Slip Gear Catapult For Spin Up

Hello vex community, I am very new to the robotics world and was wondering if I can get any help building a slip gear catapult. Does anybody know where to go for a step by step tutorial or have one themselves they can share? Thank you vex community


Hope this helps!


This was our cata a few weeks ago. I don’t have any recent pictures focusing on the gears, but in terms of the way the gears are are arranged, not much has changed.

Motor shaft goes to pinion. Pinion goes with unshaved gear. On the same shaft as this gear there is a gear shaved with a file. This is aligned with the gear that the arm is attached to. Make sure to use high strengh everything.

Also, make sure you know the angle you want the catapult to go down to before shaving. We overshaved the first time, but we needed the arm to go even lower to make it easier to intake.

I am also pretty new and this is my first post, so I am not very good at describing stuff.


Did you mean actual catapult or using it as another name for the puncher?

There were many design discussions regarding catapults in the past seasons:


What’s the point of the uncut gear?

It connects the motor shaft to the slip gear shaft. If this wasn’t done, the slip gear would lose connection with the motor shaft.


I have a similar set up but I can’t get the teeth cut of right how many teeth do you have left on your slip gear

You should decide this for yourself depending on how far you want to pull your catapult back. Here is a formula:

Let x be the amount of unshaven teeth in a sequence, y is the gear being driven, and z is the angle in degrees pulled back then:
(x/y) * 360 = z
For example, we have 21 unshaven teeth to an 84T gear, which pulls our catapult back 90 degrees. We shaved 9 teeth off of both sides of a 60T gear.
Experiment with your own choices and notebook it. The only recommendation I will give you is to start out by shaving only a few teeth, and slowly shave more if needed. This way, you won’t burn out of multiple gears.


Ok thanks for the info I will do some math and figure it out