FRC 4481 Team Rembrandts 2020 Build Thread

Have you tried with the whole revolver tilted on an angle forward toward the intake? That might help the balls settle into their slots quicker. Also might make it get jammed more often :stuck_out_tongue:

Anyone else satisfied by the sound of that shooter???


The angle on the test setup was 15 degrees.


Have you done any tests on the WoD without any pockets? Similar to what you see a couple glimpses of in 708’s week 2 video?


I’m not sure if this would actually help with jamming. Additional benefit of the pockets would be already spacing out the shots going into the shooter column too.


May I ask what is your intake roller made of?

It is a polyurethane (rubber) tubing from McMaster. We use the 1-1/4" Outer diameter, 1/2" Inner diameter, 40A (article nr.: 87235K82). A 1/2” hex shaft fits perfectly with a tight fit. We used it in our 2016 robot for the first time, but afterwards almost every year. It is great for intake mechanism!


Just wanted to say it’s the 1/2" ID that is important. You can use different OD and change the geometry to get similar performance. That tube you linked is pretty expensive and there are alternatives.

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Week 2 Recap Video:
2 weeks down, another 2 to go! We’d like to have our robot up and running within 2 weeks from now so we can start driver practice and software development.

The week 2 recap below shows the prototyping and current concepts we’re working on!

New week 3 update will be posted tonight!


Week 3 - Update 1

WoD - Wheel of Doom or Wheel of Death?

Monday during the team evening we’ve given the WoD concept once last try to succeed and if we weren’t happy enough by it’s performance we would move on to the different concept.

Anti Jam Code - 1 Powercell

Anti Jam Code - 5 Powercells

No Pockets + Omni

No Pockets + Brush

No Pockets + “Spinning” Omni

WoD Decision Time:

  • Does it work? - Yeah-kinda-ish

  • Do we like the performance? - Dumping 5 powercells can be tricky but intake a sequence of powercells is doable

  • Is it fast enough? - Full field cycle, yeah probably. In the clean up roll/close shots, probably not yet

  • Do we already have a shooter that can handle 5 balls in ~0.5 second? - Nope not really…

  • Are we confident enough we could design the final iteration now in order to have a working robot within a week from now? - Probably not

  • What other sub systems are depending on the WoD? - Intake & climbing heavily; powercell intaking over the bumper vs. raising it higher to roll/dump/fall in the WoD and fitting a shooter & climbing in the middle of the WoD will be difficult to package. Shooter and Control Panel are trivial in a way that the Control Panel system can be integrated somewhere in both concepts. And the shooter has a mounting point where a powercell will enter so should be able to fit on both concepts.

The WoD draws lots of attention and interest within the team. We’re in love with the concept but we don’t feel we are far enough in performance to use it for week 1. Since all other subsystems depend on the WoD so much we decided to go for a “safer/easier” concept route which will allow the team to keep working on subsystems.

The WoD will be continued by a couple students and mentors. We’d love to have it working at some point that it’s fast enough and we’re happy with it. It might end up on our robot for Detroit Worldchampionship :wink:

Current WoD ideas are to move the shooter away from the middle, creating space in the center for a smaller column/tower and to possibly mount the climber. The shooter could be on the back or above a powercell maybe and by slightly tilting the WoD the powercells will roll towards the back creating space in the front.

We noticed that dropping in 3-4 powercells is easy but getting the 5th in position is difficult. See current idea below:

To be continued…

We will be proceeding with the concept below:

General Features:

  • Pivoting intake - #254 2017 style:
    2 x 775pro 4:1, 2x 40mm (~1.6") OD dead axle rollers.

  • Storage - #6135 2020 style:
    3 x 3" wheels. Swappable between colson or compliant wheels to test. Wheels will have different ratios to make sure the wheel closest to the shooter hole will spin faster than the outer wheels. Storage slope of 15 degrees and 4" wheel to suck the powercell through the hole into the shooter

  • Shooter:
    Offset to the right of the robot. 2" OD AM Stealth 4" wide kicker drum > individually powered by a 775pro. Shooter drum will be 4" OD, fairlanes or AM Stealth wheels and a external flywheel eventually powered by 2 NEO's 1:1. 2 position hood with ~15 degree angle and ~60 degree angle > Wall shot and longer shots with varying RPM

  • Climber:
    Centered in the middle of the robot. 2 or 3 stage linear tube. Testing this weekend with 2 stage, string and spring/tubing concept. Similar as the #118 Everybot 2020. Eventually package it into a 3 stage arm with constant force springs winched through a custom neo gearbox and a ~ 25mm/1" drum.

  • Control Panel:
    Pivoting wheel which allows to be tucked down to driver through the trench. Rev color sensor from below

Other decisions:

  • If driving below the trench hurts the climbing capabilities and packaging they’re allowed to exceed the trench height for week 1. All other sub systems need to be designed to be able to drive underneath the trench.
  • Switching from 6 NEO Drivetrain to 4 Neo Drivetrain. With the compressor and Limelight plugged in the PDP we were cutting it very close on PDP slots. 4 Neo’s will be plenty of power and giving us the capabilities of adding a extra kicker motor for example.

That’s it basically in a nutshell.
The team has worked hard to CAD the entire robot in a couple days, hopefully have our prototypes up and running by this weekend to have a better and improved integrated version of the one pictured above.

I’ll post screenshots of the CAD once it’s ready. :+1:


Will you guys be powder coating again this year? Loved how clean your robot was at San Diego regional last year.

We’ve been annodizing since 2014, we did the entire robot from 2015 untill last year.
The company who partnered with us throughout the years has grown enormously.

In 2014-2015 we could walk in, drop of a box with sharpie letters: black and another with orange and pick it up the next day. Throughout the years their processes have become more and more digital and advanced plus an increasing amount of work on their end of course.

Last two seasons it delayed is a lot throughout build season, sometimes by 3-4 days/team meetings.

This year we’ve said we won’t be annodizing/powdercoating unless we have a partner who can run parts within 24 or max 48 hours.
It looks like we’ve found a local company that could do powder coating for us… Our biggest priority is performance and then esthetics. (Atleast that’s our new goal for 2020)

So if we’re confident enough with our robot at some point and still have time to powdercoat certain subsystems then we will. Otherwise probably not…


Quick question: is it necessary for the first colson wheel (the one closest to the omni in your setup) to touch the first power cell? Or would it be perfectly fine to just have the omni shoot the first power cell out and then have the colsons agitate the ball?

Also, how big was the prototype, length and width wise?

Good questions!

@Justin_Foss with the first proto it was designed such that the colson would hit the powercell before the omni did. Was that on purpose or as first attempt?

I’ll double check on the dimensions :wink:

This is what we’re planning on building today! Sheetmetal just got picked up and almost in the shop. Ready for assembly and hopefully some testing today as well :wink:

The shooter side plates are aluminium but made transparent for the screenshot. The side panels of the hopper will be polycarbonate sheets but not shown in the screenshot.

Side Note: This is just a functional prototype to test the direction we are heading towards. If we’re satisfied with the results this weekend we’ll start detailing.


any detail you can give on the climb mechanism? just a standard 2-stage pulley system or what?

how were you guys able to make the indexer spin?

For the climbing mechanism we made our own telescope system . For the first prototype the students designed a 2 stage climber where both tubes are guided trough eachother with a constant force spring. (dutch suplier)
Atm we’ve started with designing a 3 stage climber with a constant force spring and a control system integrated for the 3th stage so we can do trench.


Cad model is not completed, and proto not intact anymore. But we laser cut our own sprocket driven by a VP gearbox and chain.

What kind of shot range are you comfortable hitting consistently with the neos 1:1 and a 4" diameter roller in the shooter? Do you feel that 23 feet from the goal is plausible?