What should I use for a drivetrain?

Programming Support VEXcode V5 Tech Support
1

Hey guys, I have a question? Is it okay to use blue motors as my drive train that is going to be able to hold 2 mobile goals?

2

Will you gear it down? also how many motors? It seems like a bad idea

3

You most definitely shouldn’t. If you are going after speed, you should use normal green cartridges but gear them up slightly. A good ratio would probably be a 6 motor 5:3.

4

if you are doing blue, some ratios would include

  • 257 RPM (effective 257 rpm) (4 600 rpm motors, powered 36t gear → 84 tooth gear on wheel, 4in wheels)

  • 360 RPM (effective 290 rpm) (6 600 rpm motors, powered 36t gear → 60 tooth gear on wheel, 3.25in wheels)

  • 600 RPM (effective 400 rpm) !not advised! ( 8 600 rpm motors, powered directly or through a 1:1 gear ratio, 2.75in wheels)

these are all the really good 600 rpm motor ratios

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5

This is bad advice. Use blue when you can. Less friction compared to green cartridges just gear down

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6

there’s also 400 on 3.25", (48:72) though that is pushing it slightly, even with 6m.

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7

Just my opinion. In my experience blue motors aren’t usually the best option but they can still definitely be used.

8

regardless of opinion, gearing down 600 rpm cartridges is just objectively better than gearing up 200. Because you’re gearing down from 600, you are reducing the slop inherent in the motors instead of amplifying it, and 600rpm cartridges also use fewer gears than 200 or 100, and so have less friction, giving your drive higher efficiency overall.

The difference isn’t big enough to make 200 rpm cartridges bad in the slightest though, and you can still use them with good results. Just that I would recommend using 600 when you can to get these very slight advantages.

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9

Never really thought about the slight difference. I wasn’t saying you were wrong by any means, thanks.

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10

of course using 600 rpm cartridges directly is in almost all cases, not going to work out. The only instances it will is with 2.75" wheels, on a very light robot, with a 6 or 8 motor drive.

If you aren’t super confident with complicated gear ratios and drive speeds, you can never go wrong with direct drive 200 rpm on 4" wheels. It’s not terribly fast, especially for this game, but it’s very easy to get working for newer teams.

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11

correct

(off topic but where’s that 3.25 traction wheel tutorial? :eyes:)

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12

I second this. My robot is using a 6 motor 1:1 ratio with 2.75 inch omnis, which is PUSHING IT, but is totally doable with good build quality.

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13

Can I use 2 green motors and 2 blue motors, will that work?

14

you would have to make them the same ratio, which is relatively difficult, so probably not

15

also do you only have 2 blue motors?

16

You could IN THEORY set the blues to 33.3% speed, but that decreases torque and is objectively worse than 4 greens

17

Yeah, I only have 2 blue motors

18

in that case, just go with a green motor drivetrain, 2 is not enough

19

You can use these for something else like an intake

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20

Please stop using random categories, like programming support. This would go under v5 technical support, or just V5 general.

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