Is there a difference in using big traction wheels in flywheels compared to smaller ones?
Yes. A flywheel is all just a transfer of energy from the flywheels to the ball. Because the small traction ones have less mass, they cannot store as much energy, meaning that they will slow down more after each shot. The larger wheels have more mass, which means that they can store more energy, meaning they won’t slow down as much after each shot because the total amount of energy they can hold is more than the small wheels but the amount that the ball takes is the same. But because the small wheels can hold less energy they will spin up faster because the motors can fill them up with energy faster. This also means that while the larger wheels will take longer to slow down, they will also take longer to spin up. This is the reason that flywheel weights work. They add more mass to the wheel, making it slow down and spin up slower. Another thing to take into account is the surface speed of the big vs. the small wheels. The surface speed is just how fast the outside of the wheel is spinning. The more mass the wheel has, the more consistent the surface speed is. This is because it takes more work to change the speed of something that has more mass than to change the speed of something that has less mass. So the bigger wheel that has more mass will have a more consistent shot because the surface speed will remain more constant.
So all in all, I would recommend the larger flywheels, but there is some validity in the small ones as well.
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For Bankshot, most of my students used the smaller wheels but with two motors powering them at a 25:1 gear ratio.
There are also the new flywheel weights that you could use to help keep your shots consistent. As they haven’t really been used yet you will just have to try and see what works best.
You could also use the smaller wheels and double them up. You could double up the big ones.
This is the time to figure it out. Build a few shooters. See what works!
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Cool! Thanks a lot to both of you!
@FRC973 I saw that your flywheel robot uses 2 motors for 2 flywheels, are they geared separately or together? Because I was trying a big flywheel with a 1:16 gear ratio connected together, and they go in the same direction lol. Your brother told me yours was a 1:15 as well. Another question, how much does your ball squish to go in between the 2 wheels, because I have a bigger spacing than you, and it refuses to go in(or at least when I was using 3:1). I believe this is why the gear ratio is big…?
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Ours are geared separately, mainly because it only increased the friction and complexity when we tried gearing them together. And since we regulate the RPMs in code, we don’t have to worry about them going different speeds.
Yes this is true. I would recommend this gear ratio.
We have 12 holes (6 inches) of spacing from axle to axle, but I would recommend trying various spacings and seeing what works best for you.
Yes, that is why we used 1:15. We couldn’t get much under ~1:15 to work very well.
The secret behind a flywheel (or any type of robot) is to try as many things as possible. There are many sayings that go along the lines of “If you don’t try you won’t succeed”. That’s because it’s true. One thing that we try to do is to “fail faster”. Because the more you learn, the more you will succeed. Just like Winston Churchill said: “Success is walking from failure to failure with no loss of enthusiasm.”
Good luck on building your flywheel!
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Ok cool! That helps a lot!
It completely failed lol. I did a 1:15 separately connected, and it is SO SLOW, why is this? or do you mean 15:1 @FRC973
15:1 as in motor:output
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This could be because you geared it backwards. Meaning you did a 15:1 instead of a 1:15. So the motor spins 15 times for every one time the flywheel spins.
That is how you would correctly write it. VEX has a great video on gear ratios if you are interested. Here’s a diagram on how to write out a gear ratio:
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So flywheel spins 1 time and the motor spins 15 times?
The other way around.
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ohhhhh ok so this is wrong 
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Yes, it should be reversed.
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@FRC973 I’m so confused on why your robot is able to have a 12 hole space and mines needs over 16 holes is this because you do it vertically and not horizontally?
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Oh yeah that helps thanks
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I finished my flywheel, but I cant send videos 
But @FRC973 It is pretty good, but still cant shoot into high goal, still need to up gear ratio a tiny bit I think? Idk I’ll keep testing
Oh here watch this video
I think its an ok flywheel, now time to make it go higher somehow?
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First, make sure you’re letting it spin up to full speed before putting the ball in. I was able to make it well into the goal with 70 RPM which is not full power (that’s around 80 RPM) with a 1:15 gear ratio, so it theoretically should work.
Another thing that could lower your flywheel speed efficiency and could make it spin slow is friction. The more gears you have the more friction your mechanism will have and the less efficient it will be. You can help with this by minimizing the amount of friction in your gearbox.
Try spinning your flywheels by hand and seeing if there are any places where it has a hard time spinning the shaft. Just for reference when I spin my flywheel by hand, it takes a rotation to spin down from just a quick spin. If it stops immediately and doesn’t spin down when doing this test, that usually means you have too much friction. If you could send a closer up picture I (and other people) could probably provide some more help. I’m looking forward to hearing how it goes.
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Thanks, I will maybe just let the flywheel run on auto for the entire driver period, idk, I have a 1:3 with a 1 on the 3 with a 5 gear connected so 1:3 with 1:5 so it should be 15. I will try to get more photos. Thanks a lot again!