Spinning an axle without direct power/linkage

(basically giving away my robot plan in separate topics, but anyway)

I have an idea that requires a spinning axle very close to the ground, so close that I wouldn’t be able to power it from a motor, or with the smallest gear/sprocket so there’s no way to externally power it to spin.

Do you guys have any idea how to spin that axle consistently?

I’ve had some ideas:
String connected to a separate powered axle, that when the powered axle spins, the rope unravels and spins the unpowered axle. Issue with this is longevity. I’d have to have a long enough string to be able to unravel for basically the whole match (or at least a very long period) and then after each game I’d have to reroll it up, which isn’t really a good plan.
Using a traction or flex wheel on a powered axle pressed against the unpowered axle, using friction to spin the axle. Issue is the uneven shape of the axle, which could lead to uneven spinning (could be solved with sanding, but idk yet) and slipping, since this spinning unpowered axle needs a bit of torque to fulfil its purpose (not giving that away, but its kinda obvious I think) and with only the friction of a traction or flex wheel, I feel like it could slip and not be useful.

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if you tell us what you’re doing that requires a shaft being so close to the ground that not even a 12t gear will fit on it might better help us help you, otherwise it’s difficult to know what you’re trying to do here.


Alright, it’s to help the intake.

I watched that Wolfpack machina video and one of the things they had in their disc intake was a spinning roller close to the ground to help “kick” discs up in their intake.

I wanted to try something similar to that.

Honestly I could probably use a 12t gear and be fine with the axle slightly off the ground and spinning, however if it’s possible to have that axle spinning and as close to the ground as is possible, I’d like to give that a try first, before going with the easier and ngl probably better option

Quick edit: Also with the way I plan to build my intake, I don’t know if using gears is feasible, meaning I’d have to use the small sprocket, which iirc is a little larger and with chain I think it would be larger than ideal

I know exactly what you mean by this description, the deformation of the discs should allow it so you don’t need the kicker wheels/spinners, but I understand that want for one. a 12t gear will give you more than enough space for the kicker wheel to be effective and powered, then again, there’s always chain if your mechanism cannot use gears. such as chain and sprocket from motor to a separate 12t gear connected to the needed to be powered 12t gear. such as this

if you want to have a pickup roller on the underside of the intake, just the rollers on it will likely need to be larger in diameter than a 12t gear, meaning one should be able to fit just fine.

But already people have been making intakes that work very well without any sort of underside roller, so this might not actually be very beneficial. Don’t let that stop you from trying it out though.


The way I was initially planning it was just a bare axle very close to the ground that helps to kick the discs into the intake. So no extra rollers, just the axle that goes under the bevel of the discs and kicks it into the intake.

I do see that intakes work fine without that small pickup roller, however I feel like I would like to test this to see if it works well, also I don’t completely trust my own building to have a consistent plastic only intake base, so a pickup roller may assist me to be a little more consistent with the intake

Also I don’t even have anything to test with yet, this is all still theory crafting of possible robot ideas, I’m sure that when I actually raise the money and get things, testing what actually works and doesn’t is a lot more beneficial than just thinking of what I would like

is it possible to make a small gear out of plastic? that could work

I could try a custom gear from stacked plastic, but i don’t have experience with doing that, and at that point, 12t gears are fairly small, I might as well use those over making custom gears


I love this idea! It sounds like something I would chase after, whether it is actually a good idea or not. Please keep us posted on your progress and experimentation!
Maybe a universal joint would work. If you or your organization don’t have any, you can find them here on the VEX website - $11, VRC legal, and in stock!

OR, perhaps you could use a 12t to keep in familiar territory, but line the whole axle roller with 12t gears. This might aid in lifting the discs upwards because of the teeth.

Edit: Watch out for these low goal barriers!!! They could potentially wreak havoc on low clearance mechanisms.


I will probably end up using 12t gears, theyre fairly small and should be fine as a pickup roller.

Those discs against the barrier will be fine, I have an idea for a workaround avoiding the barrier entirely, while still picking up those discs