My team is starting to begin to think of ideas for endgame and we want to build string launchers. We aren’t totally sure on how to build these yet. and are looking for a little bit of help. thanks to whoever responds.
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Most that ive seen involve a tension based launcher that releases via pneumatics or a motor. You should be able to get started brainstorming and prototyping based on that, or from the various other posts related to this on the forums.
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YouTube has a lot of good ideas for string launchers
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I was thinking about this too, and this is what I came up with:
- Wrap a ball in string
- Tie the string to some point on the robot
- Create some type of box to hold the ball during the game on the bot
- Use Pneumatics to launch the ball
Basic outline, but I hope this helps!
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@9MotorGang started a thread here:Vex Spin Up Endgame Expansion | 67101C. I found it to be quite helpful, although I must confess that I haven’t tried it yet.
PS: Welcome to the forum! 
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it does i have been trying to find some but i wasn’t able to find any. with just like showing or talking about it only in reveals.
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If you are looking for some sort of step-by-step directions, it’s highly unlikely that any team will share such detailed plans with you. I would encourage beginning teams to build one of the pre-designed trainers, found here: V5 Build Instructions - Downloads - V5 - VEX Robotics . These pre-designed trainer-builds represent generally good-quality building techniques (especially the “V5 Clawbot”) so you can learn the VEX building system. Each season, a new pre-designed game-specific trainer is offered (this year it is called Disco) to provide a starting point for teams to compete in early competition: typically a robot with good build quality but deliberately mediocre game performance. Once you have become familiar with the VEX building system, you can begin to look at pictures, youtube videos, game reveals, etc, for inspiration, then work through the engineering design process to build your own unique mechanism.
VEX has a great resource for beginning teams to learn the design process and how to make decisions. Take a look here, and especially look at the “engineering” section to see how experienced teams have worked through making their design decisions: https://kb.roboticseducation.org/hc/en-us/articles/8373753632407-Students-Start-Here
and:
https://kb.roboticseducation.org/hc/en-us/articles/4460497609751-VRC-Engineering-Design-Process
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What exactly do you use as the ball?
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You can use any VEX-legal component…see rules R6 and R7 in the game manual. Do some design work yourself and document your progress in your engineering notebook.
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Thats what I was thinking! Intake rollers could be a good one…
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yes we have a mini catapult based launcher but we aren’t sure on how to release it with a motor as we don’t have pneumatics available.
Any help will be appreciated.
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How about a simple structure lock, or a slip gear mechanism, or ______ ( you come up with that last one )
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what is a structure lock?
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we do have a mechanism idea where you pull a shaft out and the launcher releases but the shaft pull needs to be connected to a motor that is going to pull it out somehow,.
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essentially what a structure lock is. Just something to hold it in place until the structure is moved.
also, the fun part about vex is innovation! figure out how to move it using other references. 
glhf!
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Sounds like a good concept. So now you should be thinking: how do i use the motor’s rotary motion to move an axle linearly? as has been mentioned ad nauseam at this point, do your own design and prototyping. No one here will hand you a blueprint of how to design your specific launcher.
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Keep in mind that any launcher is only good for 1 event. After that, all teams present w/ be copying the best design they saw.
It’s an arms race…
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Not necessarily. Teams can even take a close look at my launcher and that won’t give then all the secrets, just a head start. A ton of time still goes into tuning the amount of string necessary, the speed of each launcher, where the launcher is on the bot, launch angle, and making sure it is safe and doesn’t leave the field.
That’s like saying any flywheel is only good for 1 event.
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A flywheel is a known design… not particularly hard to build. The string launcher… something new, and people aren’t even decided on launch angle, retention method, release method, string length, and other trade secrets.
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One thing I would like to add is make sure there are no accidental releases.
Ensuring the design is 100% fail safe will ensure that you don’t get DQ’d or disabled early.
It’s very disheartening to just sit in a corner and wait the match out because the robot expanded early.
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