Flywheel too powerful

Sooo me and my first ever competition for our school and it was fun but we have quite a few problems. One being our flywheel. We took our cartridge out and just programmed 3 buttons (y, x, a) to be at 50%, 75%, and 90% power but the 50 was to low and the 75 would overshoot. My knowledge on gear ratios is very questionable. Any suggestions to get the right power for it?

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Somewhere between 50 and 75 should work, but it depends on where your robot is and how much it is overshooting.

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What’s your current gear ratio? Is it direct drive?
Many teams have found a 5:1 600 (60 to 12 tooth, 3000 rpm equivalent) and a direct 3600 on a 3" wheel to work very well.

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Our team shoots a little too much with a 7:1 4200rpm ratio, but it still works.

We can shoot 8-10 feet max and make it consistently if we are aiming right. Just find whatever works best for your team and playing style, and test it.

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Are you sure your flywheel is actually reaching 4200? If it’s a 10 foot max range, I would expect that you aren’t actually reaching full velocity. You could also be using a smaller wheel, but our 3600 rpm 3 inch flywheel consistently shoots full cross field, which is somewhere around 17 ft. Our tests with a 4 inch wheel at the same velocity shot over 25 feet. Well, I guess if it works, don’t fix it.

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How do you get it so far? We have 3000 rpm 4in flex wheel and it shoots 3 ft

We have no way to be sure, but we definitely have some friction problems. I am trying to get ball bearings to fix this.

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Keep in mind that ours is actually faster than 3000 rpm, but not enough to make a difference of 14 feet. I would suggest that you probably aren’t actually reaching 3000 rpm. It’s possible that it’s never reaching the geared ratio due to the motor’s torque limit. We are using a cartridge-less flywheel to actually be able to reach full speed (it eliminates friction from the gearing, thus allowing us to have a one-motor flywheel and a higher top speed). You can see the actual velocity that it reaches, the power usage, fluctuation, and other useful stuff from the brain screen’s ‘devices’ menu. Note: it’s probably better to have a more powerful flywheel that you run slower (we run ours around 20% normally) than a flywheel that has the same top speed as your total intended speed.

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Make sure to reduce friction as much as possible. Also, tinker with compression and different flex wheels.

You don’t have to have ball bearings.

Check your bearings. Turn the shafts by hand. Do they feel ‘notchy’? If so, your bearings are damaged.

Check your shafts, they should be smooth when turned. They might need a light sanding.

Check shaft alignment… turn on the motor using direct brain control. Spin to ~50% speed. Check watts used. Slightly loosen screws holding flywheel assembly together. Wiggle left/right/up/down until watts reads the LOWEST setting and then tighten screws to hold it in that position.

I’d also display motor rpm to the brain… my bet is that you are NOT seeing your desired rpm.

A single motor, geared 1:5, will turn a 4" flywheel at 3k rpm using from 1-2.5 watts of power if constructed WELL.

I’ve got a thread on flywheel quantitative analysis… I’d suggest checking it out.

Also, wheel balance issues matter TREMENDOUSLY.

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We found it is fairly important to tweak fit between the flywheel and the side of the chute when the disc makes contact with the flywheel. If the fit is too loose the flywheel can’t impart much energy. I think we found the width between the flywheel and the side should be between 1/16”-1/8” narrower than the disc itself.

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Hope you wrote up a notebook page on that w/ pics and so on.

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it’s currently direct drive at the moment. we experimented with a ratio but now its a direct drive with no cartridge in it

take the cartridge green cartridge out

We dont have flex wheels so we have to use green wheels. i’m tryingto grt in contact with 2 different schools for parts

The thing is without the cartridge, we can see it and hear it reach max. During our comp, we were known for the crazy strong flywheel

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Just started our notebook late sadly. I’m currently trying to figure out how to input information that we used


sgrunspan

I’m the coach but yes I’ve tried to get my students to document everything. Along with, “are you wearing eye protection?” I think the thing I say four times an hour is ,”document!”
I’m new to VEX, they’re new to everything, and we’re all learning together.
From this picture (HW based design) you can see the space between the flywheel and a strip of poly is too big. We adjust the spacing by moving/sizing the strip.

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We ran into the same issue we ended up reducing the velocity of the flywheel and the indexer