I need help. My competition is on the 25th and I do not have a working robot. I have had a month to build, I have started my own team with out school involvement and received enough sponsorship to build a robot. Three months ago I was in a moped wreck and lost half of my right leg. Dealing with that, I have still managed to create a team. It is just me on the team. I have been working non-stop to create a robot, but its not working.

My lift is not strong enough to lift the scoop and a star, let alone a cube.

Can anyone help me?


Your lift ratio is too fast. Try putting a 12t gear on the motors. Also, less gears will reduce friction. Maybe have the motors on a 12t gear go directly to the lift on the 84t gear.

I would change the gear ratio to be higher (replace the input 36t gears with 12t gears) and move the motors to directly below the 84t gear.

Got ninja’d, darn.

You should also use bearings to reduce friction.

Also, if the motor speed is turbo, you could theoretically change the motor speed to fast or torque, but try bearings and changing the gear ratio first.

I am using normal motors. I will try changing the gear ratio and adding bearing first.

Definatley add bearings, I can’t imagine what your friction looks like right now (it can’t be pretty).

Also, as everyone else has said reduce # of gears, but increase gear ratio. No need to use a 5-wide C-Channel on the tower, it just adds weight and decreases chassis speed (which is pretty important in every vex competition). I included a picture I had on my computer of a gear train, which worked fine good at a prior tournament I attended. Motors on the 12 tooth gears, rapidly scaling to a 84 tooth gear for connecting the arm.

In this event, running multiple gears off of the same shaft in my opinion is a must. You don’t have a ton of space to stretch out, plus you add friction and increase the number of places something can break the bigger your gear train is.

If you are having a difficult time lifting groups of stars and/or cubes, you could see what effect a handful of #64 rubber bands would have. I would suggest running between 2-4 rubber bands on each side of your arm, and connecting them down to your chassis. Even just a few rubber bands pack quite a punch when stretched out far enough, you just have to find the perfect space so you get the power without breaking them.

Final Note, I encourage you to look at a claw as opposed to an arm. On the first functioning robot our team had this year, the arm we had (similar to yours) was far less effective at picking them up. If you have time, I think creating a claw would be a pretty high priority. I included a few images of one I saw at a tournament (from team 1460A) yesterday which I really like & am planning on implementing to our robot design before states :slight_smile:

Best of luck at your tournament,

No need for so many idler gears, and especially if you aren’t using bearing flats. Those towers need more support between them; it looks like they’re closer at the top than at the bottom. Finally that shaft at the top is almost guaranteed to twist under load; you need to screw the lift arms directly to the driven gears (84 tooth gear here) and respace the towers to fit.

Screw the lift c channels directly onto the gears. Your axels will twist like crazy with your setup. Also, remove all the idler gears. It causes unnecessary friction, making it harder to lift things. As for a gear ratio, I would recommend a 1:5 (12 tooth gear on a 60 tooth gear) using regular motors. However, if you add 2 more motors to your lift, as you are only using 8 motors in total, I would recommend a 1:5 gear ratio with speed motors. Add bearings (the little black things) to make your lift more stable. Finally, if you are still having trouble lifting things, try adding rubber bands to the lift for some assist. You can find some images online for clarification or just look through the forum. If you are running out of time because of your tournament in 3 days you can dm me for some more tips.

What do you mean by, “Screw the lift 6 channels directly onto the gears.”?

If you look at the pictures @West_ posted, you can see that the lift c-channel is screwed directly into the gears rather than powered through a shaft like you had it.

Sorry, I put a 6 instead of a c. It is fixed now

Oh! I see!

Also, make sure your tower structure are parallel. The right side is narrower at the top than the bottom. This will allow better shaft alignment so you do not lose so much energy to friction.

good luck!

Thank you Everyone. I have made a working robot with your advice.

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