ball dumpers/throwers types
 

Our team is discussing the nature of the ball dumping/throwing mechanism and I thought I'd ask you Chief Dephi-ers what you think. The opinions fall into 2 basic camps: 1) dump multiple balls at once using a gravity-feed wide front dumper that allows multiple (2-4) balls to fall out at the same time 2) dump balls serially using a mechanism that forces the balls out quickly (think very slow softball pitcher) and can rotate 180+.

Note that the desired dump rate is "as quick as possible" in both modes.

I think a wide dumper is problematic. You are trying to align a rectangle (the robot) with a circle (the trailer). The point of contact is not an edge but a single tangent point. Any balls dumped left and right of the center of the trailers center point have a smaller chance of getting in the trailer. Plus the surface not only means trouble de/accelerating but also positioning the robot. So I think a directional dumper is important.

Thoughts, discussions, comments?

Re: ball dumpers/throwers types
 

We're working on a single ball at a time design. One problem you run into with more than one ball wide, is that they like to get stuck.

Re: ball dumpers/throwers types
 

While we are still designing the design that I am working on protos for has a wide front, yet conveyer belts on top and bottom allowing it to be powered and multiple balls at once.

Re: ball dumpers/throwers types
 

Since your dumper is confined to quarters snug as a bug in a rug within the very safe confines of your robot's bumper perimeter, consider, all ye gravity fed dumpers, the minimum horizontal distance the balls must travel to find their way into the trailer promised land - the width of your robot bumper, the width of the trailer bumper, and whatever distance lies between the trailer base's edge and its vertical poles. Perhaps a chasm too great to traverse without additional aid....or perhaps not, with certain frame modifications. Either way, something to keep in mind as you design.

Re: ball dumpers/throwers types
 

That's not necessarily true

Re: ball dumpers/throwers types
 

We finished building our trailer today... if you hit that big centre post with a fairly flat or downwards trajectory and a bit of backspin... it looks like you should score every time.

We've had success shooting the balls 6 to 10 feet just by spinning up an old 8" wheel on a lathe and either dropping the orbit ball on it, or compressing the ball between the wheel and a sheet of plywood.

So I'm thinking one ball at a time, but reasonably rapid fire, similar to 2006.

Jason

Re: ball dumpers/throwers types
 

We did about the same thing, but we really just took the big CIM off of our 2006 robot (of course, we won't be using the big CIM...). A problem that I'm seeing right now just because of how the polycarbonate we're using guide the ball down, and with the shaking of the motor being mounted by 1/16" aluminum or something along that lines (might be thinner), the feeding will have to be centered, otherwise the motor may slow down a little bit. We've even had it jam before.

Re: ball dumpers/throwers types
 

why not just build two harvesters and run one in reverse?(HINT HINT)

Re: ball dumpers/throwers types
 

Thanks, Jason, as usual you prototyped our design for us, and found a way to make it work :)

Re: ball dumpers/throwers types
 

How much does your completed trailer weigh?

Re: ball dumpers/throwers types
 

One of the ideas that we were considering was an active dumping system which is to say instead of relying on gravity to do our dumping we will have a a dumper which can propel the balls into opposing trailers. Also we will be able to control the dump in case the opponent manages to move out of the way. The design includes two barrels which should increase the rate of fire. It's an early desgin concept that still needs fine tuning but we fell we could take it somewhere.

Re: ball dumpers/throwers types
 

Man, we have a lathe and everything... our students took alot of time to build a roller setup out of 80/20 scraps and a 2008 KOP wheel. The lathe idea is a great idea so we can figure out what rpms to set the spindle motor to!

Our design isn't simply a wheel though, it will be a roller that's 4" wide (or a 1-2" diameter wheel that's 4" wide, however you look at it). I'm also toying with the concept of making it a sort of conveyor design so that the moonrock has more acceleration time. Thoughts?

Re: ball dumpers/throwers types
 

This hasn't been my experience. In fact, I've found it to be quite the other way around.

It's much easier to shoot downwards on either side of the big pole and make the shots. If you aim for the pole they just bounce off...

As for static mechanisms, like dumping.... Its just always been my experience that if you don't force the game pieces to do what you want they usually won't do it :D

Re: ball dumpers/throwers types
 

Dumping multiple balls at once isn't practical. feed the balls one or two at a time would be better, but then the dumper jams easier

Re: ball dumpers/throwers types
 

Can anyone post a video of the shooting so that i can show my team?

Thank you.