High School Legal CAD Design

Hi Everyone,

Unfortunately due to the current pandemic, PSU VEXU was unable to compete during this year’s competition for Change Up. As the semester winded down for college, I took some time this past week after finals to create a CAD model of a High School legal Change Up bot that was a combination of some of the best robots I have seen so far over the beginning of this season to act as a guide for any beginner teams or anyone looking for some interesting ideas. I have attached the google drive link to the CAD files below along with some rendered images by @vexreally Feel free to leave any questions!

900/600 RPM Front Rollers - 2 Motors (Blue)
1000 RPM Main Rollers - 2 Motors (Blue)
257 RPM Drive - 4 Motors (Blue)

Google Drive Link- https://drive.google.com/drive/folders/18nkUKBrYVIz8_jWQ2wdJcrFJf8nF8HG3?usp=sharing

COG Side Snip
Intakes Contracted

Some more renders are on the way!


wow this is really impressive! the renders are awesome and the overall robot design is really good and clean. props!

very epic


very epic indeed. :sunglasses:


Do the intakes flip out? And how does the hood pop up? Otherwise, the robot doesn’t look like it fits in the 18".
Nice job, though. Great robot.

The angled part of the intakes appears to flip out and the hood definitely flips out probably similar to 2011D’s hood. As far as I can tell the rest of the robot is in size and I assume this is true because of the thread name as well. The two part intakes are really cool I love the improved fielding angle while maintaining a linear path and compression for goal removal, really cool design.


I talked with Soham while he built this and you’re right. The main rollers are hard mounted and the outer chain and tread portion deploys. The hood is basically 2011D’s


I really like those intakes, and overall looks like it would be a very competitive bot if built. nice work!


Why no pooper though?? sick intakes btw

I like those intakes. Might have to take a closer look at this when I get the chance.

I decided to use both motors to create a 1000 RPM main roller ball cycle instead of using separate motors for indexing and shooting. This is because the idea of the bot is to have a very fast cycle time along with using some form of software indexing with line sensors and other gimmicks. One way I would recommend to properly index balls is to use the method that the skyline bots did with their indexer during the turning point season. (Link Below)

Another reason why I didn’t include the indexer is that in the recent matches I’ve watched, the game strategy has been to only top goals with the alliance color rather than sorting the balls completely out of the ball. Not having a pooper will increase overall ball path speed and not deploy opposing balls out on the field as you are cycling a goal.

Skyline Explanation-


Sorry for the late response but yes both the intakes and the hood flip-out!

As @Max_Johnson03 mentioned, the hood flips out in a similar manner to 2011D where the standoffs are attached on a screw joint at the top of the robot and the hood folds forward.

The only part of the intake that flips out is the final sprocket that is left with the flaps. The reason why I didn’t completely finish the intakes is that there are multiple designs from this point onwards. For example, the intakes can spin backward, and ratchet outwards slightly like a chain bar and allow for a wider intake angle (Similar to 4478D). Another modification that can be done is that the 4-bar on the intakes is modified to create an over-center lock that will lock the intake angle into a set position once they are deployed at the start of the match and allow you to also spin the intakes backward instead of expanding them outwards.

Another modification that I would recommend on this robot is adding something similar to 9181W that allow you to push up the goals slightly and intake balls faster. (Picture Below)



Sorry for the late reply, but why is this? Why does not having a pooper increase the ball path speed?

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Since both motors are powering all the rollers, the rollers accelerate quicker. Also, depending on how well tuned the compression and friction is, more torque on the rollers could allow them to reach a higher top speed

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Question about some of the polycarbonate. I’ve noticed that on many robots (and obviously this one) there are two very long ‘hexagonal’ sheets of polycarbonate or lexan hanging off the side of the robot at the drive base area. What do these do?

Do you mean the side wedges?

These are angled down long flaps that basically make it more difficult for opposing robots to ram you across the field from the sides. It is generally effective when used on a drive that is difficult to be pushed from the sides due to friction (such as a non-omni or bling drive). I’ve seen UK matches where the opposition almost tips themselves over as they drive up the angle of the wedges.

Does this CAD model use bling drive? If not I don’t really think side wedges would be that effective, other than making your robot look sickkkk.