Vex Spin Up Endgame Expansion | 67101C

It is not that dangerous because the string will do nothing to you and the weight on the end does/will not have to weigh that much. Most teams also plan to shoot inside of field and have measured out how much string to use to make sure that it does not fall out of the field. Some teams have also made a spot for endgame to maximize their amount of points and they have measured that so it does not fall out of the field. At the end if you get hit then there will be very little to no harm done.


where do you buy the string? is it VEX compliant?

Any string less than 1/4" diameter is vex compliant

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what object do you put at the tip of the string so it has weigh to pull the string away as far as possible when shooting? I mean what type of object will be VEX compliant? for example can I shoot out one of the wheel and attach the tip of string to it?

Try it and see, and document the process in your engineering notebook.

Any vex part that falls under R6(h) would work as the projectile.

This would work. Just make sure the string diameter is under 1/4 of an inch.


We don’t have access to pneumatics, and with 4 motor drive, 2 motor flywheel, 1 motor indexer, and 1 motor intake, do you have any advice on how to still make a similar system?

It should be possible to have the endgame triggered by a ratchet running off of your flywheel or your indexer since these mechanisms should only be going 1 direction during normal gameplay.


You’ll have to use some form of motor sharing, look at some of these links:

Our experience with Ratchet Mechanisms in Change Up (62X)
VEX Ratchet Tutorial
315G Ratchets Explained (6 motor drive, 2 motors for everything else)
Smallest vex ratchet

Vex Differentials Explained
Differential transmission - power takeoff from the drivetrain motors
Differentials —“Some help from my fellow SCA member”
Differential Concept
Please share some examples to understand Differential & Bevel Gear Pack use case for vexiq


Provided that it is at least 1/8” in diameter or larger, as per the new game manual update.

On that note, I should point out this entire mechanism is now illegal: it uses yarn that is 3/32 inches. Something like this is certainly still possible with thicker string though.


1/8" to 1/4" is the specification for legal diameter…

just to be clear.

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Yes, which people would know if they saw the post I had replied to (or read the game manual + update, for that matter).


Thanks for the tips! I will go through these links, and try to find a solution.

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Yes I think I will use the indexer. I was planning the expansion device to be right under the flywheel anyway, so I think it would work out well. Thanks for the help!

I’ve looked through all of these links, and although both seem very confuzing, the differentials have me confuzed most, so I am going to go with rachets.

Rachets are the simplest, so you might as well. Sometimes the simplest solution is best (and almost certainly most reliable!)


You guys have been asking for this for a while. Here is an explanation for our endgame expansion mechanism. We used it with extreme sucsses at both Haunted and a Nebraska event. This endgame typically scored 70+ points and it got a max of 78 in competition. Our lowest score in a tournament for expansion points was 60. Feel free to ask any queations.


How do you have the expansion not shoot outside of the field?

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Well, it’s on the front of the robot so we can assume it won’t be going out the back, and for across the field, they probably just limited the string length.

As simple as a design this is, I made one of these to test and compared it to standard launchers I see at competitions. This one worked way better and I was able to put more of these on while using less pistons/ motors, works with both.