“You Had One Job”, Bot

Only a Human would understand the pithy sarcasm in “You had one job”. When [tterev3]’s RopeBot the Robot became sentient and asked “What is my purpose?”, [tterev3] had to lay it out for him quite bluntly – “You cut the rope”. He designed RopeBot (YouTube video embedded below) for one job only – single mission, single use.

A couple of years back, [tterev3] had put up some thick ropes for a low ropes course in his backyard. Over time, the trees grew up, and the ropes became embedded in the tree trunks. Instead of risking his own life and limbs to try cutting them down, he designed RopeBot to do the job for him. It’s built from scavenged electronics and custom 3D printed parts. A geared motor driving a large cogged pulley helped by two smaller, idler wheels helps the bot to scurry up and down the rope. A second geared motor drives a cam reciprocating mechanism, similar to industrial metal cutting saws. A common utility knife is the business end of the bot, helping slice through the rope. A radio receiver and controller is the brains of the bot which drives the two motors through a motor driver board. The remote controller, assembled on a piece of foam, has three switches for Up, Down and Cut. Everything is held together on the 3D printed frame and tied down with a generous use of zip ties, with rubber bands providing spring tension where needed. When the rope has been cut, the RopeBot comes down for a smashing end. It might not look fancy, but it gets the job done. We spy some real ball bearings on the three pulleys meaning [tterev3] didn’t skimp on good design just because it’s a disposable robot. Obviously, he spent a fair amount of time and effort in designing RopeBot.

Once the job is done, most of the electronics and hardware can be recovered and used again while the 3D printed parts could be recycled, making this a really cost-effective way of handling the problem. Like the Disposable Drones we covered earlier, these kind of “use and discard” robots not only make life easier for Humans, but also ensure low economic and ecological impact.

29 thoughts on ““You Had One Job”, Bot

    1. I doubt it.

      You have to factor in the weight of the rope.

      Also parachutes need time to fully open then further time to actually slow down. At that height it might hit the ground first.

      And… parachutes like free, open spaces. Each time it bumps into the tree it will deform. Actually, being so close, if it is big enough to do the job it will never be able to fully open in the first place so it won’t do the job.

      But… there is a much simpler way to save the bot!!!

      Just throw another rope through the crook of the tree with a weight (big nut) so that the thrown end will come all the way down. (really a heavy duty string is all you need) If you have a hard time getting it up there then do what hams do. Get a wire antenna launcher (fishing reel attached to a slingshot) Remove your weight and attach it to the bot. As the bot climbs pull the end that you kept so as to eliminate most but not all of the slack.

      When the robot falls your string will catch it! Slowly lower the robot back to the ground. Untie your bot and pull the string out of the tree before the tree grows around it too.

    2. If he just loaded the bot onto the rope with the blade below the gripping pulley, the robot would not fall when the rope was cut. He could then arrange some kind of net beneath the bot, and have it climb down until it runs out of rope and falls into the net.

    1. Since this is titled ““You Had One Job”, Bot” and the job was done perfectly you (@REN) are the only one failing this week. Perhaps you missed the video above where a radio remote controlled, one task, disposable robot climbed up in a tree and cut a rope…Actually two ropes so it was 200% more effective than originally designed.

    1. Lol! I love Metcals too! I got to use one in undergrad during an internship. After getting back, convinced my research lab to get one. The response was so great that by the end of the semester, we had three more (thanks to people fighting over using it).

      I just managed to get my own of Ebay. It arrived yesterday, and works great. I need a stand for it, since it didn’t come with one, and I’m thinking about throwing to some neodymiums on it to see if I can emulate the auto-sleep stands. Some comments on EEVBlog forums seem to indicate that the “sleep” function comes from magnetically quenching the tip, which serves to effectively lower the curie point and thereby lower the temperature.

      1. I’ve been using Metcals since the first year they came out, and never looked back. Over the years I’ve acquired a few of them, along with a massive selection of tips. From about 1998 through 2005 I bought and sold 40 or 50 of them, plus Dog knows how many tips. I have a few of the esoteric tips that require two wands, used for removing 144-pin QLFPs and such. Also several pairs of the tweezers, which are invaluable.

        While the original power supply had a set screw that could be turned in or out to enable or disable an inactivity timer, I wasn’t aware of the WS1 auto-sleep stand. That’s pretty trick, I’ll have to see if I can get ahold of one of those on the cheap.

        1. What’s your favorite tip? I’m fairly partial to the STTC-137p. I’ve found that it’s beefy enough to do most through-hole parts (including SMA and N RF connectors), and small enough to manage even 0403 SMD parts. The only issue I ran into was using some older pin headers, which used a soft thermoplastic body that deformed if you soldered pins straight through. But by skipping two pins or jumping from end to end between pins would give it enough time to cool down.

          How useful are the tweezers? What do you mainly use them for? I’ve seen them around, and my last place had one of them, but I can’t remember anyone using them in nearly three years. That said however, we were mostly troubleshooting and maintaining 80-90s era tech, so we rarely saw much SMD stuff.

          I was entirely unaware of the inactivity set screw. I might have to see if there is one on mine. I bought an RFG-30 (STSS-02), so it might have it :)

          Supposedly you can stick a couple of strong magnets to the original stands to mimic the WS1. Check the EEVBlog post here: http://www.eevblog.com/forum/reviews/what-metcal/msg442573/#msg442573

          1. Favorite tips are STTC-137 (mostly SMT), STTC-040 (through-hole, small wires), STTC-117 (big wires, anything requiring a LOT of heat), and the SMTC-0167 for drag soldering.

            I don’t use the tweezers a lot, but when it comes to removing SMT resistors, capacitors, and other parts between 0402 and 2012, they’re far quicker than anything else. Typically I have a fine pair of tips in them, but occasionally load the .25″ or .50″ wide tips to remove SOIC parts up to 20 pins.

            One of the other things I’ve acquired is an inline power meter. It’s not the PS-900, which has the DIN-7 connector, rather this has a connector for the RM3-E wand, and a 4″ cable that attaches to the base. I can’t recall the part number on it, but I can’t even find a picture on Google. It was useful for testing power supplies, and I remember the sales guys using it as part of their demo.

            Incidentally, for those following along and possibly considering a Metcal, do NOT buy into the SP-200 line. Nothing in that that series is compatible with the 500 series. I’m not even sure why they came out with that, unless it was intended to be a lower entry cost into the Metcal line.

            And what I’d really like to have is a Metcal hot air rework station, along the lines of the MRS-1100a, but I have yet to find a used one that’s affordable.

        2. Quick question – is there much gained between the 470kHz and 13.56MHz versions?

          I’ve got a new MHz one at work, but can’t afford to buy one for home. Thinking of grabbing a much more budget-friendly Thermaltronics 470kHz model…

          1. recently asked that question on Reddit, and the consensus was that no, there isn’t much of a difference. A marginal lag (another couple of seconds more than the 14MHz units), and on some models, a slightly lower power output.

            However, you can generally find the older Metcals (MX500s and RFG-30s) for under $150. I recently snagged a deal at $70 shipped for an RFG-30 with wand and tip.

            Metcals are built like tanks, especially since the towers or stations are basically just really basic RF tone generators. The tip cartridge does all the temp regulation. With that aspect, replacing the tip essentially gives you a nearly new iron.

            Given that, I really recommend just getting a used Metcal over the cost of Thermaltronics unit. They haven’t been around long enough to really tell how long they’ll last.

          2. @ajford – thanks for the info. Sadly it seems used Metcal stations here in Australia are rare (unless there’s a marketplace I don’t know about). I can import a used MX500 from the USA for about the same price as a new Thermaltronics (470kHz model), but then I’d have to add a 230:110 step-down transformer as well.

            At the moment my leading contenders are: Thermaltronics 470kHz for AUD$320, or possibly-fake ebay Hakko FX951 for $385 (reputable suppliers for Hakko FX951 are over $450, it’s ridiculous)…

          3. Yeah, importing to Australia is definitely a tricky proposition.

            You wouldn’t however need a step down. There is apparently an internal jumper in the mx-500 that can be moved to switch it to 220vac. See https://www.eevblog.com/forum/reviews/metcal-mx500-us-version-in-europe/

            If I were traveling to the land of drop bears and death any time soon I’d offer to be a pack mule, but I don’t have any plans.

            I did look into the Thermaltronics units, and I did find pretty positive reviews, so I hope that turns out well for you. Personally, at the same price point, if probably go for a used mx-500 over a new Thermaltronics, but that’s just me.

            Good luck with soldering irons!

  1. Wonder if an under-inflated water wing or similar ‘bubble-like’ item (heck, even some bubble-wrap) around the outside could make it more reusable. Assuming one has need to use it more than a couple times.

  2. Am I the only one that would try to scare little kids with it by telling them it was made for fingers? “The worse you are, the further down your finger it will crawl!” You only need to demonstrate with the rope ONE TIME!

  3. This is another proof that there are no “single mission” designs. It will always be reused, if it is not destroyed at first time. If you need it once, you’ll need it again.

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