What's the best rope?

[engunneer]

You initial post on this subject disqualified the rope because a glass bead isn’t flexible (even though glass is a liquid?) Blue note completely conflits with you definition of flexible.

Let’s review the tape:

As an inspector, that rope would not pass my inspection and would be brought to the LRI as it contains glass beads (which are not fibers or flexible, per I04).

I was not saying the rope is not flexible. I was saying the glass beads that are a component of the rope are not themselves flexible, and they also not fibers. The rule (not the blue box) is pretty explicit. “consist entirely of flexible, non-metallic fibers” seems pretty clear to me. If a flexible rope contains materials that are not flexible OR are metallic OR are not fibers, then the rope by definition does not “consist entirely of flexible, non-metallic fibers”

On a side note, glass is not a liquid. (Reference)

A fiber is really just a small piece of anything. see webster below.

Definition of fiber
1
: a thread or a structure or object resembling a thread: as
a (1) : a slender root (as of a grass) (2) : an elongated tapering thick-walled plant cell void at maturity that imparts elasticity, flexibility, and tensile strength
b (1) : a strand of nerve tissue : axon, dendrite (2) : one of the filaments composing most of the intercellular matrix of connective tissue (3) : one of the elongated contractile cells of muscle tissue
c : a slender and greatly elongated natural or synthetic filament (as of wool, cotton, asbestos, gold, glass, or rayon) typically capable of being spun into yarn
d : mostly indigestible material in food that stimulates the intestine to peristalsis —called also bulk, roughage

So what exactly is your reason for saying this isn’t legal?

does a small round glass bead resemble a thread? I would say no. That already disqualifies your definition at definition 1 before you even got to 1©. in any case, 1© calls for a “slender and greatly elongated” filament, which a small glass bead also does not resemble. Therefore, my reason for suspecting that it is not legal is based on the very definition of a fiber that you provided.

Lastly, at no point did I say definitively that it is illegal, only that I would question it as an inspector and get a second opinion from my boss at the event, who is the LRI. If the event LRI is unsure, he or she can take it up to the CRI, who is on call to all LRIs during an event, or to FRC HQ. that is the process.

[Fusion_Clint]

I reckon we will have to agree to disagree.

The rule clearly intends the rope be flexible to less than 12 inches vertical from the point it is held.

They will have to give exact tolerances for a fiber and it be measured with an optical/laser comparator to fit your definition. BTW where does it say the bead is round?

[Lil_Lavery]

Velcro is not composed of twisted or braided strands, unless you consider individual polymer molecules strands and are looking at it under a really good microscope. Feel free to ask on Q&A, but this seems like a pretty solid no to me.

[engunneer]

The rule clearly intends the rope be flexible to less than 12 inches vertical from the point it is held.

I don’t dispute that, however my issue is not with the rope itself being flexible. I’m sure this one is. My issue is that it must also be composed entirely of flexible fibers.

They will have to give exact tolerances for a fiber and it be measured with an optical/laser comparator to fit your definition. BTW where does it say the bead is round?

I don’t believe they will need a laser or even a specification to determine that a small glass bead is not a “slender and greatly elongated natural or synthetic filament” based on the definition that you provided. The linked rope states “50,000 minute glass beads to the square inch”. I am indeed assuming that means a sphere, but even if they are a diamond or a heart or a cylinder, they are not going to be “slender and greatly elongated”, nor “filaments”.

I don’t want to have a team go buy this rope (since talking about it, they have gone from 201 to 171 feet in stock, so i suspect three teams bought 10 feet each!), develop a system that relies on it, and then have it non-functional because of an inspection issue. All inspectors have the goal of making sure everyone gets on the field and is playing by the rules.

Please let us know when Q&A answers your question about this material.

That being said, and after typing up a long reply with my reasoning (small glass beads are not flexible filaments), I went and found the manufacturer’s website for this product: http://shop.pmirope.com/12-5mm-retro-rope-ez-bend-yellow-reflect-30-meters-rr125yg030ev

Reading that, they don’t talk about glass beads at all. they talk about “Retro reflective filaments” which are not glass beads. as a result, I think this rope is probably legal now.

Am I willing to admit that my answer changed because of new evidence? yes.
Am I willing to admit I was wrong? Yes and no. Yes, because the final material looks fine, now that there is more information, but No because given the originally linked page as the only documentation of the material, I don’t think the material met the letter of the rule.

I suspect we still disagree as to why the material is legal, but i think we both now agree that it probably is.

[carpedav000]

Velcro is not composed of twisted or braided strands, unless you consider individual polymer molecules strands and are looking at it under a really good microscope. Feel free to ask on Q&A, but this seems like a pretty solid no to me.

It is the instant you braid about three strands of it

[Koko_Ed]

For tha sake of a smooth running event I really hope people just stick with the field rope.

[cpapplefamily]

Does I04 and figure 9-1 really depict that a strap is a rope. Seem to eliminate difficulty and challenge of climbing a round gym rope. I admit I need more time to read and read again. At first impression I suspected the rope rule was going to be to have rope as similar to the 3 strand twisted rope depicted in the release videos.

Interpretation would be a 1/4 rope would be ok or 1" strap. The challenge is to engage the line and then is simply becomes a cable winch.

[engunneer]

yes, the manual shows a strap as a legal possible rope, and even shows examples of ropes with knots and loops.

I honestly think they suggested it to reduce the Q&A on the topic about whether ropes need to be round in cross section (they do not).

grabbing and climbing any dangling flexible object seems tricky. I like the way they designed this.

[Kevin_Sevcik]

For tha sake of a smooth running event I really hope people just stick with the field rope.

Yeah, but if I climb my own rope, I can just pull the rope and robot off the field together and don’t have to fiddle with whatever system for untangling the robot without power. Teams bringing their own ropes can’t be that much more annoying than the standards, can it?

[engunneer]

I like the idea of off-field rope removal, but i think you’ll have a hard time getting the rope off the davit if the robot is actively against the touchpad and the section of rope between the robot and the davit is under tension.

[cpapplefamily]

yes, the manual shows a strap as a legal possible rope, and even shows examples of ropes with knots and loops.

I honestly think they suggested it to reduce the Q&A on the topic about whether ropes need to be round in cross section (they do not).

grabbing and climbing any dangling flexible object seems tricky. I like the way they designed this.

I’m surprised. Now with this discovery a team can make a drum winch. Original presentation made us feel we are climbing more like a human would. As you climb you pass the rope through not coil it up.

Yes grabbing the line could still be tricky

[ToddF]

you’ll have a hard time getting the rope off the davit if the robot is actively against the touchpad and the section of rope between the robot and the davit is under tension.

Design your winch so it unreels (slowly) when the match is over.

[Levi_Madden]

So according to the rules, velcro may be considered a rope as it’s flexible and non metallic. Is this correct?

Just remember that G15-C states you can not attach to the field using hook and loop (AKA velcro). When you add your own rope, it becomes part of the field, therefor, you could use velcro as a rope, but you can not attach to it.

[icomella]

Yes, but the loops can only be 10" in diameter.

[Maxwellfire]

I was thinking about something like this for our team. There’s no minimum diameter listed, and I think that coiling a smaller rope would be easier. (Wrapping the field rope around a pulley seemed impossible). The only question is whether you can tie a large enough knot in the end to satisfy the > 1" requirement at the top.

[engunneer]

I was thinking about something like this for our team. There’s no minimum diameter listed, and I think that coiling a smaller rope would be easier. (Wrapping the field rope around a pulley seemed impossible). The only question is whether you can tie a large enough knot in the end to satisfy the > 1" requirement at the top.

getting a 1" know is just a matter of a bigger more complicated knot (I suggest a monkey fist in the extreme case).

I’m not sure i would trust a robot to just a 325 lb tensile strength. a robot will be a pretty dynamic load, and the rating goes down quickly if there is any damage. Test test test!

[Riri700]

Does this mean it can be looped also?

The rule book states that you can use a loop. But it cant be rigid? it needs to be loose. So if pulled on it tightens. And it cannot be any larger than 10" in diameter.

This can be found on page 100 for specifics.

[COL_Woodchuck]

Just remember that G15-C states you can not attach to the field using hook and loop (AKA velcro). When you add your own rope, it becomes part of the field, therefor, you could use velcro as a rope, but you can not attach to it.

I believe the rules in G15 make an exception on the rope so a velcro rope of “loop” and a winch drum with “hooks” would be allowed.

From G15:
Items A-G exclude ROPES installed on an ALLIANCE’S AIRSHIP.
A. Grabbing
B. Grasping
C. Attaching to (including the use of hook-and-loop tape against the FIELD carpet)
D. Grappling
E. Hanging
F. Deforming
G. Becoming entangled

[carpedav000]

Just remember that G15-C states you can not attach to the field using hook and loop (AKA velcro). When you add your own rope, it becomes part of the field, therefor, you could use velcro as a rope, but you can not attach to it.

I believe this only applies if you use the velcro to strategically hold the rope in place by attatching it to the carpet.

[Kevin_Sevcik]

The rule book states that you can use a loop. But it cant be rigid? it needs to be loose. So if pulled on it tightens. And it cannot be any larger than 10" in diameter.

This can be found on page 100 for specifics.

The field drawing doesn’t show anything nice about the 90 degree turn the rope makes in the davit. It’s shown as a square tube butted against sheet steel bent into a channel, with some weld. I wouldn’t expect it to be sharp, but it’s not going to be nicely rounded either. And a smaller rope is much more likely to swing and scrape across the edge than a larger one.