My team doesn’t have access to the VEX parts until school starts (next Monday for us), so I haven’t had the chance to do any physical prototyping. I am hoping that the teams who have already begun building would assist me in answering my questions which will help expedite the planning and building phases of our team’s robot to compensate for the time lost in preparation for the season.

[INDENT]•What are the best wheels to use for the flywheel?

•What are the benefits of using that wheel as opposed to others?

•How much space should there be between the flywheels?

•How many motors should the flywheel (2 wheels) have?

•What is your ideal gear ratio?

•What is your ideal angle to shoot the ball?

•Any other tips/advice to build a successful flywheel system?[/INDENT]

I apologize if I inconvenience you by asking so many questions, but I would greatly appreciate any and all help regarding this subject that you can provide.

1. that is really subjective, you totally want to use traction wheels, but the size is kind of up to you, my team uses the 5 in traction wheels, there are 2 reasons for this, first a larger wheel diameter means the outer edge of the wheel is moving faster when compared to a smaller wheel, second, the 5 in wheel has more mass, and because fly wheels operate in large part on momentum of the wheels a wheel with more mass has more momentum when compared to a lighter wheel going the same speed, we also wrapped our wheels in rubber band, this makes the wheels more tractiony, heavier, and slightly larger

2. again kind of up to you, you want to compress the ball, and there is a fine balance to be struck here, if you don’t compress it enough you wont get enough contact to accelerate the ball, but if you compress it too much you will loose speed to friction the ideal my team has found is slightly less then 3.5 in apart, so we place the wheels so that they are 3.5 in apart, the wrapped them in rubber bands probably for a total increase of .25 in between the wheels, so I guess my answer is 3.25 in apart, but there is no way to do that with normal wheels

3. between 2 - 4 motors , more motors on the shooter will be better for the shooter, but you may want those motors for something, my team has 4 motors, if you can make it work well with 2, I say go for it

4. we are using 4 speed motors(1:1.6 internal gearing) and 1:21 external gearing, keep in mind we use 5 in wheels so the ratio you want may change with wheel size

5. again this is up to you, there is no best angle, all angles have pros and cons, 45 degrees will give you the best distance, but you wont be able to shoot over obstacles and you will have to make most of your goals by bouncing them off the back of the net, also if your angle is not adjustable, a lower higher angle will let you make shots closer to the goal, high angles use more energy, but you can shooter over stuff, and your shots will more drop into the goal instead of bounce, my team uses a 60 degree angle

advice: build well, take a lot of time to build a really good frame an gear box for your shooter. friction will KILL you here so be very carefull, do not cut any corners, use bearing flats, use spacer, use locknuts, take your time and make this part of your build very solid , if parts are loose or vibrate or rub or flex you will curse your shooter to failure

1. Probably the 5’’ wheels. But my team has found success with the standard 4’’ wheels that come with the Clawbot because they are pretty solidly built. We don’t have access to 5’’ wheels.

2. I believe the axles of our 4’’ wheels were 15 holes apart inclusively.

3. Either 2 or 4 work. We have found 4 to be more reliable and consistant though.

4. We used 3:49 for 4" wheels.

5. The angle is whatever your testing of your flywheel tells you. It all depends on how efficient your flywheel turns out.

The biggest piece of advice is to check your bearings. It is so difficult to get the bearings exactly lined up and if its not the axle will rub against the metal and then you have a slower, less efficient, unbalanced flywheel. Do lots of testing, and try to make sure whatever puts the ball into the flywheel during testing (probably your hand), is consistant because that will alter the launching. Also build a sturdy frame because that will focus the energy into the flywheel better.

I have a couple of questions too. First, how do you use 4 motors and not have them conflict with each other. I’ll repost my flywheel so that you can see my set up, but people were saying that I can’t place motors up my gear chain.

Second, how do you get a 3:41 gear ratio?

you have to attach the motors at the beginning of the gear train together using two of the same sized gears. So for a 49:1 ratio it would be a 7 gear > 7 gear > 1 gear > 7* compound > 1 gear

Not necessarily as you could replace the 7 gear with a smaller gear and have the same gear ratio as it acts as an idler gear, therefore saving room e.g.

7 gear > 3 gear > 1 gear > 7* compound > 1 gear

Quote me if I am wrong

that would mean there would be a gear difference between the two motors if one is attached to a 3 and the other is attached to the 7. any motor to motor connect must have the same gear size. otherwise the ratio will not allow one to contribute any work

So if there is a gear ratio on the two motors, then it has the same effects as a single motor?

Well it will probably be worse. The motor that is geared higher would do most of the work and waste energy spinning the lower geared motor. The lower geared motor would be at free speed and still not able to spin as fast as the axle would have spun without a motor there.

Gear your motors together before you gear them to a system. The best way to do the 49 ratio would be

``````Motor  Motor
36      36
84       12
84        12
flywheel``````

Wouldn’t putting a 36 tooth next to an 84 tooth slow it down?

I think the 84 would have to be clustered yo the 36

I would go, 84 to 84 (these are attached to your motors, then go to a 12 tooth, then on the same shat is another 84 tooth, this one attaches to a 36 tooth

I realized the formatting didn’t actually post correctly. Forum thought I typed 10 spaces in a row for no reason. (facepalm) Putting them in code tags fixed it.

I understand now

Thanks people. I was so frustrated trying to figure this out. Between my 7 year old motors and the ones we fried last year attempting skyrise, i couldn’t figure out if it’s a design flaw or the motors. It was most likely both : )

Yep, you want to keep the gears on the motors the same size.

Maybe the ratio applies to the third axel?

What do you mean?

The motor with the 36 & 84 gear affects the third axel with the 12 and not the first.

This may help.

Not quite the same but you can see two motors with 36 tooth gears at the top right of the picture (ignore the third motor). They both then drive a 60 tooth gear that in turn drives a 12 tooth gear.