# Catapult bots how did you do the slip Gear

my team and I are building a catapult bot and we don’t know how some teams achieved their slip gears we’ve looked and can not find them online anywhere

Here is some information: slip gear

For us we just used a dremel or a saw to cut off tooths on a gear in order for it to achieve slip, The amount of slip needed is different from every team so there won’t be any pre-made slip gears online but rather DIY slipgears.

This comment gives a bit more in-depth explanation: slip gear - #3 by AppleDavidJeans

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Kepler Electronics has a good video in it. Post-Worlds Catapult Reveal and Explanation - YouTube

For the fabrication of the slip gear itself, I found that the belt sander worked best.
The typical gear ratio is 12t driven:36t slip:84t mounted to the catapult
You can find the number of teeth you need by measuring the catapult angle range, multiplying it by 7/3 to account for the gear ratio, dividing that by 360 to get the percent of the gear you’ll be using, then multiplying that by 36 to get the number of teeth you need (or just multiply the catapult angle by 7/30). You’ll want to round this down if you get a decimal. Then simply shave off the remaining teeth.

For the implementation, you’ll generally have 3 axles:
Axle 1: 1 or 2 12t gear(s) going 100RPM.
Axle 2: 1 or 2 36t gear(s) (nonslip) engaged with the 12t gear(s) and your 2 36t slip gears engaged with the 84t catapult gears.
Axle 3: this is the axle your catapult is mounted on.
All of these axles must be high strength, or they will bend.

This is probably a lot more info than you need, but just in case, here you go.
Good luck, and happy vexing.

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Are you using IQ parts or VRC/V5?

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We are using VRC 5

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We only have the slip gear axle high strength, catapult can be screw jointed and motor can be low strength.

This works great for plastic slip gears but if you want to make a 24 tooth or 12 tooth metal slip gear an angle grinder has worked the best for me.

Here you go :)) it explains everything you need to know.

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You cut the teeth off yourself, then sand it down.

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