Catapult VEX IQ consistency

Hi everyone,

I have finished building my catapult, but it is very inconsistent. (My catapult is based on Ben Lipper’s Design).

Any help?


Can you be more specific and describe what is happening?

Are the balls spreading apart? Is one going far and one going short? Are they shooting sideways? Are they going too far? Too short?

A video and a run-down of what’s happening will help us narrow down the problem and be able to give you the help that you want. Right now, in our minds it could be any of the things above.


Any videos and pictures that might help?


Sure thing, I can get them tomorrow. And the balls spread apart, and sometimes when I’m aligned perfectly it goes short, and then it goes past the basket. I have coded my catapult, yet these problems persist.

Here’s a video of the catapult shooter, and even though most of them go in, I want it to be more consistent so that when I run the timer the balls don’t spread that much even if I’m not on the best angle for shooting.

It’s not available, if you could upload I on Google drive

How do you do that? (20 characters)

Go to Google drive and tap the plus button. Upload the file and set the sharing to anyone with the link

It says “we’re still processing this video.”

Here’s the link:

As you can see, I did move a little the 3rd time, so i missed them, but the last one was aligned yet the balls missed, and even then, I want the spread to be a little less so I don’t have to align it perfectly every single time.


Do you have an even amount of rubber bands on both sides, if not that could be the reason why…

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Hi. Obviously there is a limit to how much I can help since I cant see your robot up close in person but I do think that as another user stated if the force on your catapult is not evenly distributed it might cause some inconsistencies. You should check just to make sure your rubber bands have equal force on both sides. Also, this could have something to do with how the balls are positioned when they load onto the catapult, but I cant say for sure especially since they seem to be in the same spot whenever they are loaded.

I do have an even amount

Would you like some up-close images?

Yeah that could be helpful

Sorry I can’t be more helpful, but

  1. Have you noticed that the ball closest to the camera always goes farther? Hmmm…
  2. Do you have a hard stop? (On both sides obviously.)
  3. Your balls don’t look very secure in their holes. Do they look to you like they’re kind of rolling around?

The first shot, the right of the robot is close to the black line on the right of the robot. Every other shot afterwards your robot seems to be farther and farther towards the left side ( farther from the line on the right side). I suggest you place your robot with your hands “perfectly” for line up before shooting instead of driving into shooting position. This is the only way you can truly test your catapult consistency while keeping everything else constant. I hope that helps.


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Answer to 1: I actually saw that numerous times, but it varies widely from one side to another.
Answer to 2: What do you mean by “hard stop?”
Answer to 3: Do you have a solution to this problem?

Thanks! I’m trying to make it closer together when it releases though.

Here are some pictures I took: