# HELP WITH VEX

Our school doesn’t do Vex, but recently I have had an internship with a school that has. They have asked me for some help. So they have a 10:1 gear ratio, how can they increase the velocity with limited resources? I think that is the biggest their ratio can go.

If you mean VEX EDR then you will find better help on the vexforums.

You will also get more help if you include more information in your post, such as what you are planning, how the gearing is set up, and why the speed needs to be increased. Currently your post is extremely vague and unlikely to garner much useful information.

Have you thought of doing 2 or more reductions to get the higher speed?
You probably want to figure out a gear box using available VEX gears to bring the speed up to whatever you need. Just remember you will be trading speed for torque and the gear box may have more friction than you want so you may not be able to get really high speeds after you apply a load to this system.

Good luck

They can stack the gears.

Lets assume they are driving a 84 tooth gear with a motor, that gear is driving a 12 tooth gear.

If they put a 12 tooth gear on the same shaft as the 84 tooth gear and the drive the new 12 gear with an 84 tooth gear they will get more speed out of it.

Remember, that speed is the inverse of torque, so has the speed goes up, the torque goes down. So while the last 12 tooth gear is spinning pretty fast, it won’t have a lot of power.

Is this ratio part of the drive train, or part of a"shooter", or part of something else?

There isn’t actually a way to get a 10:1 ratio in Vex with just gears. You can only get combinations of 1, 3, 5, and 7 (12, 36, 60, 84).

I’ve heard as a rule of thumb, a good ratio for 4" wheels on both sides of the ball with 2 motors per wheel is 49:3, which can be achieved with a 12:84 and a 36:84 gearset.

Two stage 10:1 gearbox with Vex gears is no issue…

With a 12 tooth CIM gear.
48 and 20 on a lay shaft. CIM drives the 48, 20 drives the 50 on the output shaft.

(48/12)(50/20)=10:1

Replacing the 48 gear with a 44, 42, 40, or 36 would reduce the gear ratio and provide faster velocity and lower torque.

Just as a point of clarity, VEX could commonly refer to any one of the following:
-VEX Robotics (division of IFI)
-VEX Robotics Competition (VRC) (robot competition using VEX EDR and IQ robots)
-VEX IQ (robot parts series designed for the same market as LEGO Mindstorms/FLL)
-VEX EDR (robot parts series designed for the same target age as FTC–the original FTC kit…)
-VEXPro (robot parts series designed for FRC)

From the context, you’re referring to VEXPro, while the OP is referring to one of the other items on the list, likely VRC or VEX EDR (or both, given that VEX EDR is used in VRC). CIMs don’t work very well with the EDR line.

Minor correction. The VEX Robotics Competition specifically refers to a robotics competition for middle and high school students using VEX EDR parts. The VEX IQ Challenge is a robotics competition for elementary and middle school students using VEX IQ parts.