HELP! Ball wont shoot out the top of snail bot

So my ‘Snail bot’ has this problem where when it comes to shoot it out of the top it just doesn’t work.
No matter what I try by changing the gear ratio or increasing traction it seems to just barley roll out, not even close to shooting the ball up into the goal!

Does anybody know how to fix this or what you did to make your bot work?

here is some footage of it.


If any body can give me any help please do, I would really appreciate it,
Thank you!

It looks like your hood might be pushing the ball down. Also, what rpm are you running?

Are we able to get a side pic of your robot? The track’s path might be messing it up


The 2 back rollers are geared to a 1 to 1 ratio with a 600 rpm motor and the 2 front ones are powered by a 200 rpm motor but the top roller is geared up 1 to 5

Here are some more photos,

20210410_145826 20210410_145733 20210410_145738 20210410_145800 20210410_145811 20210410_145820

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I think you might be having a compression issue. If the ball isn’t being gripped well by your rollers, it’s going to have a hard time going up. Maybe try tinkering with the size of your sprockets/gears to see if that solves the problem.


So, a couple of things:
-You will not be able to “Poop” the ball out the back with how they are chained, and you may want to brace the sides of your x-drive.
-It looks like you have way too much compression on the ball throughout the rollers- I would recommend moving either the front or back roller towers a few more holes apart, or using smaller rollers.

-The speed of your top roller needs to be launching the ball, not compression. While compression will work, it has a slower speed and will be less efficient. I would recommend changing the gearing to somewhere around 1200-2000, and making sure there is little friction.
I would take a look at these threads:
Help: Snailbot isn’t shooting ball up
Snailbot issues
Here is our bot, Sorry about the kinda bad quality gif.


your rollers are moving incredibly slowly.

and I can see you have a 30 tooth to 6 tooth sprocket ratio powering that top roller, so regardless of what motor cartridge your using, that roller should be spinning so much faster.

either you have a ton of friction and your motors are stalling, or you’ve set your motor speed very low in your code.


Can you check to see the speed your rollers are running at? They seem to be moving quite slow (what xenon said) although this could just be because of the camera


You are right! I drove my robot while looking at the motor in devices and it said the velocity was about 30%


My team actually had this problem before, that when the balls come to the top, it wouldn’t shoot into the goal. So what we did was we put the rubber bands in a position, that instead of the hood going up, stayed down. This worked because the downward pressure coming from the rubber bands helped push the balls outwards.

I am not sure, if that made sense, but here is a test video of my team’s robot:

You can see the rubberband at work, forcing the hood downwards, once the ball is shot out


I modified the robot a bit and this is where we are at now.

The ball just isn’t getting any height, the top roller is at 1000 rpm. I could chance making it 3000 rpm but that might be two fast.

Any suggestions on what I can do now?

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It looks like it might be an issue with the hood. You don’t need to go any fast to make it work. Our top roller is 900 rpm and it works fine. Your hood gets nicked back by the ball. Try holding it and moving it to different angles.


We tried moving the hood at all different angles and while it shoot out it we were never able to get it to shoot up into the goal.

We had a different roller geometries, but around a 30 degree angle worked for us. Other option is to try removing the anti slip mat from the top and see if that helps

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We just tried it without the anti slip mat and its still not working.

How tall is your top roller? If you can, move it up a hole or a half.

How many rollers are you running off that one motor? And let us know which ones they are.

the top of the top roller is 17 and 3/4 inches.

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Front rollers = 2 rollers powered by a green motor geared 1 : 5 . The back rollers = 2 rollers geared 1 :1 using a blue motor.