Spectrum 3847 | Build Blog 2023

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.


How inflated are the cubes in the shooting video? They look like they might be over filled to me but I am not sure.

We measured them to be close to correct but haven’t made the sizing jig yet so they could be slightly large.

gear sprocket


Why not just do a fixed angle (but steeper) rather than having the elevator + slider? Wouldn’t it be easier? My team is considering it rn and I was wondering why you decided against it.


How about a scissor “arm”? Were thinking about having two horizontal standing scissors and rods holding the scissors together to reduce the overall swaying of the scissors.