Re: Hopper Design
 

Sudden thread revival time!

I'm designing a new robot for our team's offseason events and have been interested in the square hopper design. I know 11 used it with success and a number of my friends prototyped it and it worked well for them as well. In the 2013 season we used a bucket and, while it "worked", it bent a lot and got pretty beaten up. I believe a strong, aluminum square hopper would pose little problems, though this thread has lots of people saying their square buckets didn't work.

Now that the season is over, what is your opinion on square buckets? Has anyone who tried them had problems? If so, please describe the problems, and indicate whether the problems could have been attributed to another part of your robot rather than your square hopper, since that is a factor.

Re: Hopper Design
 

we used a square hopper this year and it worked out great once we figured out how to que discs in it. what we did was have the back wall that the frisbees fell into and hit be slanted and also have a small shelf that hung over the first frisbee and caught subsequent discs. the geometry made it so that only one disc could get in and virtually never jammed.

it ended up looking something like this from the side
_....\
-___\

theres some good close ups of it in this video
http://www.youtube.com/watch?v=CdioctP9Bck&t=1m40s

Re: Hopper Design
 

I hereby disclaim that I have no experience with hoppers at all.

If you're open to other, non-hopper solutions to holding disks, though, you may want to look at teams like us or 973, who stored disks in a line, not stacked on top of each other.

I can testify that our robot's tray of disks worked well. There was only one match where we had trouble, and that was due to a piece of the orange polyurethane belt's black electrical tape being ripped after two regionals and half a championship, with no maintenance. 973 was at Archimedes (we allied with them for eliminations) and both won LAR and were finalists at SVR.

You can see our robot's videos on our Youtube channel, if you're interested; I don't know of any of 973's videos.

Re: Hopper Design
 

We are using a circular hopper and it worked great. However, we got one jam after champs and it got a little warped, so now it doesn't feed right(as in, they stack 75% of the time instead of 95%). It's not even a visible difference. I guess I would suggest making the hopper slightly larger than needed (extra 1/4 inch dia. maybe) to compensate. Once it goes through the shooter, one as violent as my team's, anyway(look up video of us at midwest), that space isn't going to affect the trajectory of the frisbee, anyway.

Re: Hopper Design
 

And we won one ;)

Re: Hopper Design
 

Thanks, original post now edited accordingly.

Re: Hopper Design
 

we used a big metal pot. it looked nicer than an orange bucket, and there was no problem with pinching. also we could weld it to the rest of the shooter assembly

Re: Hopper Design
 

I know you were asking about square hoppers, but if you have the resources you can make a very durable circular hopper.

This year our team used a PlasmaCAM to cut out a piece of sheet metal to the exact size, so that when rolled the frisbees would fit with minimal movement. We then just welded it together, and cut out some rings from sheet metal to weld to the outside to help keep its shape. The rings on the outside also made it a lot easier to attach our hopper to the frame.

If you need I can try to find some close up pictures of it.

Re: Hopper Design
 

In our experience, we used a cut-down upside down 5 gallon bucket, and a toggle bolt connected to a guided air cylinder to pull the bottom disk from the stack, directly into the shooter wheel. Our main feeding issue was that the second disk would nest perfectly over the bottom one, making it tough to pull the bottom one out, causing jams. The fix proved to be a set of wedges, about 3/8" thick and spaced around the inside bottom of the bucket, on the back side, to push the bottom disk forward, toward the shooter wheel. Consistency ensued, and the villagers rejoiced.

Re: Hopper Design
 

Very Clever use of a toggle bolt here. I saw many teams custom fabricate something equivalent, when the toggle bolt would have been fine.

Re: Hopper Design
 

I'm not familiar with toggle bolts... Is it some kind of linearly actuating sliding pin?

Re: Hopper Design
 

They're a fastener used for hanging items in drywall walls. They have a sprung loaded anchor that allows it to be shoved through a hole in the wall, then expand.


From google

Re: Hopper Design
 

Thanks, Adam.

For those unfamiliar, the toggle bolt is spring loaded in one direction, so it pulled the frisbee out from the hopper, and sprung out of the way as the frisbee passed over. It helped make the packaging a little easier and kept our feeder well protected from aggressive play. We also riveted a small piece of lexan to the "active" toggle bolt wing to limit any frisbee damage.

http://www.google.com/imgres?imgurl=...EwBg&dur=13104