Spectrum 3847 | Build Blog 2023

They are in our OnShape Swerve document here - Onshape

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I gotta say that I’m shocked out the outcome of launching the cubes. Do you think the wooden version of the grid has any impact on how those cubes land?

We were thinking early on about launching but since the cubes have seams they seemed to bounce unpredictably upon landing so we steered away from it. Those videos seem like they hardly bounce at all.

Amazing to see

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I don’t believe that the wood is what’s causing the cubes to not bounce much.

We are making sure the cube is launched with front spin which helps to keep it from wanting spin backwards off the grid.

We have found that cubes seem to bounce less after being compressed by the launcher wheels than they do if you just hand toss them possibly because the cube material stretches and then returns to it’s intial shape. During some tests it will look like the cubes have deflated, and then we can watch them “reinflate” as the material returns back to it’s original size.


Have you had any take any weird bounces after launch? Or is it as consistent as it looks?

Again great to see. I kinda wish we stuck to that path a bit longer!


Most of our tests can be viewed in the photo gallery - Week 4 - Spectrum 3847

Currently I think most of the inconsistencies are going to come from the launching rather than the landing but I’m sure we will get some bad bounces that fall out.


Day 25: Design Recap


We also made a Tiktok; y’all should go watch it.

MAXPlanetary ULTIMATE 2stage% speedrun (no-Loctite)


This isn’t at all accurate, you missed a critical step of the assembly process. You forgot to spend 20 minutes looking for the tiny key. For that reason, your run has been rejected.


How long until it’s submitted and verified on speedrun.com? Can’t get full clout if it’s not official :joy:


It’s not noteworthy until SummoningSalt makes a video about it.


Does a cone or cube fit fully in the intake when its retracted and with the elevator down? I saw a video on your website of some breif driving with cone stored in the intake, but the 4 bar was extended and raised and looked to have too high a C.O.G. for fast paced driving.

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Yes both fit, we are still iterating the rear portion of the intake that will properly hold and hopefully help center the cubes.

The tests on our Alpha robot don’t always represent our goals for actual match play. Our software is still a work in progress so we can’t always control our systems as much as we like and we sometimes want to see how the robot behaves in worse case scenarios.

In regard to CG, Alpha weighs approximately 80+ lbs. The competition robot will have a steel belly pan that will add ~20lbs and more ballast to get our robot’s total weight closer to the weight limit and keep our CG lower even with the elevator partially raised.

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Day 26: Practice Robot Progress

Our practice robot is coming together quickly. We had cut and powder coated all the rails. We are powder coating practice parts for two reasons, one we started competing with our practice robot more at off-seasons so it’s nice for it to look good, and it lets us choose the best-coated parts for our competition robot.



Our competition robot should be assembled pretty quickly behind this one, we already have all the rails cut and powder coated and the swerve modules assembled.

Progress will begin on getting the Four Bar components mounted on to practice robot, and then we will need to manufacture our V1 competition intake and launcher.

Launcher Progress

Changed all intake/launcher motors to Falcons, still running open loop and manual aiming.

More test videos where it misses are in the gallery


Is there shared CAD of your current launcher? When I look in the OnShape link at the top of the thread I just see some pretty basic sideplates. I am curious how the cube is tucked in to allow the rollers to spin up then how is it fed into the rollers. I am having a hard time seeing what is going on just watching the video. I do really like launching stuff.


The current version only really exists in real life, we haven’t CADed any of the rollers and have drilled a lot of holes into the wooden plate by hand. I did just update the version of Alpha in our main onshape document that has the Alpha V2 four bar/intake plates.

The current version doesn’t really hold the cubes well at all, it’s mostly just sitting on the 2nd lower roller that we added (it’s one of the things not in CAD anywhere).

The basket/funnel polycarb that will hold the cube is one of the big things we are still developing, we mounted something late tonight and it put a leak in the cube so we still have a lot to do on that.


Faces of inspiration. Well done!



Day 27: Cube Basket

The cube basket actually exists on Alpha now. We were pretty confident it would just be some bent polycarb and hadn’t really tried to solve the problem until yesterday. Today we added a lower basket that goes in front of the bumper during intaking and seems to work well. This setup allows the lower rollers to push the cube far enough back so it doesn’t engage the mid and top rollers and also helps center the cube if we intake along the sides of the intake.

We finally got to change the lower roller to the AndyMark Hex Spacer tube wrapped in ½” ID silicone and it works great for cones and cubes.

Our intake development is likely heading into the final stretch before designing the V1 competition intake. We still want to test REV 2in Compliant wheels on the mid-roller but we are waiting on a shipment for that to happen.

Here are some detailed photos of the current state of Alpha’s intake. We like to use mostly what we have on hand when prototyping so we can move faster. The top roller is a ball launcher roller from our 2017 robot with 3” WCP flex wheels stretched on top. The lower back roller is a spare intake roller from our 2019 robot, the mid roller was one of our very used intake rollers from our 2022 robot. Many of the pulleys used on this were printed in 2017 and just kept around for prototypes like these.

The printed bearing mounts make it much easier to change shafts/rollers since you can remove the whole thing and don’t have to push the shaft out of the bearings.

Sorry for the purple-tinted photos, the LEDs were on for some of the photos.

We are planning to have addressable LED strips up the sides of the robot for signaling our human player, and other robot status indicators.


Where could I find that white silicone tubing?

McMaster links in this post

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Thank you so much, that helps a lot!