Stand-out mechanically simple Shooting mechanism

Many of the teams I’ve seen on this forum are using things such as catapults and slingshots, but I’m pondering a pretty feasible way to incorporate a more responsive and consistent firing tool.

This idea is quite similar to popular Airsoft-Gun gearboxes. Here is an example of the latter:

Now the idea is practically the same. A motor moves high torque gears to pull back an object (threaded on the bottom to mesh with gears) against a spring and are then let loose to push the object forward. In the airsoft case it would be a cylinder creating mechanically conceived High Pressure Air, but on the robot the object would impact the “boulder” directly and propel it outside the barrel.

I’d like to know your thoughts and if you have any ideas on shooting mechanisms please post in this thread.

Sound like an interesting idea I am a little skeptical as to if the ball will survive an impact like that because they are squishy and our school has had problems with similarly designed balls falling apart.

That is how many teams moved soccer balls in a game not too long ago. Or how ping-pong balls get motivated.

The issue is repeatability: Can you make the ball go to the same place each time? Sounds like it is time for a prototype and some experiments.

Stand-out mechanically simple? The devil is in the details:

  1. how do you design this so that you have the same potential energy every time you pull the “object” back?

  2. how do you hold the object in the armed position once it is pulled back?

  3. how do you fire the object (release it free from the motor and the gears)?

  4. how do you load the bounder into position?

… and so on.

This was a popular choice for many teams, including my team in the 2014 season. As Ether mentioned, the design may seem simple at first, but getting the puncher built in order to work exactly as you want is a challenge.

Here are a couple puncher test shots from our 2014 build season video blooper reel. We labored for hours to get a linear launcher that shot balls from above the assembly rather than from in front of the assembly.

Here it is working from the same video.

It was so difficult to get this working that we had almost scrapped the idea altogether.


I am wondering if it would be possible to use create a similar mechanism using penumatic actuators?

Yes actually, even in the airsoft world some use pnuematic pressure from stored tanks. Most commonly called polar stars to help your search.

I doubt it, in airsoft there’s a mechanism called a “hop up” which pushes down on the bb to generate rotation which then forces the bb to ride the top of the barrel. This is what generates the accuracy of the shot. The softness of the BOULDER would interfere with this or similar mechanism.

Then again, it’s a large enough goal from close enough away that it might not matter.