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Gearboxes for shooter?
oh-kay....
so we've been prototyping a shooter mechanism, using a CIM and the kit wheels from last year...only problem, we dont have any (easy) ways of powering it, toughboxes only give us around 300 RPM, so we took out a few gears and got it down to 4:1 wich should give us around 1200 RPM(hopefully) now ive heard(read) about other people just directly driving the wheel off the cim motor how can this be done? 1200 RPM should be enough right? if not we can use chain reduction(upduction:D) so the question is....what other ways are there to do this? (yes i read the other thread, this is more from a assembely standpoint though) |
Re: Gearboxes for shooter?
we're using a CIM on a 9:1 Banebots planetary. Gives us more torque so the wheel doesn't slow down as much as each ball goes through, and still keeps a hefty RPM on the wheel. Also theres the added benefit of really easy direct mounting since the output shaft is a simple 1/2" OD with a 1/8" keyway. Though we are actually going to use a sprocket combination with it to give the possibility of high torque or high RPM based on what our testing shows.
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Re: Gearboxes for shooter?
using a hub?
we have the 12:1 BB's but there kinda slow... |
Re: Gearboxes for shooter?
Well, the CIM is actually 4300 rpm
http://www2.usfirst.org/2005comp/Specs/CIM.pdf I'll assume it hasn't changed since 2005 |
Re: Gearboxes for shooter?
You can use a shaft on your wheel and a love joy shaft coupler to connect the two shafts.
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Re: Gearboxes for shooter?
You might consider using only a belt or chain drive, with a reduction ratio of about half the inch diameter of the wheel. ie. 4:1 for an 8" wheel. With the smaller pulley/sprocket on the motor.
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Re: Gearboxes for shooter?
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thats what we did, one CIM in a toughbox chained to a sprocket(which is bolted) on a 5/8 shaft. (using two kit wheels from last year, bolted together(not attached to the shaft at all!!! just the compressin of the wheel-bolts and the plastic hubs are enough to hold it on the shaft nicely) works pretty well, we are getting around 6ft maximum distance, and at 4ft were getting around 80% accuracy |
Re: Gearboxes for shooter?
A couple of years ago, for Aim High, we decided to just direct drive the wheels with a connector we designed to fit with the keyed shaft. It took some time to design the right parts but it worked well. It was a last minute addition and due to weight we didn't get to use it, but it worked really well. It's just another option.
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Re: Gearboxes for shooter?
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A direct drive from the 2.5" CIM is more than enough speed to get you more than your 6ft max distance with a 6" wheel. |
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Re: Gearboxes for shooter?
Be sure to read the other related thread
http://www.chiefdelphi.com/forums/sh...threadid=71854 Seems that it's possible to make it work with a direct drive CIM, or with chain/gear reduction. We're planning to build ours with chain reduction, that can be changed to see what works best. |
Re: Gearboxes for shooter?
Might want to check out Joe's "Nothing but Dewalts" White paper.
The combination of 3:1, 4:1 and 12:1 with servo shifting on the fly, plus the fact they are a fraction of the weight of the Banebots gearboxes make them a lovely addition to any FRC robot. We ran them last year on our drivetrain and were very impressed. You might even see 4 or 5 of them on our 2009 bot :rolleyes: |
Re: Gearboxes for shooter?
Some considerations that haven't been mentioned:
Good Luck! -John |
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Re: Gearboxes for shooter?
I think he could have cut and pasted from any year to get the experiment quote
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Re: Gearboxes for shooter?
well, the farther we shoot the ball, the less accuracy we have(unless we use the camera and everything) so we went for 4ft as our scoring distance, at less than 4ft it works just as well,
we're using two of these wheels bolted together(on the same shaft).... http://www.andymark.biz/08firstwheel.html not baseball sytle, just the two wheels bolted together on some 2x4's at 8inches tall and 8 inches wide we used the toughbox because thats all we had to get the wheel spinning fast enough(we dont have the parts for a direct drive off the cim) |
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Let's be honest... it has been a long time since I'VE put any serious thought into drivetrain turning. ;) -John |
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Patrick |
Re: Gearboxes for shooter?
Although it may be a bit overkill, you could always use FP motors in a DeWALT gearbox, and just limit the output in your code. We used these on our '06 shooter, and it worked perfectly.... although we didn't limit output alot... :rolleyes:
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Re: Gearboxes for shooter?
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We tried all kinds of configurations, different motor speeds, different backspins, etc. We came up with one big conclusion. Unlike the Aim High game when we dealt with just simple Poof balls, these orbit balls comparably are really difficult to deal with. Too much slipping and inconsistent distances, depending on where it makes contact with the orbit ball. Maximum distance and time that the shooter mechanism can be in contact with the ball prior to release from the robot, really improves the accuracy and grip on the ball. :cool: I'm not going to outright come out and say it, but there is "one" robot in '06 that I think we'll see a lot of this year, much like 121 last year. |
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