This does not work, as it is far too strechy to use for this reason, even if you do braid it.

I know VEX used to sell nylon rope, because last year we used it on our robot at one point and it was legal. I’m not sure if its still legal though. They do NOT sell it anymore but they used to so idk if they would allow it if you bought it from them before or if they won’t because they no longer sell it. You might want to ask one of the VEX ppl/Engineers.

I believe they are talking about the Latex (surgical) tubing. ( http://www.vexrobotics.com/275-1262.html ) And I think you may be talking about the same thing, as it is stretchy, whereas the pneumatic tubing isn’t at all. ( [http://www.vexrobotics.com/products/accessories/motion/275-0447.html )

~Jordan](http://www.vexrobotics.com/products/accessories/motion/275-0447.html ))

Actually last year VEX made string illegal, for the whole competition year if I’m not mistaken. Up until then string had always been a legal product to use.

~Jordan

yes, legomindstormmaniac is correct
there were some confusion in the first competition because it was "legal last year (elevation)
but it was sorted out when somebody specifically asked
so generic “string” is still illegal (they are not selling on the vex site)

but there are many other materials that you can use as string such as
braiding narrow strips of anti-slip mats
using the strips of velcro
using pneumatic tubing
using latex

  • more :stuck_out_tongue:
    just use your creativity!
    it wont be called “VEX” if you don’t have to think :wink:

We’ve found in our experiments with hanging that PWM cable can hold our ten-pound robot fairly easily. Not terribly useful for tying things together, but if you need something to take both linear and rotational force PWM cable is great.

Last year we used a piece of high strength chain in which we ziptied every link to the links next to it. It was incredibly sturdy. Also, six inches of it took two hours to take apart.

) And I think you may be talking about the same thing, as it is stretchy, whereas the pneumatic tubing isn’t at all. ( [http://www.vexrobotics.com/products/accessories/motion/275-0447.html )

~Jordan](http://www.vexrobotics.com/products/accessories/motion/275-0447.html ))

My mistake. you are correct.

Also, what is wrong with using zip ties zipped together? I’ve never tested it, but it doesn’t seem like a bad idea. And they’re pretty cheap, so you can throw them away instead of spending lots of time unlinking chains.

The ends of the zip ties can get a bit annoying to deal with because what you end up with is less or a clean length of string and more a weird pieced together… well… bunch of zip ties.

I am shocked to hear that anyone needs to add any strength to the HS chain. It is spec’d at about 50lbs of tensile strength… I am building a Vex robot what are you building?:smiley:

~DK

Zip ties zipped together looks ugly and bunches in weird ways. Plus sometimes it gets stuck to things, and one bad ziptie can screw you over.

With reference to the chain comment, HS chain is pretty unwieldy for a winch because it’s so huge. I wouldn’t want to fit a 36" roll of it somewhere on a robot, let alone try to get it to roll up the same way consistently.

  • HS chain doesn’t roll up well.
  • A winch drum has variable diameter as cable adds up.
  • HS chain fits a HS spocket nicely.
  • A HS sprocket has constant diameter.
  • 36" of Vex chain is less than 2 Vex robot diameters in length
  • Vex chain bends in only one plane, so excess chain needs to be stored in one plane, not just piled in a bucket like logging chain, or spiraled like winch cable.

A couple of chain pulleys and some lightly stretched rubber bands could be contrived to hold the slack chain more neatly in a zigzag than a roll, and the elastic helps contribute to the lift.

You are allowed to use rope from the winch and pulley kit.

worst case, use the pully without a motor. String is attatched but you dont have to motor it.