Spectrum 3847 - Build Blog 2020

So I have observed this type of robot starting to become the meta. We are very similar, just short and I have seen others as well. Will this become more true as everyones robots evolve with competition?

I wouldn’t really say:

If anything, people have been around FIRST long enough, or people have paid attention to the past 20 years of FIRST history, to begin to see patterns, and re-use sub-components that work for indvidual years.

That, combined with:

  • The advancement of Robot in 3 Days
  • The #openalliance
  • Everybot and minimal competitive concept designs
  • General robot rules haven’t changed significantly in 10 years
  • Greyt products

All of these things lead to similarly shaped robots. Which isn’t a problem! Leads to cooler control schemes and system integration (ball tracking that Spectrum is implementing, more time for testing and implementing buddy climbs, etc.)

I can guarantee you that something will pop up in the season that will become the “meta” that most teams haven’t discovered yet. Think back to 2012 - the “stinger”


I just found that the ratcheting wrench is discontinued at Grainger. There are similar wrenches available at Lowes and Home Depot at a reasonable price.

Got ours on Amazon for less than $8 with prime shipping.

Day 45 (plus a few of the previous days)

Comp Robot is beginning to come together.


Now with more polycarbonate

Shooter Hood

Printed and laser cut hood.

Camera Mounts are progressing

Buddy Climb Mechanism

The deployment mechanism is progressing.

More photos and videos can be found in our gallery.



Day 46: Design Review 7

No Bag Day

It’s a very good day, it’s the first of hopefully many no bag days in future seasons.

For anyone new to FRC and wants to know a few of the reasons why so many in the community supported removing the bag for many years here are a couple good places to read more.

Everyone at FRC HQ and in the community that worked to make the removal of the bag a reality deserves a thank you. Giving teams the ability to choose how to use their resources (time, money, etc) is a great thing and will increase opportunities for inspiration through iteration and more time with their robots.

Design Review #7



Given your earlier experimentation with other vision systems (both Chameleon Vision and OpenSight) I’m curious to know what the LimeLight is doing there. Is it a backup in the event the other systems fail somehow, or being used for some particular reason?

1 Like

I don’t know if this has changed, and don’t take my word for it, but I believe earlier in the season they planned to use the limelight to view the power port vision targets while using OpenSight on another camera to detect balls and the loading bay vision targets

1 Like

Can you provide some more details on how you drive the V without the vp’s? We just smoked a whole bunch of N550s trying to do something similiar and I would love to see how you guys have your reduction set up.

It’s a VEXpro 12t 3mm pulley driving an 84t 3D printed pulley, so 7:1 reduction. We have current limiting setup on the SparkMAXs to avoid drawing too much current. Our belts are on 24t pulleys with 140t belts.

@merelephant is correct, it was always our plan to use a limelight for tracking the outter port.


Allen, what types of belts are those on your intake and where did you source them from?

What infill/material is your hood being made of?

Should be 5mm HTD belts sourced from vbeltguys.com

1 Like

Intake is 3mm HTD - 9mm width from NEO to first roller and 5mm HTD - 15mm wodth from roller to roller.

The funnel is 5mm HTD - 15mm wide with two stacked together. We have an unreasonable amount of 140t 5mm HTD 15mm wide belts from some ordering mistakes in 2017.

Belts purchased this year are from vbeltguys, we also have belts in stock from vexpro, polytech, and vendors on AliExpress/eBay.

1 Like

@AllenGregoryIV Do you know if Dacron Sailcloth works with iron on numbers?

We used iron on vinyl in 2018, it “worked” but we had a lot of peeling of corners and had to repair/restick corners a lot.

If you don’t mind me asking, what do you use with the sailcloth then?

Phil, the best material for numbers for sailcloth would be the material they use for actual sail numbers which is adhesive backed insignia cloth or adhesive backed dacron. You would need to have a way to cut the numbers yourself using a laser cutter or similar.

I have used adhesive backed vinyl numbers successfully as well (for sailboats) which is what Andymark sells. Based on how these performed on sailboats, I think they would do pretty well on bumpers as well.

My experience has been with actual sails, not robot bumpers (we are using them for bumpers for the first time this year) so @AllenGregoryIV might have better information regarding the best way to apply numbers for bumpers.

Edit: Also added adhesive backed dacron sail number material to the list.

Disclaimer: Never used sailcloth before. Our order of sailcloth came in yesterday.

I don’t feel like any kind of adhesive stickers would adhere well to the sailcloth based on its texture, at least not well enough to survive multiple competitions with high bumper-bumper contacts.

It’s true that sails don’t generally see a lot of contact with other objects like bumpers do. But if you have ever seen a sail luffing (flapping) in a strong wind, you would realize that those numbers need to be pretty well adhered.