Spectrum 3847 | Build Blog 2023

Interesting, I’ve never felt the need for finer granularity in belt choice beyond a 5 tooth increment.


Fall Elevator Design

We also designed an elevator during the fall, like many many teams. Ours wasn’t designed specifically to be a model of how we could build a competition elevator in 2023 if needed. It was designed to experiment with a few different elevator ideas and be a useful training tool for robot assembly.

Onshape Link

This elevator can either be run in a cascade setup or, as modeled, set up so the first stage motor and the carriage are decoupled and can be controlled independently. This could let you have a starting position with the carriage at the top of the robot or allow for specific over-the-back designs. You can also gear each stage for different speeds/power. You could have a very fast carriage used for most of the scoring and a slower 1st stage used for climbing and some scoring.

The carriage is raised and lowered by a belt running from the bottom to the top of the 1st stage that isn’t modeled in the CAD and powered by a motor on the carriage. This design took some inspiration from 1114-2019 with the sprocket and chain on the front side of the elevator. This design is also inspired by 971-2019’s thin polycarb cable carrier method.



Priority List

We completed our initial priority list of tasks for the 2023 game.

Cones from the shelf or the floor.

From what we have seen, we are currently a lot lower ground pick of cones than many other teams. Here are a few reasons that we discussed today.

  1. The cones can’t easily roll much further than the wall when dropped onto the floor from the loading stations, so you don’t have much of a cycle distance advantage over taking it off of the shelf.
  2. Intaking the cones from the various orientations and positions against the walls will be very difficult. We don’t believe it will be faster than loading from the known positions on the shelf, especially with the possibility of vision-guided aiming at the loading station.
  3. The Human Player shelf is just a bit higher than the middle cone node, so you don’t need to raise or lower it to be able to place it on the midsection. And for the top, you only have to raise it about a foot and extend it about a foot more than the mid. Much easier than also needing to reach the floor with your cone mechanism.
  4. You can have a specific cube(ball) intake on the ground level and don’t have to potentially compromise your robot’s ability to intake cubes(balls) also to pick up cones rapidly.
  5. 15 scoring locations out of 27 can be cubes which is more than half.
  6. Each alliance has 27 cones, so if you drop one, you can always return and get another to fill the 12 required spots.
  7. Any dropped cones while attempting to score on a mid or top row will land in the bottom row. If you are strategic about when you score the bottom row, your mistakes may still count for points.

Potential Alliances composition at Districts and Worlds

Cube Intake and Launching Prototype


Robot Inspiration

  • 33 in 2012 - Stinger and other 2012 team’s bridge balance aids
  • 1678 in 2019 - Double robot lift for the end game (wouldn’t need to climb)
  • 148 - 2011 - 4 Bar Arm - Arms are potentially useful in this game
  • 1684 - 2019 - Separate intake from elevator scoring mechanism. Doing this for the cubes(balls) will give you a wider intake for picking up the cubes(balls) from the floor.
  • Tilted/Angled Elevators from 2018 - 2056, 1731, and a few other teams had slightly tilted elevators that let them reach out of the frame while extending up.

Game Comparisons

  • Logomotion - 2011 - tic tac toe near side
    • Driver training will be similar.
  • Rebound Rumble - 2012 - End Game
    • Balancing on the bridge
  • Steamworks - 2017 - Cycles and non-symmetric field
    • Autonomous and cycles will be different depending on which alliance you are.
  • DDSPBTBC - 2019 - Multi-Game Piece
    • Cubes roll like cargo, and cones behave like hatch panels.
  • Power Play (FTC) - 2022
    • Picking up Cones

Is a stinger type device legal this year? If you push a stinger down to balance the ramp, when you transpose your robot onto a flat floor you would be violating bumper rules.

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You are correct we have that on our list of things to Q&A and haven’t done any design work or put much thought into it yet.

To be more precise we are going to Q&A that if extensions that deploy below the robot that can’t support the weight of the robot will still be legal. For example, a robot with suspension could have bumpers that when measured from the bottom of the wheels when lifted off the ground are more than 7.5in but when placed on flat ground they collapse and bring the bumpers within the zone. A relatively weak stinger type mechanism could be deployed in a similar manner and not break the bumper zone rules.


Day 2

We began making some of our field elements and talking more about possible designs.

Robot Testing

What happens when a 2022 robot runs into a cube? Watch till the end

Squishing the cone test

Scoring the cube with Infrared

8515 can score the cube as well

Example Sketch

Robot Inspiration

1986 - 2012: Twin Tucking Tabs and Stingers
6800 - 2022: Arm on an elevator
1619 - 2018: Full width cube intake


The robot popped before the cube did!

I’m curious have you tried running over an upright cone on carpet? In a brief test yesterday pushing a robot into an upright cone on carpet the bottom of the cone really dug in and put up a lot of resistance. It seemed like getting beached on an upright cone wasn’t out of the realm of possibility.

We tried this and didn’t have any issues, we even tried driving into a sideways cone from all angles and didn’t encounter any problems whatsoever, just pushed the cone around (using swerve mk4i, 1.5" bumper height)


Is it just me or is the video for 8515 not working? it looks to just be an image for me.



Day 3: Cone Intake, robot sketch, and game manual notes

Pinch Roller Cone Intake

One of our students devised an elegant solution for a game object mechanism that deals with both balls and cones. The circles are tubes, and it intakes cones from the top. Here is a very early prototype:

Elevator + Slider

This is one of our favorite sketches of a robot that can reach the top cone-scoring location and do most of the top items on our priority list.

  • The Slanted Elevator allows you to reach further as you raise the carriage.
  • The slider lets you extend towards the mid and top rows.
  • We use the length of the cone to reduce the extension needed to reach the top cone locations.
  • The cone pinch intake doubles as a ball intake
  • A flywheel/roller would let us launch balls to score them quickly in auton.

New things in the manual

  • District points for playoffs are official, according to the manual.
    • The 5th/6th and 7th/8th placed alliances don’t receive any Advancement Points
    • The points for each team are awarded based on the percentage of your alliance’s match wins that your team played in. So for an alliance without a backup robot, everyone gets 100% of the ALLIANCE Advancement Points.
    • If a backup robot were to play 1 of 4 match wins for the alliance, they would receive 25% of the Advancement Points, and the team they replaced for that match would receive 75% of the Advancement Points.
  • Playoff tiebreakers are only Tech Fouls and not all fouls
    • This is a good improvement.
  • New Champs Division Names
    • We believe the Milstein division is honoring César Milstein, and the Johnson division is honoring Katherine Johnson, but we haven’t seen an announcement yet.
  • R304 Blue Box
    • It’s now explicitly written that “running a 3D printer or other automated manufacturing processes overnight producing ROBOT parts” is against the rules.

GDC looking at this in dismay. Friendship ended with cube, sphere-with-seams new best friend.

I love the simplicity of the intake concept! Really reminds me of some of the 2019 intakes that had a hatch mech mounted right above the cargo mech.


I’m having a bit of a rough time wrapping my head around this one, so just to clarify: this rule is specific to tournaments, but not during regular build season? Or does this apply to build season/outside of tournament dates?

Yes just during events, here is the rest of R304

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Are there any thoughts about you all doing a similar pivoting telescope as your 2018 robot?

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After 2018, we added a design rule to our list*.

Never build an “elevator on arm”: we 100% should have built a more standard elevator in 2018. We had many issues with the way we designed and built our “elevator on arm” mechanism. The arm joint, internal bearing setup, wire management, and chain run all caused us multiple problems throughout the season. We rarely needed or used the ability to intake from both sides of the robot. Also of note, we only did a single extension arm, a double (or triple) extending arm is even harder. Most of our discussions about that season are that we should never try that again. The vast majority of games can use an “arm on elevator” or “slider on elevator” structure and be easier to design, build, and control.

Compounding on that in modern FRC there aren’t many COTS options for Pink-style elevator on-arm mechanisms with powered extension and retraction. If you want to pivot around the middle of the arm as we did in 2018 you also have to fully design that clamping mount and joint as well.

* Examples of other items on the list
  • Don’t build ramp bots
  • Never build a scissor lift
  • Don’t use mecanum wheels to drive on the ground

All of these can be done well, Spectrum just isn’t likely to ever try.


Got it, those are all great points. My team was considering it but we were worried that it would take too long to get working right and that there could be lot of issues that could arise with it (you addressed most of them above).

I think there will definitely be some teams that do it this year, and if done right could be extremely effective, although probably pretty annoying to deal with and do maintenance on, especially since you would probably need a multistage telescope.

  • Never go in against a Sicilian when death is on the line

Does this mean the telescoping arm you made or any elevator that pivots? Our team’s current idea is to rotate an elevator and now I’m feeling like:


All of these rules have their exceptions, so it’s really up to you to decide if your design meets your team’s strategic requirements and is an effective use of your team’s resources.

Make a sketch with your robot and all the possible positions you believe the" elevator on arm" will need to be used in and then think about the motion paths it takes to get there. Does it reach all those places? Does it do it efficiently? Will it have other problems? Imagine it driving around doing all the game tasks, are there things you would be worried about? Like being too far away from your bumpers while ground intaking, or when you drive will your center gravity be higher than other options? If you run your mechanism into the Human Player station or another robot at full speed what do you think will break first? Can you ensure that you won’t accidentally extend past the frame perimeter while in an opponent’s loading zone or community?

Also make sure you fully understand the mechanics of the mechanism, the bearing setup, and power transfer for these types of mechanisms can get complicated and be prone to failure if not planned well.