FRC 4481 Team Rembrandts 2023 Build Thread

Week 6 - The day formerly known as Bag Day approaching

Week 6 already, and we are thanking the robot gods that the bag day was eliminated years ago. With such an ambitious robot design, supply issues, and local holidays it’s been a crazy race to the finish here in week 6+. Now that the dust has settled and we’ve had our local reveal its time to catch up on the #openalliance posting. We are proud to present our almost complete robot “TR-X’’ along with the development/practice robot Chomper.

We keep adding videos to our playlist on YouTube. Go check them out: Build Season 2023 - Robot Development. You may see some previously unreleased videos of our spindexer testing and development. Please remember to like, comment, and subscribe to let us know you enjoy the content and would like to see us continue to post this volume of videos in the future.

Robot Status
A picture is worth a thousand words (or a thousand hours of work). Let’s let some photos of the robot do some of the talking.

Week Six Recap Video
The media and branding team continues to deliver awesome recap videos of our build season, please take a look at the recap from Week of Build Season:

Robot Reveal Night - Family and Partners Event
Last night we had an amazing time showing off our robot to all our parents and partners! We’ve come a long way since kick-off and can be more than proud of the result. You can see some footage of the robot being demonstrated by our drive team:

Lessons Learned
Schedule, schedule, schedule and have a back up plan. We ran into some supplier issues for some of our competition robot parts and had to scramble to align some additional resources, we will need to evaluate this for next season and perhaps add additional capabilities to our in house fabrication.

Next Steps
All members of the team are now divided into groups to focus on the top priorities for the next few days before the team travels to California. The controls department will continue with software development for autonomous and tele-operated control. The mechanical department is focused on preparing spare parts and making the final tweaks to the competition machine. The awards team and media and branding are focused on preparing our materials, presentation, and students to talk to judges. Everyone is starting to pack for the long flight, and leaving space in their suitcases for the robot components and subassemblies, that’s right, the robot is going as checked luggage again this year. Good luck to all the teams competing soon, we look forward to our trip overseas and competing in California again!

This post was written by: @Justin_Foss


Are you still running the lazy Susan open loop? If not, what sort of time improvements do you expect to see by automating it?

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We currently make use of 2 differently positioned photoelectric sensors to control the lazy susan/spindexer.

You can see them in below screenshot

I bet we have a state machine logic diagram somewhere but I’ll try to explain how it functions.

  • While intaking the black roller and side wheels spin at certain speed, once the game piece enters the spindexer it gets detected by sensor 1.

  • That detection means that the black rollers and side wheels start spinning a little slower to prevent the cone from getting kicked out of the spindexer while rotating.

  • Once the cone is in the spindexer it starts spinning in the direction that the cone hits the TPU 3d printed end stop. This end stop is strong enough to hold the cone into position while it’s sliding on the floor.

  • In the floor is a piece cut out to allow the cone “drop” with it’s square piece in there. Through doing that the cone pockets in the floor and thus giving the spinning floor more “grip” since it can actually push the cone now.

  • Once the cone enters the gap cut out it will be pushed through the TPU end stop and sensor 2 detects it’s fallen in the cut out.

  • It will then speed up really quickly to finish it’s rotation untill sensor 2 detects the cone again and then stop.

  • After that the gripper and telescopic arm come in straight away to grab and lift the cone out of the spindexer.

This all can be seen in this video:

In our latest uploaded video you see the arm move away from the spindexer while intaking to make sure the cone doesn’t hit the grippy compliant wheels of the gripper.

So the concept is evolving and turning out to work relatively well and quickly. It’s all in the software details and automation now. Hopefully we have enough time untill sunday to smooth all things out.

Hope that answers your question! If not let me know.


No problem! Below you can see a couple images of the telescopic arm setup.

It’s a completely custom design and produced in-house.
It has a fixed tube that’s mounted on the crossbar to the pivot. This tube also holds the gearbox at the end which runs a NEO motor through a belt gearbox. This gearbox drives another long belt which is mounted and fixated on the inner moving tube.

So it’s a belt that’s open loop, cut open, and then mounted inside the moving inner tube through 3D printed parts. The belt is looped in there and fitted in a tooth printed profile. By tightening the bolts it allows to “pull” on the loop and thus tensioning it.

So the belt never makes a full rotation, it just carries the inner tube from the beginning to the end as shown in the images below! Hope that answers your questions!


Nice work, fantastic implementation of a spindexer! Favorite bot so far.


Weekend Update - The Finishing Touches
The last weekend in the shop before the team heads off to California to play our first two events was a busy one. The team was putting the finishing touches on the competition robot, manufacturing and packing spare parts, preparing materials and practicing for talking to teams and judges, and filming for an official reveal video. Now the robot is being disassembled into is subsystems in order to be packed into suitcases and checked as luggage onto the plane. Thanks to an Apple AirTag we have been able to track our Pit Flightcase, so we know that it has safely arrived in California and is waiting for us.

We will be competing in California at the following events:
Week 1 - Hueneme Port Regional
Week 2 - Ventura County Regional

We are looking forward to competing and hanging out with our west coast friends this season.

Additional videos continue to be added to our playlist on YouTube. Go check them out: Build Season 2023 - Robot Development . Please remember to like, comment, and subscribe to let us know you enjoy the content and would like to see us continue to post this volume of videos in the future.

It is just me, or do robots just look better with bumpers on these days?

This post was written by: @Justin_Foss


what are the sizes of your inner and outer tube on the telescope? Something tells me that the inner tube has to be smaller than 1-1/2" (38mm)

Thats a good guess indeed. The inner tube is 35x35 (mm), and the outer tube is a 50x50 mm tube. Both tubes have a wall thickness of 2mm.


Team Rembrandts | TR-X | Ten Seasons of Youth Inspiring Youth
Team Rembrandts has proudly competed in the FIRST Robotics Competition, in that time we have grown, but the mission remains the same: Youth Inspiring Youth… Inspiring You. While the travel team is somewhere of the Atlantic Ocean on their way to California the team at home is still working. Our media and branding team have put together a video celebrating our 10th season focusing on where we came from, where we are, and where we are headed.

Please take some time to view what they have put together, and don’t forget to like, comment and subscribe to follow along with the team as they prepare to compete this weekend and next.

This post was written by: @Justin_Foss


Hey there! Sorry in advance if this question has already been answered… I searched around but couldn’t find it anywhere.

What materials are you guys 3d printing with for the pieces on the arm/crossbar. Specifically, the pieces which join the crossbar, sprocket, and superstructure together. The pieces in question are the orange parts circled in red below.


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Hi Gavin. Thank you for your question!

There are many 3D printed parts in our robot. Most of the parts are printed from PLA or Tough-PLA X3, both printed on our own Ultimaker S5’s. In addition, we can also print with IGUS iglidur i150 material on these Ultimaker S5’s. This is a great material to make printed plain bearings that is really easy to print with the Ultimaker S5 printers. The material is self lubricated and has high abrasion resistance at low surface speeds so it doesn’t wear a lot in time.

To answer your question where the selected parts are printed from I’ve made a screenshot to explain it better:

Superstructure = Red
Rotating tube = Green
Printed Tough-PLA = Blue
Printed IGUS iglidur i150 = Pink

There is a fixed shaft that is connecting the left and right sides of the superstructure. The blocks in the tubes are made of Tough-PLA that ensures a better stiffness of the whole superstructure and prevent the tubes will bend more easily.
In between the arm and the superstructure are just simple round 3D printed spacers made from Tough-PLA. The 3D printed gear and the brackets that is holding the large sprocket are also made from Tough-PLA. There are no extreme forces on those gears, it’s just to drive the encoder with an 1:1 ratio with the rotation of the arm.
The inserts in the horizonal tube are made from the IGUS iglidur i150 material. We also use the same iglidur i150 material for the sliding bearings inside the telescopic tube.

I hope this answers your questions.


Official Reveal Video - Presenting our 2023 Robot - TR-X
You may have been following along and know what our robot looks like already, but that doesn’t mean the Media and Branding department didn’t want to add a little spice and do a release video. We are proud to present out 10th robot, TR-X!

This post was written by: @Justin_Foss and @Sandwich21


Love the spindexer and curious about the diameter of it. Could you guys share the dimensions?



Great performance at Port Hueneme, our team was cheering for you while working on our own robot ^^;

Our team has a design structure similar to your team’s arm and gripper. We are facing an issue with the wiring for the gripper that runs up the arm, as the igus chain is mounted on top of the arm and it comes out of the frame perimeter if we move backward. I noticed that your robot has very clean and simple igus wiring, with the orange 3D-printed piece supporting the igus on the arm. I was wondering if you walk me through the process of how you guys came up with it, as our team would like to do something similar. Additionally, how did you secure the end of the igus chain onto the gripper?


Hey Preston,
I’ve asked our mechanical department. It has a diameter of ~380mm (~15 inches). Hope that helps you guys out, be sure to reach out if you need more information!

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Hey Yuvraj_Dhadwal
As for you question about the Igus chain.
The 3d print on the consists of two parts which form a tube around the chain.
One of the sides of this tube has small extrustions which fit in the chain profile so that when the cap is mounted the chain gets trapped.
As for on the gripper we just ran a bolt trough an open chain link and then kept in straight by using a ziptie (see foto).
To keep the chain stiff we basicly just tighten the ziptie to “tension” the chain to keep it straight.
As you can see in the picture is bows inward slightly. This keeps the chain straight.
For further questions feel free to reach out.

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Is there a reason you aren’t running the ground pick up for cones during matches? I was hoping to see it working during practice matches today but haven’t seen it yet. Is it just inconsistent? I see the cube ground pickup is working well :slight_smile:


It works okay enough, its just that HP station is just quicker. If you want to see it in action check our matches on Saturday at Hueneme Port last week.


This was exactly our reason for not running ground pickup in our week 1 event as well. With some more practice that may change


It may have been a bit quiet here in our build thread recently, but it has definitely not been a quiet two weeks for the team. We are all recovering from competing back to back weeks 1 and 2 (as per our usual schedule). The travel team is packing up and on their way home today, and the group who stayed home is recovering from staying up into the early morning two weekends in a row… that 9hr time difference is rough on the those of us gathered in the shop to watch the event, do all the remote scouting, match strategy preparation, match feedback, and remote technical support.

Before and between events the team took some much deserved rest and relaxation doing touristy things like hanging out at the beach, eating tacos, and enjoying the warm sunlight. Now onto the events.

Week 1 - Hueneme Port Regional
After landing in the USA the team settled into the hotel and then began the process of reassembling the robot. We were able to connect with 4414 who offered their shop as a place to do the reassembly and system checking on the robot so that we could be ready to roll as soon as the practice field at the competition was available (see image above). On top of that 4201 let us use their practice field to begin work on improvements to our autonomous and teleoperated driver controls.

We knew going in this was going to be a tough competition and it lived up to our expectations. Thanks to the preparations we were able to get through inspection very quickly and maximize our use of the practice field. Qualification matches went well and at the end we ranked 4th. With alliance selection the number 3 seed, 6036, selected us and then rounded out the alliance with 3859. We were able to win all our matches in the top half of the bracket, resulting in us facing off with the number 1 alliance (1678, 4414, and 696). The resulting set of matches were some of the closest and intense matches the team has ever seen. It was 4.5 matches of hard work, and in the end the number 1 seed took the win. If you haven’t seen these matches… go over to The Blue Alliance and watch them. Lots of interesting strategy and game play to learn from.

We learned a ton from this event and walked away not only as finalists but also collecting a Creativity Award for our robot design, with highlights on the spindexer. You can check out more about our robot in this Behind the Bumpers interview from FUN.

Also be sure to head over to our YouTube channel to check out our recap videos from each day at competition, for example here’s the video from Day 6 featuring the play-offs and awards ceremony:

Results: Ranked 4, Picked 3rd, Finalists [13-4-1] Creativity Award

Week 2 - Ventura County Regional
Back to the same venue with a new group of teams, some mechanical changes, and much improved autonomous options. Thanks again to 4414 and 4201 we were able to implement the following changes to our robot: new slicker material bumpers, mounted slightly higher, reduced the number of wheels on the intake to lighten it and add weight to the chassis. Improved laser cut clocking gears on the gripper and a few other small laser cut and 3d printed part improvements. We couldn’t get the robot to where it ended up without the support of these local Californian teams.

After reviewing our match schedule we felt that we had a good chance to seed higher at this event then week 1. We approached every match from a strategic perspective with a focus on securing the ranking points over total match score. At the end of qualifications we ended up in 2nd place behind 4414, both of us undefeated and within two RPs of each other.

For alliance selection, we were invited to join 4414 to play from the number 1 seed, and the alliance was rounded out by team 4. Through some hard fought matches and tough defense (shout out 1138) we were able to win out the event undefeated. It was an incredible run and we are super proud of our team, and our alliance’s performance on and off the field.

Speaking of off the field, 4481 really is a team about more than robots. One of our young team members Merle was honored with a FIRST Dean’s List Finalist Award, noting her contribution to the team and to the community. Congratulations Merle!

As members of both The Compass Alliance and The Open Alliance we seek to improve all teams FIRST experience from the ground up. In our community we work closely with our partners on our sustainability and impact on our students while supporting FTC Netherlands, now FTC Benelux (which supports the FTC League for Belgium, The Netherlands, and Luxembourg), to not only grow but be sustainable as well. We were honored to receive the FIRST impact award for these efforts.

We are proud to present our impact award video submission:

Results: Ranked 2, Picked 1st, Winners [14-0-0], Impact Award and Dean’s List

Lessons Learned
Slow is smooth and smooth is fast, this game is all about not wasting time and making every action count, this is even more apparent when collecting and scoring game pieces in specific locations on the scoring grid. Make every pick up and placement stick, then work on doing it a little faster each time.

The charging station and the cable guides really upset the CG of the robot. I think we knew this, but seeing fast driving swerve drives brings a whole new dimension to it. Care must be taken around these areas even for robots with a relatively low center of gravity.

Next Steps
Step 1 - Recover from Week 1 and Week 2
Step 2 - Welcome the team back to The Netherlands
Step 3 - Critical design review of the robot and the events as a whole
Step 4 - Do the work determined in Step 3
Step 5 - Fly Back to Texas for World Championships!

This post was written by: @Justin_Foss