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-   -   [FTC]: 4 Stage Gear Train HELP! (http://www.chiefdelphi.com/forums/showthread.php?t=83297)

HAL3019 21-02-2010 16:53
[FTC]: 4 Stage Gear Train HELP!
 
In order to propel the balls we created a 4 step train.

(=) is bound to, (->) is meshed to

120 -> 40=120 -> 40=80->40=80 -> 40 This multiplies our output speed by 36 times (5544 rpm).

This worked great until recently when it hung and the motor began smoking.
Now on our 3rd new motor we need some serious help; how can we modify this so that it will actually spin down the train. When the power switch is thrown the motor twitches and hangs.

Thank you all in advance,
HAL

Abra Cadabra IV 22-02-2010 19:39
Re: [FTC]: 4 Stage Gear Train HELP!
 
:yikes: That is certainly VERY fast. Oh my.

It depends on what kind of launcher you're using, but you can probably just take out the last stage entirely, which should leave you with a much more manageable 1:18 ratio. As far as I'm aware, at max power that's coming close to the height and distance limits on launched balls anyway.

(Personally, while using a wheeled pitching system my team's never felt the need to go beyond 1:9, and did very well at several competitions using 1:6. Really depends on launch angle and spacing between the wheels, though.)

There's a couple of posts here on the issue if you look back a couple months. This one in particular talks about the necessary speeds for certain designs as well as the safety aspect of running things that fast: http://www.chiefdelphi.com/forums/sh...ad.php?t=78880

buddyb 24-02-2010 15:33
Re: [FTC]: 4 Stage Gear Train HELP!
 
I agree with Abra. Our team uses 1:9, and it serves us really well. 1:36 seems like a bit much.

If you need to retain your current ratio, though, try code like this (pseudocode; will not compile in anything; you need to run this as a separate task, or integrate it in to your main loop such that it is executed without an explicit wait)
Code:
//5 for all of the values is arbitrary. For faster revving, go with 10 or so.
IF(abs(motor_power - desired_motor_power) < 5)
    motor_power = desired_motor_power;
ELSE IF(motor_power > desired_motor_power)
    motor_power = motor_power - 5;
ELSE
    motor_power = motor_power + 5;
WAIT 100 milliseconds;
If implemented, this code will get you from 0 to 100 power in 2 seconds. If you want to go from 0->100 in less time, increase 5 to anything you want. It is *highly* advised that you not decrease the wait time much, because if you go from 0->100 in 20ms, there's hardly any point to a revving system.

JohnFogarty 24-02-2010 17:52
Re: [FTC]: 4 Stage Gear Train HELP!
 
Quote:
Originally Posted by buddyb (Post 927978)
I agree with Abra. Our team uses 1:9, and it serves us really well. 1:36 seems like a bit much.

If you need to retain your current ratio, though, try code like this (pseudocode; will not compile in anything; you need to run this as a separate task, or integrate it in to your main loop such that it is executed without an explicit wait)
Code:
//5 for all of the values is arbitrary. For faster revving, go with 10 or so.
IF(abs(motor_power - desired_motor_power) < 5)
    motor_power = desired_motor_power;
ELSE IF(motor_power > desired_motor_power)
    motor_power = motor_power - 5;
ELSE
    motor_power = motor_power + 5;
WAIT 100 milliseconds;
If implemented, this code will get you from 0 to 100 power in 2 seconds. If you want to go from 0->100 in less time, increase 5 to anything you want. It is *highly* advised that you not decrease the wait time much, because if you go from 0->100 in 20ms, there's hardly any point to a revving system.
you'll have to really control it because if it's to strong you'll be disqualified.

FLHSFTC 28-02-2010 20:15
Re: [FTC]: 4 Stage Gear Train HELP!
 
1: 36 is actually too much, you don`t even need that much. 1: is pretty efficient because it can pretty much shoot over 5-6 feet, but less then 10 feet. I believe that if you should over that much, it would be considered a penalty. If you try to make the robot go for 1:9 ration on a shooter with only running 1 motor, it would not go as far as having two motors having the ration of 1:9. overall 1;36 is too much power 1:9 is just right.

HAL3019 06-03-2010 10:49
Re: [FTC]: 4 Stage Gear Train HELP!
 
Quote:
Originally Posted by FLHSFTC (Post 929843)
1: 36 is actually too much, you don`t even need that much. 1: is pretty efficient because it can pretty much shoot over 5-6 feet, but less then 10 feet. I believe that if you should over that much, it would be considered a penalty. If you try to make the robot go for 1:9 ration on a shooter with only running 1 motor, it would not go as far as having two motors having the ration of 1:9. overall 1;36 is too much power 1:9 is just right.
The way in which we are launching the balls calls for it, because we are trying to accelerate the ball using 2/3 of a wheel's rotation. Yeah... I know its a bit much, but we got it working around a week ago, we had to re-arrange the order of the gears in the train, plus we are working at maybe 50% power... so it should be 1:18 (we tried it, and it didn't have enough "weight" on the ball). Thank you all for your replies.

HAL


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