Grappling hook?

[Al Skierkiewicz]

Originally Posted by bobmonkey836

after all, mountain climbers+ gear tend to be well over 120 lbs, and those ropes will easily hold the weight.

Look up spectra cable and be shocked and awed. We have used it for many years including last year.

[viperred396]

Originally Posted by bobmonkey836

it's very plausible. if you could get the accuracy, you should have the strength pretty easily after that. after all, mountain climbers+ gear tend to be well over 120 lbs, and those ropes will easily hold the weight.

I remember reading somewhere that after hanging a large weight from one of those ropes you shouldn't use them again because they might break. even if it hold during testing and the practice matches but then it might break in the qualifiers causing you to lost

[elmer_fud]

Originally Posted by viperred396

I remember reading somewhere that after hanging a large weight from one of those ropes you shouldn't use them again because they might break. even if it hold during testing and the practice matches but then it might break in the qualifiers causing you to lost

I think climbing rope will be overkill. A climbing rope will require something over 1000 pounds to break. Some parachute cord (1/8 in rope) has a breaking strength of 300 lbs but you would likely break this using it with a 150 lb robot. I think something in the area of 3/8 inch rope would work well

With climbing rope you are not supposed to use it again after a hard fall ( several feet) because it is weakened. Putting 150 lbs on it repeatedly will not hurt the rope.

references
parachute cord http://www.rei.com/product/784296

climbing rope http://www.backcountry.com/outdoorge.../EDL0009M.html (9kn is about 2000 lbf)

[Dick Linn]

Originally Posted by roborat

I saw several bots hang in 04 using hooks but the all had some type of arm extend up with hook on end to catch the bar and the hook and cable were velcroed so they would release from the arm and winch up the bots. Only purpose of the arm was to place the hook.

Team 975 used a telescoping tube made from nested PCV pipes. There were flat-wound clock springs to extend the arm segments and a small steel cable/winch to control extension and lift, and a hook on the end that was loosely attached. It worked fairly well. In one match at the VCU regional, all four robots were hanging from the bar. That year's robot was unofficially named "hooker".

It's the lowest one in the foreground. (Check out the officials in the background - everyone went wild.)

http://www.chiefdelphi.com/forums/at...d=126348704 6

[Joey P]

Yea I don't think that the Grappling Hook would be such a good idea for this game, but in general it is a good thought. Maybe it can be used in a game in the next few years but I wouldn't for this because it would be dangerous. Plus, what if your hook missed the pole and it latched onto the ball return rack, It could destroy the return rack, which would not be good for your team or the actual competition.

[Edoc'sil]

Originally Posted by Sean Raia

I think our team is actually going with a scissor lift mechanism with hooks on the top. we want to be able to go under the tunnel. I just thought the grappling hook was a neat idea for discussion, and im from what i read its possible and legal if it doesn't go outside the dimensions.

I would be wary of this idea, w tried to do this a few years back lifting just a few pounds and ours totally failed. If you do decide to do this just consider that the lower the lift gets the worse the mecanical disadvantage gets.

[AdamHeard]

Shooting a grappling hook might be unreliable just from a rules standpoint; you can't exceed 90" tall, and the bar is 84" tall, that's a very small margin for error on a shot.

[Callbt]

Can you use a "pole climber" to place the hook at top and then winch the cable/rope back in?

[EricH]

Originally Posted by Callbt

Can you use a "pole climber" to place the hook at top and then winch the cable/rope back in?

Nothing against it.

However, there is one thing that a LOT of robots had in common in 2004: If, for some reason, their hook came off it's pole, it was impossible, or close to it, for them to try again. This led to a number of hooks dragging on the floor. I remember one match where a team's "pole climber" hook got stuck in my team's lift's lightening holes, which were admittedly rather big, but it was just bad luck there. They'd managed to drop the hook, too, so they were stuck for the duration of the match.

My team never had to worry about that; our policy of "All deployables shall be retractable" plus a key design feature we had had led us to have a very solidly attached single-tooth hook fixed to the top of our lift, so no deploying that one...

[Brandon_L]

Originally Posted by Mr_I

Case in point, Team 811:

The black pole on the right telescoped out ~15 feet to put the grappling hook over the 10' chin-up bar, and then a window motor (legal then) pulled Red Streak II into the air v-e-r-y s-l-o-w-l-y .

Window motors arn't legal this year?

[EricH]

Originally Posted by Brandon_L

Window motors arn't legal this year?

Sometimes they are, sometimes they aren't. This year, there happen to be 4 in the KOP, 2 LH and 2 RH. That means that those 4 (or exact replacements) are legal, but any others that are on the robot are not.

[Mr_I]

Originally Posted by Brandon_L

Window motors arn't legal this year?

My apologies! I meant to say "van door motor". (Too many details from too many years ...)

[Andrew.Jensen]

We thought about this idea, but we realized it was impractical for a few reasons. One is that the precision needed to latch onto that tower without going past the hight limit is ridiculous. You'd have to time to hook and measure it so it reaches the maximum of its arc about three inches above the bar. Also, the reeling in doesn't seem so practical, especially because the grappling hook might break. Finally, I think FIRST does not allow shooting things, or at the least they frown on it. Well, good luck with your idea if you use it.