Trap door vs. Pooper

I have seen different designs on the internet on “pooping” the ball out the back and I was wondering which is better and what’s the pros and cons of each(also what I mean by pooper is the one with rubber bands)?

  • Trap Door
  • Pooper

0 voters

pooper is better in every way


except for one. being worse. :crazy_face:

Imo the popper design is better than a trapdoor because it doesn’t need any motor-sharing devices (ratchets, differentials, etc.). It also eliminates the need for a back plate of lexan/metal.


Pooper is better because the name is cooler


But wouldn’t the Trap door be better for something like a Design award while still accomplishing the same thing?

Maybe innovate or amaze, but probably not design (design is based off of the engineering notebook and judges interview).


Wait, you don’t need ratchets for the poop? Wow I’m doing something wrong.

Not if your robot has both an indexer and flywheel. You chain the pooper rollers to both the indexer and the flywheel.

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Trapdoors do require ratchets and motor sharing, but I have a design for one that may be faster than a pooper. I am still not sure, but it should be as fast as a well built pooper. I do not want to give much away, but it takes inspiration from the mechanism to sort bills in a money counting machine. Those machines can process bills at about 20 per second, so I think it is a fairly good fit scaling it up for balls. My design does have some notable downsides which may or may not outweigh its benefits as I’m not done building/designing it.


can we just not have this conversation?

Well I mean, the pooper is really just a name, not a joke (yet). Also I intrigued by this conversation because of how important this is to the meta. Also, For me, I could not get a trap door to work well. If you have a straight indexer, it is hard to make the ball shoot out the back. In reality, the trap door would be raised and the ball would be in a limbo as there is not compression forced upon the ball.


Does the trapdoor need to be raised though? In my design, the trapdoor would be able to close while the ball still has contact on the indexer, so compression would be maintained until the ball exits the robot. My design does have other flaws though such as slower ball movement/higher torque required to move the ball through it.

I think in vexU a trapdoor might have some merit cuz of the unlimited motors you have, if you are able to make one as fast as a pooper, but we will have to wait and see

For your design it probably works, it’s just for my robot it cant have a trap door work in the design. It seems easier to me to just make a pooper. But if your robot could use a trap door,
go for it because it has less things stretching and less failure points. But in general I think t the pooper is still a sound design

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The pooper is definitely a sound design that I am most likely going to do, but I still am going to build a prototype of each first.

I, for one, am partial to my own design.

Hmm I wonder who was the 1 who voted for trap door?


do you really want to make your robot slower just so it can be different for the sake of judged awards? maybe. But just being different isn’t enough for it to be worth it for me, especially when I didn’t even come up with the thing that makes me different.


but can we just not call it a pooper?