Frisbee shooter
 

Hi everybody! Our team and i, are trying to build a new shooter, we tried with some youtube videos, but the frisbee doesnt have speed! How can we make a new shooter quickly? Our offseason event is on october 26th!
HELP!

Re: Frisbee shooter
 

What kind of shooter (Linear/half circular) do you currently have, and what type were you trying to emulate?

We are trying with the half circular, and from last season it was linear but it was not good enough. Maybe tomorrow i can post a photo of the two of them

Re: Frisbee shooter
 

Pretty much everyone with a semi-circular shooter either emulated, or ended up with something similar to 973's design. Ours was a 60 degree arc (arc radius = diameter of frisbee + radius of shooter wheel) minus a small amount to add some compression to the frisbee.

This image shows their shooter pretty well.

http://www.greybots.com/uploads/1/4/...0_orig.jpg?292

This was shown to be one of the most effective designs by the time the season had ended. I would highly recommend starting with that and changing as necessary.

So is it good to add some compression to the frisbee??
We'll try with that formula and i'll show you our shooters.
Thanks

Re: Frisbee shooter
 

For compression, my team used rough top & some squishy tape stuff.
More friction = high flying frisbees.

Re: Frisbee shooter
 

Probably most important is what resources do you have to build your shooter in 10 days with? If you could post a picture of your previous linear shooter and current shooter that would be great! What wheels do you have or have tried in the past? What gearboxes do you have sitting around your shop?

Our linear shooter was three bag motors through 1:1 versa planetaries with 2 7/8in banebots wheels. Opposite our shooter was a wall covered in wedgetop tread and compressed the discs about 1/2in. We noticed a huge difference in our shoot distance/consistency when we added more compression.

Re: Frisbee shooter
 

You need compression on the frisbee to transfer enough kinetic energy to it. Some of the 3M grip tape or other friction material will be useful on the wall. For the wheel, the BaneBot, pneumatic, and AndyMark hi-traction kit of part wheels worked well.

You can make a very effective shooter out of plywood. The hard part is indexing your discs so that you don't jam the shooter.

Re: Frisbee shooter
 

The purpose of compression is mostly to reduce slipping between the frisbee and the wheel, and the frisbee and the fence, to impart spin. Without spin, the frisbee will not travel very far. That's why most teams add some sort of friction surface to the fence. You want the frisbee to roll on the fence, not slide.

Re: Frisbee shooter
 

Here's what our team's shooter looked like:
http://i.imgur.com/cTw6mas.jpg?1
http://i.imgur.com/KRfkpUV.jpg?1
We used two mini cims and I believe we geared them down slightly. The blue thing is a piece of foam similar to pool noodle material (I think what we actually bought was a yoga mat). This material gave us compression and and the wedgetop tread on our shooter wheel provided grip. Together these allowed for minimal slipping on the frisbee. We cut an angle into the foam to prevent the frisbee from walking up the side of the channel and we added teflon tape to the plexiglass rails that the frisbee rested on in order to reduce friction as much as possible.

Re: Frisbee shooter
 

We used a linear design that got plenty of speed. We used two pneumatic wheels attached to a CIM and Mini CIM, with distance from the edges of the wheels to the other side of the track 1/2 an inch smaller than the frisbee diameter. (We cracked a piece of plywood with our shooter around 80% power).

http://www.youtube.com/watch?v=AfY-uYwHv50

Re: Frisbee shooter
 

Hi, here are some fotos of our shooter.
We have a mini CIM and a CIM connected directly to two wheels of 6" diameter; the shooter is linear so we have a space between the wall of acrylic and the wheels of about 27 cm. We try to shoot at 30 degrees then in 45, but we stell have problems geting the height (we only get like 1,70m ).
I don´t know were is the problem, maybe it could be the compression of the frisbee or the speed of the wheels (we connect both motors to the battery and I think we achieved good speed)

any help will be great

Re: Frisbee shooter
 

I have not seen many teams have much success with those wheels as shooting wheels. If you click on the link in my signature you can see how well they worked for us (not saying they can't but there certainly are better options). I would recommend these pneumatic wheels but it looks like you have a different concept in mind. So instead, I suggest using these wheels and play around with different compression and opposite wall surfaces (the goal as Ether pointed out is to get the disk to rotate).

Re: Frisbee shooter
 

If you can get the packaging to work, CIMs direct-driving the 8" pneumatic wheels in a linear or circular shooter with some compression work great.

Re: Frisbee shooter
 

If the poly carbonate you are using for the shooter is flexible it may be wasting all of the compression you have tried to make.

Re: Frisbee shooter
 

our offseason is this saturday, maybe we could ask for pneumatic wheels to a team close to us.
we are going to try changing the fence from acrylic to wood

Re: Frisbee shooter
 

We had marginal success with a radiused shooter using similar speeds in the spring, but decided to attempt to recreate team 67's incredible shooter as an offseason development exercise for our new builders. The results were incredible. While it is obviously not the only way to do the job...it works.

Whatever you end up with - don't overlook compression of the discs...that was the biggest factor affecting the performance of our radiused shooter - but it was very difficult to adjust the compression in that configuration...in a linear shooter it's just a matter of moving the fence.

https://vimeo.com/75662715

Re: Frisbee shooter
 

I don't know what your team's situation is at the moment, but given your 2013 record (I checked The Blue Alliance) and the way you phrased your question, your team is in no to be creating a shooter.

I regret that I didn't discover this thread until today, else I would have tried to dissuade you a week earlier and saved you a week of wasted time. The other respondents to this thread have given excellent advice on creating a solid shooter, but that advice is the result of thousands of hours of cumulative experience and practice. Obviously, each individual shooter will be unique, and will need its own tuning. Your team does not have the time or experience to be able to make a consistent shooter by Saturday; the fact that you are posting today to say that you don't have a functional shooter yet only confirms my suspicions.

Your team should abandon all work on the shooter and focus on what is actually important for your robot: drivetrain and driver practice. It has been said for years, for very good reason, that a good driver on a terrible robot will consistently outperform a poor driver on a world-class robot. If you focus on training your driver, on a properly working drivetrain, for the next few days, your team has a chance of making a positive impact on your elimination alliance. If, on the other hand, you continue to work on your shooter, you will fail at both shooting and driving.

Of course, it's possible that your team cares more about creating a shooter as an engineering exercise than for competitive reasons. Even so, I, as a student in my third year of FRC, personally believe that engineering a good drivetrain is easily the most important part of creating a robot, and is by no means simple or easy.

I'm sorry if I punctured your bubble of happiness. If I could have done it sooner, I would have. In all honesty, I'm surprised no one else brought this up sooner.

Re: Frisbee shooter
 

Team 1986 shooter: 2 stage
1st stage - CIM direct drive, 2008 KOP wheel (6" w/ solid rubber tread), 50 degree arc of contact against bare solid wooden fence, 1/8" of compression.
2nd Stage - Mini-CIM direct drive, 2008 KOP wheel, straight path against bare aluminum fence, 1/8" of compression. Approx. 6" of close 3-sided guiding after the final wheel.

Re: Frisbee shooter
 

In our first iteration of our shooter we had a bare polycarbonate side wall supported by aluminum. Our initial results were less than satisfactory (only a few meters). We added a tacky material to the side wall and the results were astounding. We were shooting a few meters before and with the added sidewall material we could shoot full court.

Re: Frisbee shooter
 

As a counterargument, our two wheeled linear shooter had plenty of shot consistency with a smooth polycarbonate wall on the opposite side. Our shooter was far from an optimized solution, but if you're trying to build a simple cycler, you don't need a perfectly optimized solution. You just need a consistent and effective solution.

Here's our shooter specs, if it helps you:
- Two Banebots 4 7/8" wheels plugged into two mini cims or a cim + mini-cim (honestly doesn't matter) using the AndyMark 8mm to hex adapters
- 10.5" between the tips of the wheels and the opposite wall of the shooter (so .5" disc compression)
- Polycarbonate on the opposite side of the shooter. I've heard from MANY teams that wedgetop tread or other grippy material works well, so consider that an option too, but you might not need it.
- Plastic strips above and / or below the shooter barrel such that frisbees sliding through are physically constrained in the shooter. Basically what this does is it forces the frisbee to contact both wheels rather than lifting up between the wheels and not getting full contact. This dramatically improves vertical consistency.

We used an aimable shooter so I can't tell you if this consistently fires the exact same height over 1,000 shots, but if everything was working all 4 discs would hit almost the exact same place every cycle. This definitely isn't the best way to build a shooter, but "done" is better than "perfect".

Re: Frisbee shooter
 

Perhaps your larger-than-normal compression mitigated to some extent the sliding due to the polycarb fence.

Re: Frisbee shooter
 

That's possible, certainly. I was under the impression that .5 inch compression is standard for linear shooters. 1/4-1/2 turn shooters use less.

Looking at markings left on the frisbee by the wheel, the length corresponds to the contact patch of the frisbee on the wheel if it was being "rolled" through the shooter. A slippery system would have a shorter contact patch as pressure would be applied to the same spot for longer.

Re: Frisbee shooter
 

Our linear shooter also had .5in of compression. Three 1:1 Bag motors with 2 7/8in banebots wheels and wedgetop tread on the opposite side.

Re: Frisbee shooter
 

We evaluated multiple designs early, and ended up with a single wheel, 8" pneumatic, lineral shooter design. Our strategy was to shoot from back of pyramid, unblockable to the 3 point. We were a tall bot, and when we were too tall to be agile, we morphed into a full court shooter. We never had a reason to redesign the shooter to shoot 2's, shooting 3's we needed a little more power to get our accuracy above 80% shooting 3's.

We had very accurate and active speed control on the wheel, are you missing that?

http://www.mcbride4.org/?attachment_id=82

https://www.facebook.com/photo.php?v...type=3&theater

Re: Frisbee shooter
 

My team used a linear design, but the properties are the same for both linear and circular designs. The key is to have as much grip/friction on the wheel and the other plate the frisbee is riding on. With these two points of contact, the frisbee will get a good spin=longer distance and higher rise. Another main thing that you will want to focus on is the compression. The compression determines the friction between the two points of contact on the frisbee. My team never got our compression perfect, but after some trial and error, you will get it right. One last key is to have the frisbee travel through the shooter will little to no friction, this is to keep the spin and speed constant throughout the shot for an accurate ending location (use a material like delrin).

Re: Frisbee shooter
 

Finally we shoot as we wanted, we use the mini CIM and the CIM, and the wheels 6" diameter. we change the wall with wood.
We try to power the wheels at different speeds, the first motor (mini CIM) has a regulate speed and then the CIM the maximum speed.
We almost reach 110" hight at 6 mts distance.

Re: Frisbee shooter
 

How are you going to feed the shooter?

(Hawaiian Kidsth post!)

Re: Frisbee shooter
 

Very similar to our shooter however our CIMs are switched, with the full CIM first then the mini-CIM. The mini RPM is 20% higher the the CIM, so it naturally runs faster with both running full speed. Works wondefully for us.

Re: Frisbee shooter
 

This! flip the motors and run both on full, you might need to turn the speed down a bit if there's too much slippage the wheels will just do burnouts on the disk.

The wood probably added some much needed support. Shooter really need to be rigid, or the force will transfer to the robot instead of the frisbee.

In our 90 degree shooter(different beast), we found that using double sided tape with different thickness sheet metal/polycarb/traction material was an excellent way to tweak the compression/friction to see what gives the best the distance/accuracy.

Re: Frisbee shooter
 

How do you know they don't have a practice robot they are working with already? Maybe it was mentioned they don't and I missed it, or you just know they don't. I agree that it is sometimes wise to abandon part of the project to save the baby. Worth asking before you burst bubbles IMO.

Re: Frisbee shooter
 

We are glad to tell everybody who help us. that our shooter is ready!

Re: Frisbee shooter
 

The pictures they posted after the comment you reference was made do show what appears to be a very capable drive system with mecanum wheels. I agree: take the request at face value and don't assume.

Good luck on Saturday 3794.