DR4B Gear Ratios & Skills for Tower Takover

Hey, I pretty new to vex and for this year, I was planning on building a DR4B reverse stacker. I didn’t use V5 last year so I was wondering if a 1:5 gear ratio with a 200 rpm motor would have sufficient torque for my lift. If 200 rpm on 1:5 ration is not feasible torque-wise, how slow would the 100 rpm 1:5 gear ratio be for the lift, as I’m reluctant to change the gear ration to 1:7. Also as a side note, are we allowed to score on the other alliance’s goals and the other alliance’s towers to contribute to our driver and program skills scores like was done in ITZ?

I recommend using the high torque motor cartridges for your motors but I’m not sure about the ratio. Yes you can score in all zones for skills.

I’ve heard 1:7 is generally the best.
Although if you were super good about it, you could get a 1: 5

Could you explain the “super good”? I’m assuming you are saying this with a 100 rpm motor. Do you mean making the lift as light as possible?

like enothecool and Railgunawesome said, I would suggest using a torque 100 RPM motor with a 1:7 gear ratio. The 1:5 has good torque but a 1:7 has the most torque, and I have seen has worked the best. Why would you be reluctant to change the gear ratio? Do you not have enough room for the big 84 tooth gear? For skills I am not sure.

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I’m reluctant to change to 1:7 gear ratio because of the slower speeds, I would like my lift to be as fast as possible with reasonable torque.

Cubes are heavy this year, so you will probably want a 7:1 ratio. This is a video of our lift going up using 100RPM cartridges and a 7:1 ratio.
com-video-to-gif

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That’s actually pretty fast. Thanks for your input.

The speeds should not slow down much, and I personally think that a slightly slower speed is better for a DR4B because you will need precision to stack on preexisting stacks.

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Oof. I just checked and I don’t have enough space for a 1:7 gear ratio. what are the problems with a 1:5 ratio. It seems like adequate rubber banding will make up for less torque.

When in doubt, stability and consistency should always come first before speed. In the Zone was really the main game where having a fast lift speed seemed smart as you could only lift up one game object at a time, but given that you can lift multiple this year, you truly need a higher torque lift to be able to handle a higher load.

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Why don’t you have enough space? Back when we had our intake on the bot, our lift couldn’t hold much more than ~7-8 cubes up on its own. We filled the bottom triangles with rubber bands and have 4 doubled up bands on each side of the 8 bar. Depending on how big your lift is and how heavy your intake is, this might not be a problem, but switch to 84 tooth gears if possible.

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Yes, you can use all the goal zones and towers in skills.

1:7 is still pretty fast, and has the best strength. but 1:5 will still work, as long as you aren’t picking up too many cubes at once. rubber bands help.

also, @Anomalocaris is that a dr4b/8b I see? why 8 bar? why not dr6b?

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Thanks, I think I figured a way for a 1:7 gear ratio

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1:7 will be my favour. i have a pretty heavy cage so i use the red motor cartridge, even that alone will not work. i put a ton of rubber bands on my lift, and so i can basically counteract gravity.

I believe if the DR4B is well built you should be able to get around 4 cubes well, maybe five on a 1:5 lift with 100RPM cartridges. I don’t recommend 200RPM at 1:5 though, I think that’d be pushing it, but some people have pulled off some pretty cool stuff. Are you using a single motor? If so I would definitely stay away from using a 1:5 gear ration on 200RPM.

i use 100rpm. we have a heavy cage that can lift 5 cubes. so we need like 60 rubber bands to make it work. if it doesn’t work, “double the bands”

That can backfire to a point. Too many rubber bands can cause it to struggle on going down. The goal is to get the lift to the point that gravity doesn’t affect it.

It is indeed an dr4b/8b. We used it over a 6 bar because we had limited horizontal space in which to build it (referring to front-back axis), and intending to be able to stack on top of 6 (ideally 12 each cycle), we had to take every measure possible to avoid tipping, so we figured that if we purposely made the lift tall enough to stack about 5 cubes higher than needed, the weight of the lift would not be shifted all the way forward and we could move the intake out at max speed without having to worry about knocking the stack over and possibly falling out of the field. Though it definitely helped, however, it did not solve the problem, hence why we abandoned the bot for the time being.

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