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Gobble Squabble: Getting Started

Gobble Squabble: Getting Started

Welcome to the Gobble Squabble squad! This information is to help you get started. We will progressively publish more information to help you with planning and building your 1 lb (aka “Antweight” in the USA) combat robot for participation in this year’s Gobble Squabble event.With good cost and parts selection, you should be able to build your robot for $150 – $200. Even an expensive robot with many advanced features should cost less than $300. We will provide lots of information about choices and sources of components.

Big Rules:

  1. Be safe in building, testing and operating your robot. High-speed spinning weapons (if your robot has one) can be dangerous, so don’t test them around other people or pets. Wear safety glasses when testing the robot or using tools.
  2. Your robot cannot weigh more than 1 lb and 0 ounces, or 454 grams, in its final operational combat configuration. We will measure this at check-in at the event, and you will be required to remove parts of your robot until it weighs no more than this maximum. (Tip: robot weight is best measured on a digital kitchen scale.)
  3. Any weapon used by your robot (i.e., anything used to lift, clamp, hold, hit, cut, break or attack other robots in any manner) must be built primarily from 3D-printed plastic. Any surface of the weapon that will contact another robot must consist exclusively of 3D-printed plastic (e.g., if there are mounting screws inside the weapon, they must not be able to contact another robot in any way). *** Click here for guidance to help you get started with 3D design ***
    1. Exception: for 2019, a kitbot wedge will not be considered a weapon.
  4. The body (e.g., shell) of your robot should be built exclusively from 3D-printed plastic. Any surface of the body that will contact another robot must consist exclusively of 3D-printed plastic. Screws or other fasteners may be used inside the body or in ways that will avoid contact with other robots. *** Click here for guidance to help you get started with 3D design ***
    1. Exception: for 2019, use of kitbot bodies will be allowed. But, to be clear, kitbot weapons (example 1, example 2) will NOT be allowed in any case.
  5. The only 3D-printed plastics allowed for robots are plain PLA, ABS and PETG. To be clear, no additional fillers (like carbon fiber, glass fiber, wood or metal) are allowed in the filament used to print your robot body or weapon.
  6. Your robot must have a power shut-off device. Examples are small toggle switches, or the Fingertech Mini Power Switch. Check our design guides for options and ideas. (Tip: ensure this device cannot be engaged by another robot; if another robot shuts off your robot, they’ve won the match.)
  7. Other details can be found here. Note that only the “rolling” style of “1 lb Plastic” robots will be eligible to compete in the Gobble Squabble, with the exceptions listed above. Please feel free to contact us with any questions.

Robot Styles

Choosing the combat style of your robot will be one of the most important things you do as you prepare for the Gobble Squabble. It’s a good idea to choose your robot’s combat style before you select most of the components for the robot. Here are some insights to get you started:

  • Offense or Defense
    • Offense-oriented robots are the most “fun” but have the most design and build challenge because they have more parts and require more engineering trade-offs to stay within the maximum weight. Offense robots break more easily during combat because they tend to have have thinner plastic parts. But a well-designed carefully-built offense robot can cause real destructive damage to other robots.
    • Defense-oriented robots are easier to design and build, but usually offer less engineering challenge and therefore less potential learning for you. Defensive robots seldom win by knockout, but can win with driver skill, reliability (ability to run the full 3 minutes) and sometimes good luck. In the “good old days” defensive robots used to have an edge in winning percentage, but as parts and designs have improved, well-built offensive robots have caught up.
    • Some of the very-best combat robots have elements of both styles: offense to attack, and defense to withstand some damage and win the battle for the low-ground. These combinations can be difficult to master in your first designs, but can provide more challenge and learning if you’re interested.
  • Defensive Models
    • Wedge: this is basically a triangle profile on 2 wheels. The front edge of the triangle actually rides on the arena floor. Wedges are used to win the battle for the low-ground, and to get control of the opponent robot with less risk of being hit by its weapon.
    • Ram: this is a battering-ram on 2 or 4 wheels. It can be effective against spinning-weapons if designed and built well.
    • Pusher: this style combines 4 wheels with heavy armor to withstand damage and control the other robot by pushing it around. Yes, with good engineering you can get 4 motors and wheels into an Antweight robot!
  • Offensive Models
    • Flipper: embed a lifting element into a wedge design and you have a flipper. Usually a small servo drives the lifter. With some clever engineering, the lifter has enough lift (both power and distance) to flip some opponent robots on their back or side.
    • Vertical Spinner or Drum Spinner: in this style, a weapon is attached to the front of the robot and turned at high speed in a direction perpendicular to the floor, typically 1000s of rpm. This style requires integration of a brushless motor and control system. (Caution: this style of robot requires special care to either test or use. An unbalanced weapon can actually vibrate itself and/or other parts of the robot to pieces, so designing and building the weapon to have perfect balance is required.)
    • Horizontal Spinner: similar in concepts and cautions as the “vertical spinner”, except the weapon rotates in a direction parallel to the floor.

This picture shows multiple examples of offense-oriented robots: (left) a vertical spinner with the weapon driven by a brushless motor; (middle) a simple flipper (the white panel is a lifter); and (right) a complex flipper (the middle wedge section is a lifter). All comply with the rules for the Gobble Squabble. Hint: 2 of the robot designs shown above are based on the shell design detailed in the 3D design posts. *** Design your own robot and 3D print it — here are tips and guidance to get you started ***.

Selecting The Parts

Here’s a summary list of the major parts your robot will need to function and compete. More information on selection criteria and sources is published in other posts.

  • Radio transmitter and receiver. We highly recommend spread-spectrum programmable models. This will be the most expensive component of your robot. *** More selection and sourcing details are provided here ***.
  • Drive motors: you will need 2 to 4 of these, plus spares if you want to recover from damage. These will be smaller than you think to stay within the 1 lb weight limit, and should range from 250 rpm (if you want good control) to 1000 rpm (if you want extreme speed and think you have excellent driving skills). Buy 6 volt DC motors if you plan to use 2S (7.4 volt) LIPO batteries or 9V alkaline batteries (not recommended), or 12 volt DC motors if you plan to use 3S (11.1 volt) LIPO batteries. *** Click here for full details and design guides ***.
  • Battery: you will need 1 of these, and perhaps 1 spare. We recommend 3S LIPO batteries with a capacity of 480 mAH if you use a spinning weapon; you can use a smaller (lower mAH rating) battery otherwise, if desired. 3S LIPO batteries enable you to use 12 volt motors and parts; for somewhat lower cost, you can use 2S batteries and power 6 volt motors. WARNING: NEVER cut or modify any of the leads to a LIPO battery; they should always be used in factory-original condition. DO NOT plug the LIPO battery into your robot wiring until all of the wiring is 100% complete with no bare metal exposed anywhere. If you don’t want to manage these risks or want a lower cost solution, you can use 9V alkaline batteries with 6 volt motors. *** Click here for full details and design guides ***
  • Battery charger, matched to your selected battery system (unless you use 9V alkaline batteries, which don’t need a charger). *** Click here for recommendations, at the bottom of the page ***
  • Wheels: typically these are of diameters of 2 inches or less, but larger wheels can provide more speed (but also have serious control issues). Wheels can be purchased from COTS sources, or you can make them yourself from foam or 3D printing. *** More selection and sourcing details are provided here ***.
  • Weapon motors: these are usually brushless motors or servos. If you plan to use a brushless motor in your robot, we recommend you use a 3S LIPO battery for best results and greater impact power. *** More selection and sourcing details are provided here, in the section “Weapon Motors” ***.
  • Motor speed controllers: combined with the radio receiver, these devices vary the power to the drive and weapon motors to enable you to control and operate the robot. Servos can connect directly to the receiver. Almost always drive motors required brushed DC motor controllers (which are becoming more difficult to find), and brushless weapon motors required brushless motor controllers. Good choices here will help you build a better robot at less cost. *** More selection and sourcing details are provided here ***.
  • Mechanical components and fasteners: to hold the robot together and make your weapons and mechanisms strong and robust. *** More selection and sourcing details are provided here ***
  • Wiring, connectors and electronic parts: miscellaneous parts to complete the control circuits and connect everything together. *** More selection and sourcing details are provided here ***, and *** full details on how to connect everything together are provided here ***
  • 3D Printing filament: typically, a full 1 kg roll can print at least 10 full Antweight robot shells plus required parts. So 1 roll should cover all of your learning and the final product, and still provide some extra to help your friends. Refer to the 3D Design post for more information and sources of 3DP filament.

Have Fun!

The main point of the Gobble Squabble is to have fun while learning important and useful design and engineering skills. Learn a lot, refer to these guides and other great materials on the Internet, and contact us if you have questions.

This information is original work by Techno Chaos and is published under the terms of Creative Common license mode Attribution-NonCommercial-ShareAlike (CC BY-NC-SA).