Hopper Design
 

After last weeks TCNJ FRC District Competition. a few other team member and I had a though about changing our hopper design and adding a new human player feeder. and we came up with a design of a square hopper because it would have less areas of contact with a frisbee than a circle but still does its job of holding the frisbees in. It also solves many other problems we have been having with a circle hopper. How do you guys think about this? :confused:

Re: Hopper Design
 

Just go to Home Depot/Lowe's and buy a bucket like everyone else is. It's a solid solution that is cheap and easy. Also if you cut it wrong it just costs $5 to get a new one.

Re: Hopper Design
 

What problems have you had with the circular hopper?

Re: Hopper Design
 

We switched from a square hopper to a circular hopper after running into a lot of issues with frisbees not stacking particularly well in the square hopper and jamming the feeder. Square wasn't the way to go for us. I think the more sides you have keeping it centered the better, and a circle has infinite sides.
Drawbacks: the circular hopper is tempermental to any pinching, so you have to be careful to keep it round with any attachments or fastening.

Re: Hopper Design
 

Get a five gallon bucket from Lowe's/Home Depot. (I recommend getting several...so you don't hesitate to experiment/screw up...they cost us less than $3 each.) The buckets are great because they taper only slightly, almost imperceptably from the top to the bottom. Put a disc into the top....and it stops about 6 inches from the top. Draw a circle around the bucket where the disc stopped. Slice the bucket at this line or just above it, to establish the bottom edge of the hopper. (We used a Dremel with a metal disc cutter or sharp box cutter to cut the bucket.)

The slight taper in the bucket is nearly the perfect shape to keep the discs stacked, yet not nested so much that they do not separate or jam, and not so tight that they jam in the cylinder as they drop.

From there, experiment with an exit slot in the bottom (needs to be 1.4 inches high), a means to transition from the hopper to the chamber/shooter barrel (we use a pneumatic piston, without any clevis attached), and a means to feed it. For feeding, we cut about 225 degrees around the uphill and top edge of the bucket, cutting down about 1" from the top. With the sloped cover to the shooter, we have a good backstop for discs to hit, and drop into the hopper.

Dozens of examples are shown in the reveal videos. Your own geometry will vary, depending on you shooter configuration and space available on the robot.

We have been using a circular hopper made out of a 6 gallon bucket we found. We went through our district competition with one. And it had issues of the frisbee getting stuck and not falling in straight. So I was wondering if a square would be better.

Re: Hopper Design
 

Use a 5 gallon bucket from home depot / ace.

We prototyped square and it was a mess. Two days later we were back at a bucket. Rember that you can't use the whole bucket, only the top 6 or 7 inches is wide enough to pass a frisbee without binding.

Re: Hopper Design
 

4343 and 1114 went the 'dont stack the frisbees' route, which seems to be less jam-prone, provided you only index a single frisbee at a time into the pre-launch position of the shooter.

4343's design made human loading quick, and prevented the frisbees from jamming up their hopper by falling in sideways as is possible on many robots I've seen.

Alright. thanks for the advice guys :)

Re: Hopper Design
 

They only fell out the top :rolleyes:

Re: Hopper Design
 

Well, yeah. The indexer motor needed to be about 3" further down the hopper, and that problem would have been entirely alleviated.

Re: Hopper Design
 

we have a custom made sort of square shaped hopper, with "stairs" that we built out of polycarb. here's a video where u can see how it works and stacks Frisbees... altho i'm not sure i'm supposed to be sharing it :P

http://www.youtube.com/watch?feature...&v=f_v3UbFI_6U

Re: Hopper Design
 

We had a square hopper, but in order for things to work perfectly, it became very complicated. It also became very finicky, working one day and not the next. We're currently switching to a round hopper.
Good luck with what your trying!

Re: Hopper Design
 

We've been using a square hopper and it's been working pretty well for us--we tried the bucket method briefly, but decided it wasn't really worth it for what we were trying to do. However, we do collect and shoot from the bottom (we built it for floor collection, but after Lone Star we decided that it might be better to human feed through the bottom slot, and it's working quite well for us) and it's powered, which helps make collection quick and reliable.

What are your dimensions for ur hopper?

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