7407 (The Wired Boars) Open Alliance Build Thread 2023

Welcome to the Wired Boars build thread for the 2023 FRC season! Team 7407 is a group of sophomores, juniors, and seniors who all share the same passion: robotics. This is our fifth season in FRC and our second year as part of the Open Alliance! Our team is wholly affiliated with Choate Rosemary Hall in Wallingford, CT, which provides us with an amazing robotics lab and machine shop complete with all the resources we need to work efficiently. We are fortunate to have FRC built into our school curriculum. Our team believes in fair and honest gameplay and prioritizes Gracious Professionalism and respect over anything else. We also created BoarBot, a simple, effective design that we will make available to other teams early in the season to give rookie teams a good budget robot to introduce them to FRC. Our diverse team is comprised of many amazing people and we have a fun dynamic. Through the Open Alliance, we are looking forward to sharing our team materials and progress with the community in order to make FRC more accessible for all. Last year was our best year in FRC so far; we made it to the semifinals in the Roebling Division at the FRC Championships in addition to winning the NE District Granite State event and winning the District Engineering Inspiration Award at the NE District Hartford event. We hope to continue our momentum this season to do even better at competitions and continue spreading our team’s values.

Team Website
The Blue Alliance
Github Code Repository
Onshape CAD - full robot
Onshape CAD - drivetrain

2023 Confirmed Competitions:

  • NE District SE Mass
  • NE District Hartford

Build Season Schedule:

  • Mondays: 3:45 PM - 5:45 PM
  • Tuesdays: 3:45 PM - 5:45 PM
  • Wednesdays: 1:30 PM - 4:30 PM
  • Thursdays: 3:45 PM - 5:45 PM
  • Fridays: 3:45 PM - 5:45 PM
  • Sundays (optional): 12:00 PM - 5:00 PM
  • As a class three days a week for 70 minutes
  • Other times as needed

We will be releasing a Kickoff update tomorrow describing our activities and process for Kickoff weekend!


We divided our Kickoff into three days of work. Day 1 was dedicated to acquiring an understanding of the game and the rules manual. Day 2 was dedicated to strategic and functional requirements. Day 3 was dedicated to functional and robot requirements. Like we did last year, we made a spreadsheet to summarize these requirements. We expanded on last year’s spreadsheet structure to include more details in the form of added strategies and points potential. This year’s spreadsheet can be accessed here and contains some exquisite knowledge.

On Day 2, we began work with the spreadsheet. Going by each stage of the game (autonomous, teleoperated, and end game), we thought of strategies that we could use in a match and then discussed each one and their functional requirements. Below are the strategies we came up with. Visit the spreadsheet for additional details.

Auto strategies

  • Move all autonomous pieces into the community
  • Score as many game pieces as possible (estimated 2-3 max)
  • Dock and engage + mobility
  • Score pre-loaded game piece, pick up second game piece, dock and engage
  • Launch pre-loaded cone and score high, pick up second cone, score second cone
  • Drop pre-loaded game piece, pick up second game piece, drop second game piece in community, pick up third game piece, reacquire game pieces one and two, score all three game pieces, dock
  • Score pre-loaded game piece (while moving?), pick up second game piece, dock and score third game piece, pick up fourth game piece, pick up fifth game piece, dock and engage, score fifth game piece

Teleop strategies

  • Floor Boi: pick up either game object off the ground from the ramp near the human player station (no tray), score game pieces at all levels
  • Homebody Energy: stay in the community, have partner(s) herd game pieces to you, score game pieces at all levels (spend 60% of time scoring our own game pieces, spend 40% of time scoring partners’ game pieces)
  • Human Double Station: keep going back to the human player station to pick up cones and then score them

Endgame strategies

  • Keep scoring game pieces
  • Dock and engage (no buddy assist)
  • Be the last robot to balance on an already balanced charge station
  • Dock and engage and take up minimal space to allow two partners to also fit
  • Couple with a second robot for a tandem balance
  • Triple dock and not engaged
  • Pick alliance partner up while docked and engaged
  • Dock and engage and overhang up to 40% of robot weight off the edge

Things to Keep in Mind

  • Alliances will heavily defend their community.
  • Don’t seal yourself off from strategies or functional requirements by overly relying on other teams to accomplish what you want your alliance to accomplish.
  • Stay unpredictable during matches.
  • Getting two robots balanced on the charge station is very important.
  • We need to explore the feasibility of getting three robots balanced on the charge station.
  • Do we want to focus on cones or cubes?

I will continue updating this post as we keep talking as a team. The spreadsheet is live.


Holey Moley It’s Week 1

Jackson’s posts above provided a team intro and kickoff weekend recap. The students have been busy in class the today (Tuesday) and yesterday working to:

  • Refine robot functional requirements
  • Begin basic hand sketches and 2D sketches in OnShape to ideate potential robot layout
  • Determine finalized (we hope) robot drivetrain dimensions in OnShape
  • Cut and then paint our drive rails (REV MAXTube - grid pattern)
  • Begin 3D printing some components on the MarkForged - highlights below

We’ll have more detailed updates from sub-teams throughout the week but wanted to highlight a few things specific to our planned primary construction methods this season. The team has limited manufacturing capability in-house beyond the popular Omio CNC, so we’ve learned to work frequently with COTS aluminum extrusion like Vex VersaFrame and more recently the new REV MAXTube line of products in combination with custom-designed 3D printed gussets, plugs, connectors, and other random bits and pieces made on our MarkForged machines using Onyx. Our 2022 off-season thread showcases these parts extensively on our turret rebuild.

REV MAXTube and Tube Plugs
Write-up by one of our students Asher C.

This is a 3D printed (Onyx) insert that is designed for use with the REV 2x1 aluminum tubing with Grid Pattern. This specific tubing has internally braced corners and a standardized hole pattern on all 4 faces which we expect will be useful in construction and assembly of our robot. The purpose of this insert is to reinforce the tube internally and prevent, in combination with the bracing, the tube from collapsing when through-bolts are used to connect individual pieces together using gussets to form a traditional frame. We’ve designed these tube plugs to accept 10-32 bolts all the way through the tube or threaded insert for shorter bolts going through only one face of the tube.

Straight Insert for Through-Bolt

90 Degree Angle Insert w/ Threads

We will be sharing a CAD file for these inserts in the next ~24 hours so that other teams can make there own as desired! Some additional details are below:

  • Adjustable length as needed (example shown 3 inches)
  • Through holes on all side are .25" and .5" apart from the center point
  • Each edge is chamfered by 0.125" radius
  • Use fillet on all four the corner edges on both 1" faces of the insert
  • Use fillet on both 2" face edges on each base

Hi everyone! I’m here today to elaborate on elements of James’s post from yesterday about what we’ve been doing this week. This week, we’ve been conceptualizing complete robots that can address as many of our most valuable requirements as possible (more on these requirements below). Our overall approach with the creation of the robot is to proceed simultaneously with different subsystems (i.e., drivetrain, intake, shooter) in order to accomplish some parallel manufacturing and design. Regarding the drivetrain, we’re still deciding on what size we want it to be as there are benefits to having both small and large drivetrain sizes. On one hand, we want to have a small robot for the bridge. On the other hand, we want to be stable on the field for defense. Regarding the intake, we’re currently developing both cone and cube intakes.

Here is a list of our top priorities as determined by our team discussions:

  • Drive
  • Intake cube from floor
  • Intake cone from double station
  • Accurate movement in autonomous
  • Drive over charge station to retrieve game pieces in teleop
  • Prevent beaching
  • Dock in auto
  • Dock in teleop
  • Shoot high cone
  • Shoot high cube

Intake CAD
Prototype Sketches

(For reference, Wednesdays are our weekly update day so look out for more posts like this in the future).


Here is a link to our current CAD for those who want to follow along!


This pneumatic intake/extake prototype was designed with inspiration from Ri3d Redux’s testing. The intake is pretty simple in concept, it compresses the cone/cube from both sides to hold it using a pneumatic. This prototype allows the game piece to swivel under gravity as the pads holding the piece are attached to bearings. The intake worked very well for cubes, but with cones, it had a couple of issues. The first issue was if we grabbed the cone too low. If we grabbed it to low, gravity would swivel the top of the cone down, making it entirely impossible to score. A second issue we noticed was that if the cone was grabbed too far off-center the cone would not be perfectly vertical. A solution to this second issue could be making the grabbing pads larger. Our main takeaway from this prototype is that this idea would work, but it would require a high level of precision in many ways. For that reason, we are putting this grabber concept on the back burner while we look at possible ways to make a grabber with rollers.


Quick follow-on update to Jackson’s earlier post with some more media.

  • Videos of the pneumatic gripper proof-of-concept
  • Photos of drivetrain manufacturing progress
  • Early CAD update

Video Link
Pneumatic Gripper - Cone and Cube Test
See previous post for description of functionality and photos. This is an early proof-of-concept that did not work out exactly as hoped. We’ll be moving onto some other ideas quickly.

Drivetrain Update

We have now cut and painted our drivetrain’s inner and outer MAXTube rails. We’ll begin assembling our swerve drive and add a temporary bellypan with some electronics to allow programmers to start some of their work. Depending on finalized superstructure design and attachment method, we may need to come back and make additional small modifications (drilling holes, etc.) to the MAXTubes, but that is TBD.

Last season we were fortunate to have powder coating access thanks to a few other local teams who had ovens that we could use, but the process was time-consuming taking all of our materials off-site every time we needed to paint + assemble our mechanisms. This year we are trying spray paint instead in order to cut down on time and keep everything “in house”. The 2022 robot was primarily navy with gold accents. This year we’re doing quite a bit more gold.

CAD Progress

Our CAD model link is available in the original post above, but this is a screenshot of where we sit today in the main model. We have a few game piece manipulator ideas sitting in their own files as well, which we will use to help with our prototyping efforts.

Currently represented in the model:

  • Drivetrain - REV MAXTube frame with SDS MK4i (NEO’s)
  • “A-Frame” - REV MAXTube with angular gussets
  • Arm - Planned to modify a Thrifty Elevator to simulate the Team 401 “Not-Quite Pink Arm” from 2019 which we are tentatively calling the Great Value / Kirkland Signature / Good & Gather / Generic Brand Pink Arm
  • Wrist - Mostly TBD in terms of design, but absolutely planning to have a wrist at the end of the arm
  • Forks? - Very early CAD ideation for some endgame magic which likely deserves its own post soon!

Small photo update of the drivetrain! We had some very productive classes this morning!


WEEK 1 HAS CONCLUDED! I wanted to pass along our recap video here:

Week 1 Video Recap

(Hippie Rock by Serge Quadrado is licensed under a Attribution-NonCommercial 4.0 International License.)


Here is an update on our double station/ claw intake. Since our first clamp claw, we have gone through two iterations. The first was an attempt to use Mecanum wheels to bring the cone up so we could consistently hold its base. It is in the linked Onshape file below (Mecanum Roller Intake). Some videos are also attached. This did not work as well as we anticipated as the mecanum wheels did not grip the cone nearly as well as they needed to, even with compression. We also found that the 3-inch compliant wheels were not as grippy as we would have liked.

With these issues in mind, we replaced all the wheels with thrifty squish wheels (4-inch wheels in front, 2 sets of 2-inch wheels in back) This worked extremely well on both the cone and cube. It even worked on tipped cones if the top of the cone was at all facing the intake and often turned them right side up. This intake is a very good option, however, for our purposes, we would like to find a lighter alternative.

With lightweight in mind, we looked to reduce the number of wheels while maintaining constant contact and control with any given game piece. We looked at alternative materials/parts that had a good grip on the cone. We found that our latex surgical tubing had an amazing grip on the cone. At first, we tried to mount the tubing but realized that would be impossible so we looked at latex alternatives and found out about liquid latex. Bad news; it is extremely hard to get, especially in smaller quantities. Because of that difficulty, for this prototype we used Plastidip. With this intake, we also experimented with pneumatic actuation and made a gear cutout on the arms so they are linked and only require one piston. The CAD for this version is also in the Onshape below in the folder labeled “Belt + Thrifty Wheels.”

Earlier today we tested this intake and found some great success with it. It intakes upright cones with no problem and grips extremely well. It can also pick up tipped cones and rotates them so the bottom is facing up (good for our elevator/arm robot idea.) The only orientation it seems to struggle with is when it is facing the cone’s bottom head-on. In that orientation, it still grabs the cone decently, but can not put it right side up. Cubes were no problem at all with this intake. The range with which this prototype can intake is also pretty good. We were able to get cones and cubes that were just barely touching either wheel with the arms fully spread.

One thing we noticed with this prototype was how quickly the Plastidip fell off the belts. Tomorrow we are going to test without any Plastidip to see if it is even necessary but regardless we are hoping that the liquid latex we will eventually get will stick to the belts better. We also noticed that when taking the tipped cone head on it would sometimes not self-right and drive itself toward the swivel point. We think approaching it at an angle could help reduce the chance of this happening, but a more mechanical solution could be some ramps to push the cone tip either up or down.

Feel free to respond to this thread or message me with any questions

CAD: https://cad.onshape.com/documents/1f379f0008d00f1438bb322f/w/2bc4eac3d8f648b3365adfed/e/e84751d7f596d68ed54a3bff

Drive Folder W/ videos: https://drive.google.com/drive/folders/14OkAIPbKUDqfgNYZtN0YJ5cWK6dFnBAb?usp=share_link


Could you please share the cad files for these onyx inserts? They look very handy! Thanks!

How’s the paint holding up? Any tips or prep work you guys have been trying?

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My apologies I did not update the post. Here’s the link from our student designer: Onshape Link

Please let us know if this does not work!

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The team is quite happy with how the parts turned out given how fast we were able to turn them around. We did do the painting outside on a sheet of cardboard and did not control for dust, humidity, temperature, etc.

Of course, this post by James from Team 95 is definitely the go-to guide on spray painting the “right way” for best results.

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Spray painted parts hold up okay over a season. They well patina/wear a bit, which I think adds good character to the robot. It’ll still look great on a webcast and from the stands. You can always brush-touch bad scrapes (spray paint into a cup, then apply paint with a brush) if they’re really bad and/or making you sad.


Week 2 Updates:

Unfortunately, we were unable to get this post out yesterday. Fortunately, however, it’s up for you all now! We’ve been up to a lot this week and been very productive.

For updates on our claw intake, @Garrettc did a lovely, detailed post a few days ago, so check that out for updates on that. Below is a photo of our progress with that so far. The links to the CAD and more photos/videos are also in his post.

Our A-frame subsystem has been fully CADed and manufacturing and assembly are underway! We’ve manufactured all the in-house parts we’re using, but we are still waiting on some COTS parts to arrive. Because the tubes we’re using this year don’t work with the bearing block assembly from the ThrifyBot elevator kit, we’re working on modifying it. The issue is that the holes don’t line up. The solution we’ve come up with is to create 3D-printed inserts. As you can see from the below image, we’ve also started work on our electrical layout. As we haven’t figured out the dimensions for our elevator just yet, we haven’t had too much progress in this realm. We have opted for polycarbonate swerve drive module covers so we can see what’s going on with the modules. This can be seen (sorta) in the right corner of the drivetrain.

Regarding manufacturing, this week we’ve been lathing shafts, CNCing some polycarb and metal parts for the A-frame and the claw, and cutting tubes for the robot. Here is a picture of our CNC machine at work. Many of the parts we fabricated this week can be seen in the above photo.

Here is a screenshot of the most current full-robot CAD. Again, the Onshape link can be found in an above post if you want to check it out yourself. Not pictured in this CAD (because it hasn’t been CADed yet) is our ground intake for cubes and accompanying handoff system. It’s going to an over-the-bumper intake that will intake cubes from the ground and hand them off to the claw that’s on the end of the pictured arm.

Finally, be on the lookout for comprehensive scouting and Impact Award updates.

Feel free to ask any questions or leave any comments and either I or another member of our team will get back to you as soon as possible!


What feeds and speeds are you guys running on your router?

Our team has a similar design and I am curious if you guys have any cool ideas for running the wires up the arm/elevator.


Right now for the linear extension on the arm we are planning to use this energy chain to hold the wiring that will go to the wrist/claw. We will run it along the side of the arm in similar fashion to a boom lift (pic below) and will hold it in tension using a constant force spring roller setup. We will plan to post more photos as we build this.


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We have a few different settings, depending on the material. We mainly use an 1/8" single flute flat endmill for all our cuts. We have been using the “aluminum finishing” or “plastics finishing” settings built into Fusion and have found those settings work well. For bores we change the following:

  • uncheck “use ramp angle”, set pitch to 0.381mm
  • set direction to “conventional”
  • add -1mm on bottom height to ensure cut goes all the way through

For pockets we change the following:

  • add -1mm on bottom height to ensure cut goes all the way through
  • uncheck “stock to leave”
  • check “multiple depths,” use 0.4mm for max. roughing stepdown for aluminum, 1mm max. roughing stepdown for polycarbonate
  • set max stepover to 0.4mm for aluminum, 1mm for polycarbonate

For 2D contours we change the following:

  • add -1mm on bottom height to ensure cut goes all the way through
  • check “multiple depths,” use 0.4mm for max. roughing stepdown for aluminum, 1mm max. roughing stepdown for polycarbonate

We also use the 6mm single flute flat endmill for large pockets and contours on 1/4" aluminum plates. Here is what we change for feeds/speeds for the 6mm:

  • Spindle speed: 16,000rpm
  • Cutting Feedrate: 550 mm/min
  • Plunge Feedrate: 127 mm/min

For pockets and 2D contours with the 6mm flat endmill, we use the following stepdowns:

  • 2.5mm max. roughing stepdown
  • 2.5 mm max. stepover

Hope this helps!