RobotRobot: New page: weight rules (SPARC, NHRL), weight budgets, saving weight, making weight at events

2026-10-17T06:46:25Z

New page: weight rules (SPARC, NHRL), weight budgets, saving weight, making weight at events

New page

Every combat robot is a balancing act between weapon, armor, drive and electronics, all within a strict weight limit. Being even slightly overweight can cost you a match or keep you out of an event, while every gram you save can go into something useful. This page covers planning a weight budget, saving weight, and making weight at events. For the weight classes themselves, see '''[[RobotClasses|Robot Classes]]'''.

__TOC__

==The rules==
* '''Weight classes''' are set by each event; the SPARC names and limits are listed in the '''[[SPARC Tournament Procedures]]'''. Robots that walk, shuffle or use unusual drives can weigh more (see '''[[Multibots, Walkers and Shufflers]]''').
* '''Re-weighs:''' under SPARC rules, officials can re-weigh a robot at any time. A robot less than 5% over must get under weight before its next match; more than 5% over, and it forfeits its previous match too. Repeat offenders can be disqualified.[https://sparc.tools/SPARC%20Tournament%20Procedures%20v1.2.pdf]
* '''NHRL''' uses its own rules: being up to 2.5 oz over earns a penalty point and a chance to fix it, while anything more is an immediate loss by TKO.[https://wiki.nhrl.io/wiki/index.php?title=NHRL_Rules]
* Weigh your robot the way it will fight: with its battery, in its heaviest configuration (with the heaviest weapon option or armor set), and with any removable link in place. Check whether your event weighs the weapon lock.

==Plan a weight budget==
Before you build, write down the weight of every part and add it up. A spreadsheet works well, or your '''[[CAD for Combat Robots|CAD]]''' software can calculate it from the materials you assign.
* Start with the parts you're buying (motors, ESCs, battery, receiver, wheels) – their weights are known.
* Decide how much weight to give the weapon, armor and frame. There's no fixed rule: a spinner might put a large share of its weight into the weapon, while a wedge or control robot might put more into drive and armor.
* '''Leave a margin''' for wires, screws, glue, heat-shrink and the things you'll inevitably add later. Small robots in particular gain weight from hardware and wiring faster than you'd expect.
* Aim to finish a little under the limit, so you have room for repairs and changes at the event.

==Saving weight==
* '''Choose materials by weight, not thickness''' – compare at equal weight (see '''[[Armor and Materials]]''').
* '''Size the battery to what you need.''' Calculators like the '''[https://runamok.tech/RunAmok/TTT_example.html Tentacle torque and amp-hour calculator]''' help you avoid carrying more battery than you'll use (see '''[[Batteries]]''').
* '''Remove material where it isn't needed''': pocket or hollow out plates and printed parts, and use less infill or fewer walls in 3D printed parts where they aren't loaded (see '''[[3D Printing]]''').
* '''Shorten wires''' and use appropriately sized ones (see '''[[Wiring and Soldering]]''').
* '''Use lighter fasteners''' where loads are low: shorter screws, fewer screws, or titanium or aluminum hardware (see '''[[Fasteners and Hardware]]''').
* '''Combine parts''': a frame part that also mounts the motors, or a weapon that also self-rights, saves weight twice.
* Don't save weight in the places that take hits – a lighter robot that breaks isn't a better robot.

==Making weight at events==
* '''Bring a scale''' that can weigh your whole robot, and check it against the event's scale if you can.
* Weigh again after every repair or change – replacement parts often weigh more than the originals (see '''[[Pit Kit and Event Checklist]]''').
* Have a plan for quick weight savings if you're over: a lighter wedge or armor panel, a smaller battery, or holes you can drill.
* Some events allow extras, such as a small camera, above the weight limit – check the event's rules (SPARC's optional camera rule allows it if officials approve).

==See also==
* '''[[RobotClasses|Robot Classes]]'''
* '''[[Drive Systems]]''' – how heavy drive motors usually are
* '''[[Spinner Design]]''' – how weapon weight affects energy

Weight Management - Revision history

RobotRobot: New page: weight rules (SPARC, NHRL), weight budgets, saving weight, making weight at events