How to Get Your FRC Robot Under the Weight Limit (Without Weakening It)

You cut weight by finding where the mass actually is before you touch a saw, not by hacking away at whatever's easiest to reach. Most teams that go over spend the last week of build season trimming the wrong parts under pressure: thinning bumper padding, drilling holes in a plate that's already thin enough, downsizing wire that's already at the legal minimum. None of that is where the pounds are. The pounds are almost always in the drivetrain, in duplicated hardware, and in parts that were sized "to be safe" instead of sized to the actual load. This is how to find that mass, cut it without weakening the robot, and never get surprised by a scale again.

The budget you're actually working with#

Per the 2026 FRC Inspection Checklist, the numbers you're designing against are:

That 115 lb figure has held steady across both the 2025 and 2026 manuals even while the size box shrank dramatically between those two seasons, but treat that as a coincidence, not a promise. FIRST revises Section 8 every year and sometimes mid-season through Team Updates. Confirm R103 fresh at kickoff every year rather than assuming this article's number. For the full rundown on frame perimeter, extension, and bumper construction, see FRC Robot Rules: Weight, Size, and Bumper Limits.

Where the mass really lives#

Before you cut anything, know that the drivetrain eats the biggest single share of most robots' weight, and it does it in ways that are easy to underestimate. Modern brushless motors alone aren't heavy individually, current published weights are REV's NEO at 0.938 lb and NEO Vortex at 0.99 lb, and CTRE's Kraken X44 with integrated Talon FX at 0.75 lb versus the Kraken X60 at 1.2 lb. But that's before gearboxes, wheels, and modules. A single WCP Swerve X2 module in a standard tube-mount configuration runs 3.25 to 4.3 lb by itself, with no motors attached, depending on gear material and mount style. Multiply that by four modules and you're at 13 to 17 lb before a single Kraken or NEO goes on, and before the tube frame around it.

One thing you can't design your way around: the inspection checklist caps you at four propulsion motors (R501, R502), so the drivetrain motor count is a fixed ceiling. Your lever there is gearbox and module choice, not motor count. Above the drivetrain is where uncontrolled weight creeps in, extra structure on an elevator or arm, oversized brackets on an intake, a second gearbox "just in case" on a shooter.

Find the mass before you cut it#

You can't lighten what you haven't measured. Set material properties correctly on every CAD part (a part left as a placeholder material will report a garbage mass), and pull mass properties as you go rather than after the fact. If your team CADs in Onshape, see our Onshape tutorial for the workflow. Then close the loop: weigh the first few real parts against what CAD predicted for them. CAD estimates run light because they miss fasteners, wire, paint, adhesive, and stock tolerance, so use that early gap to set a fudge factor for the rest of the season instead of discovering it at ship week.

Lightening that doesn't weaken#

The good cuts change material or sizing, not geometry, so the mechanism keeps its designed strength.

• Swap material where the vendor already offers the option. WCP sells the Swerve X2 with steel or aluminum internal gears at the same dimensions, and the aluminum-gear version saves roughly half a pound per module, about 2 lb across a four-module swerve for zero redesign. For custom plates, our manufacturing and fabrication guide covers when 7075-T6 is worth its cost over 6061-T6: only on highly loaded, thin parts like swerve forks or elevator carriages, since 7075 costs more and isn't weldable.
• Right-size the motor to the load instead of defaulting to the biggest one. A Kraken X44 at 0.75 lb versus a Kraken X60 at 1.2 lb saves 0.45 lb per motor on a mechanism that doesn't need X60 torque, and that adds up fast across an intake, a climber, and a wrist. See FRC Motors Compared for sizing each mechanism against its actual torque and speed requirement.
• Drop to a thinner tube gauge on secondary structure. AndyMark sells the same 2x1 box tube profile in both a 1/16 in and a 1/8 in wall. Wall thickness roughly sets a thin tube's weight per foot, so a rail that isn't carrying your heaviest load doesn't need the thick-wall stock your primary chassis rails do.
• Pocket plates from the middle, not the edges. Remove material from the low-stress interior of a panel and leave solid material around bolt holes, bearing bores, and mounting edges. A rule of thumb that comes up often in Chief Delphi's pocketing threads is to leave roughly as much solid material around a hole as the hole itself takes up, more at any point that also carries a bolt preload. Test a pocketed gearbox plate or swerve mounting plate before you commit to it across four modules.

What to leave alone#

Some parts aren't worth the pounds they'd save.

• Bumpers. They're excluded from your 115 lb base weight entirely and live under their own 135 lb combined cap, so thinning the padding or backing doesn't even touch your R103 number, it just risks an inspection fail and leaves your own robot with less protection in a collision.
• Wire gauge. The current inspection checklist sets hard minimums, 6 AWG from battery to main breaker to the power distribution board, 12 AWG on 40A breakers, 14 AWG on 30A, 18 AWG on 20A. Going below the legal gauge to save a few ounces of copper is both an inspection failure and a fire risk from voltage drop and heat. See our wiring guide for the full table, and confirm the current-season minimums since electrical rules do get revised too.
• Bearing bores and mounting bosses. These need to stay at full section for the press fit or bolt preload to hold. Pocket around them, never through them.
• Primary chassis rails. The frame members that take contact loads from defense and collisions are the wrong place to drop to thin-wall tube. Spend that cut on brackets and covers instead. If you're weighing drivetrain choices generally, FRC Swerve Modules Compared breaks down weight alongside cost and performance for the major swerve options.

Track weight from week one#

Don't wait for a competition scale to tell you where you stand.

• Keep a running weight spreadsheet by subsystem starting at kickoff, and update it weekly from CAD mass properties, not just at the end of a subsystem's build.
• Weigh subassemblies as they come off the CNC or out of the box on a cheap bench or luggage scale, and weigh the whole robot on a real scale well before your ship or bag date, not the night before.
• Set an internal weight-check milestone partway through build season, a date where the team stops and compares the running total to the budget, so decisions get made with weeks left instead of hours.
• Hold back a few pounds of margin deliberately for the additions that always show up late: a camera mount, a second battery bracket, competition-only wiring. Spending your entire 115 lb on the base structure guarantees a scramble when those show up.

If you're within a couple pounds of the limit the week before your event, the right move is pulling a plate you don't strictly need, switching one bracket to thinner stock, or cutting a redundant gusset, not thinning the bumpers or downsizing wire below the legal minimum. Those are the moves that get you under weight and still let the robot survive a match.