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This part hadn't yet been designed when I posted pictures of the CAD models of our machine. It's since been added and manufactured, obviously.
The side plates have been the single most complicated piece we've milled to date, though they weren't difficult to do so much as time consuming. They each weigh .1 lbs.
The wheels are driven by, currently, a single large CIM at 1:1 gearing. The motor has had its timing pulley removed and the shaft fitted into a larger 1/2" shaft with a set screw put into the CIMs flat to keep it all snug and spinning together. The sprocket is bolted sideways onto the larger diameter part of the shaft. The opposite of the shaft is similarly built to accept a second large CIM motor if it's needed.
We're a little skittish about using chain running at 2700 RPM, but we'll give it a try and see what happens. We can easily switch to belting if chain doesn't work out.
Discussion
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03-02-2006 19:29
Nitroxextreme
Re: pic: FRC488 -- Ball Shooter
Just to give you a heads up on the chain running that fast..it works
Our team is using the big cim motor and gearing it up 
...the chain stays on the sprockets with ease and we have yet to have any major problems besides small wobble
03-02-2006 22:27
Heretic121
Re: pic: FRC488 -- Ball Shooter
what type of recoil time are you getting *time needing to wait between getting identical distance on shots...
03-02-2006 22:34
Madison
Re: pic: FRC488 -- Ball Shooter
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Originally Posted by Heretic121
what type of recoil time are you getting *time needing to wait between getting identical distance on shots...
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Our shooter was prototyped by another mentor and some students using the small CIM, not the large. We collected some data based on that to get a better idea of the load it was seeing and things like that -- and then I applied the data to my calculations for the final design.I think we'll have good success with shooting while running the motor at just 9V average or so based on my calculations and design which'll give us a bit better recovery time than something with similar shooting performance at 12V. Time will tell, though. The final track around which the balls will travel hasn't yet been fabricated, so we haven't tested this final implementation.
Interestingly, our prototype shooter shot the second ball in a series farther than it did the first. The backing about which the balls rolled flexed as the first ball exited, causing the trajectory of the second ball to change. It is neat and, while not something we intend to replicate, would be an interesting technique to apply to counteract energy losses.
03-02-2006 23:12
Donut
Re: pic: FRC488 -- Ball Shooter
I don't know about chains, but we know belts work that first (we're using it for direct drive between big CIM motor and a 9" wheel).
I don't know how it will be for this, but through our testing we've discovered we can shoot balls at ~1/2 second intervals and get the same distance. This was with a shooter that didn't have the surface the ball is pushed against completely secured though, so it may be faster once it's completely put together.
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