Catapult problems

My team is using a double catapult and one of them is not shooting as far as the other one and we already used a shaft to aline it

can you send pictures?
there can be many causes, and pictures will help find those


This is a perfect situation to use the engineering process.

  1. Is it always the same side that is shooting not as far? Test a number of times to prove this.
  2. The side that is shooting “shorter”, does the balls always land in the same position? If not, why is that?
  3. The side that is shooting longer, does the balls always land in the same position? If not, why is that?
  4. Are using using the same balls every time to test? What happens when you switch the balls around?

Once you have answered a lot of these questions, you will soon find out the possible solution to your question.

I hope that helps.



The most important thing is: Is it consistent? Even if it’s consistently wrong, at least it’s not going weird all over the place and you have no idea what changes between shots. Try this:

  1. Set your catapult up perfectly. Line it up where you want it to shoot from and where you would expect it to make it every time.
  2. Get all the balls available to you and set them in a pile next to you.
  3. Have one person load the balls and another person watch them, from different angles and very closely.
  4. Shoot over and over.
  5. Try to figure out exactly what the problem is, and then figure out a solution.

If you want anyone else to help figure out the problem, you will need to video this from several angles and send it to them. Send multiple shots; one could be a fluke.


Did it shoot even before and now it doesn’t?

Is it built symmetrically?
Are the bands put on evenly?
Is any component broken? (Look closely)

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@bash371 got stuck with the standard “engineering response” on their question.

Which as a question is pretty good. States a symptom and a possible fix “Shaft to align it” (spelling fixed) that didn’t work.

They were met with a barrage (4 posts) of requests which they have not gotten back with an answer. Which is standard around here, we want a picture, the code, a better description (does on fire mean smoke, flames or 2’ tall flames) etc.

Not sure if it’s lack of access to the robot, they fixed it, etc. They have been on since the request for more data was asked, so a positive point is they are still alive.


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All of these threads discuss possible solutions to your breakage problem. Give them a good review.


It may be the photo perspective or my eyesight but the catapults don’t look even. I dropped three parallel lines in the photo below. Could there be a mismatched hole count on one side?



Looks like your fulcrum or pivot points on your catapult don’t line up properly. Also avoid using pegs for pivots on high stress applications like the catapult pivot.

I hope that helps.



Seems like the outside mark is the pivot and the inner mark is the choo choo linkage, these wouldn’t line up. Difficult for me to tell in these pictures.

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I agree. It’s difficult to know for sure from the photos. But some of the other photos show a green 1x beam coming from the choo choo into the catapult arm. So I think the central part with the metal axle is the pivot point of the catapult arm. And if that is the case, the outer pivot points don’t line up and will be pulled apart every shot. :thinking:

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