Spectrum 3847 - Build Blog 2020

Have you given up on creating a short robot that fits under the tunnel?
Or is this just a prototype Power Cell shooter?

We never tried/planned to build a short robot that fits under the tunnel.


We are headed in a similar direction, so thanks for all of the updates. After living through 2016 low bar, we aren’t going low.

I like the path the ball is taking through your robot, have you done much testing on how to hold and transfer the ball through the robot?

Not nearly as much as we would like, we just got more balls Thursday, so know that we can feel how they interact we are working on more of the options


Ok thanks, we just our extras Friday, so on Saturday we set up our first real rig to test the metering. Still determining compression and we are setting up guides on the side out of HDPE, hopefully it’s slick enough.

Day 9 & 10

Everybot and Week 6 Robots

This past Sunday, Spectrum was able to attend an event hosted by the Robonauts were Everybot and Week 6 demonstrated game play together. Both robots were very well done for only needing one week to complete.

Takeaways (Some are just confirmations of what we already knew)

  • The outer goal is very large. Week 6 was able to easily manually aim their robot to score consistent shots.
  • Fast low bots may have value in getting up to the RP level of balls but you need to be very quick in getting balls dumped into the goal and quick at intaking balls. Everybot does both very well.
  • The balance even on the wooden switch didn’t seem hard to accomplish. A reliable and consistent climb will be incredibly important.
  • Driving across the Dance Floor (rendezvous points) will test how robustly made a lot of robots are. Make sure you test your robot driving over 1" bumps (the kit 2x1 is a good approximation) before coming to your first event. We are going to see a lot of radios, roboRIOs, batteries and other electronics and connectors come loose if they are only zip tied loosely to robots.

More photos and videos are in our photo gallery.

Shooter Prototype V2

Hopefully will have test shots tomorrow after we make it a little more rigid.


Intake and indexing plans are still up in the air. We are re-investigating an intake similar to 971’s from 2012. At first we didn’t think it would package nicely but after some other changes to the design we think we can make it fit, but we need to build a better model to make sure it will index the balls fast enough for our robot.


Robots that inspired us today

2012 - 971 (intake & ball funneling), 2056 (ball funneling)
2013 - 180 (shooting game objects inside of your robot)
2017 - 125 ( 4-bar intake)



Day 11: Design Review 2

Tuesday = design review day

Here are some of the slides from today’s review put together by each of the subsystem lead groups.

Photo of V2 Prototype using HYPEblocks, hopefully we will have some testing tomorrow. We have to refactor the hood a bit.



tnx for the awsome blog.

why did you drop the drawer slides idea?

1 Like

Once we decided we would shoot opposite the direction of our intake, we no longer needed to shoot over our climber. This allowed our climber to be at the full 45" height at the start of the match, so we needed far less extension and thus the drawer slides were no longer needed. A single stage, chain powered lift, is far simpler for us to build and maintain.


Very cool idea for the climb system! Have you tested this prototype/idea? There are many steps in order to climb with another robot

  • Catch the iron bar
  • Lift yourself around 70 cm ~26 inch
  • Wait for another robot to drive into the forks which might be hard since the visibility is meh from the driver station
  • Lift yourself some more

This could be around 20 - 30 seconds. Did you try to time it?

Im glad that youre using Chameleon Vision (because Im one of the developers). Can you publish your experience with Chameleon Vision in this CD thread so other teams will consider using it. As its new for this year, not a lot of teams have used it or even heard of it.

Anyway, Thanks for sharing your team progress and for taking your time to create this detailed CD thread and answering everybody’s questions! :smiley:


No we have not tested it, it should be on a similar time scale to 2018 buddy climbs, likely 20-30 secs.

We can once we have more testing.

What is the range of motion of your elevator? What is the height when its collapsed versus when its fully extended?

Seeing is as it’s not designed yet it’s hard to say, but our design goals are for our latches to start somewhere from 28"-30" off the ground and be able to latch on to the pole at 63"+ some wiggle room.

Day 12: New intake/indexer Plan

Block Robot Update

The new intake plan, allows for balls to rapidly be brought into the robot with a wide intake, and set quickly into the tower using a powered V similar to prototype videos from FRC#6135, FRC#4481 and FRC#95 . We plan to prototype some variations of this idea by adding a central channel for balls to rolls straight down and possibly a powered belt to move balls towards the tower belting as well. We will test various options for the side conveyors/wheels and also speeds and direction changes.

The tray on top of the intake is designed so this robot would be able to load from the human player station with the intake down. That should allow us to intake balls on the ground and then quickly get any remaining needed balls from the loading bay when drive in.

When retracted the intake acts as a cage around any balls remaining in the funnel to not allow them to bounce out of the robot as we drive over the boundaries.

We have prototypes of these systems under constructed and will post video and photos when they are operational.



Terrific update. Thanks for the insight.

How is that shooter wheel constructed? Looks like 6" pvc on some type of hub.

Currently we are stacking multiple 6" drive train wheels as a shooter. It works, but is not the best approach for weight and inertia.


Currently testing with a very wide VEXpro 6" traction whee (lots of tires stacked together on a printed slicel. We will also test with 6" colson wheels.

Every time I look at your prototypoe shooter I admire how flexible it is to test! Ours definitely takes much more time to rework different configurations.

Flexibility is actually causing some of our issues, our hood isn’t rigid enough for proper testing, we are continuing to improve it.

Ah thank you for the info. I was feeling bad it takes us an hour to reassemble any changes.

Not to hijack Allen’s thread, but if you are looking for some suggestions we had good luck with rapid modification using a shooter prototype modeled after one in the 254’s 2016 Notebook.

Everything is fixed except the actual back cowl parts, one of which is highlighted in blue above. You can change the compression, backing, and release angle by just changing these out for different ones with a couple of bolts. This was designed around laser cut 1/2" plywood (because that’s what we have), YMMV.

It’s still in evolution, but something like 2 geared up NEOs running closed loop control was pretty happy. Not shown in CAD was we pretty quickly realized looking at the logs that we needed more inertia so the actual set-up has a pile of gears also on the shaft: