Prototype Small Wheeled Shooter
 

We just posted a blog entry about our current prototype shooter. It uses much smaller diameter wheels than many teams that we have seen post of CD. We're hoping this idea might inspire some teams that are struggling to package their large shooters.

Blog Entry with full specs on the shooter configuration.

Youtube Video

Re: Prototype Small Wheeled Shooter
 

Good shooter!! what motors do you have?

Re: Prototype Small Wheeled Shooter
 

The blog entry has the full specs for the prototype. The two motors are a BB550 and a BAG motor.

Re: Prototype Small Wheeled Shooter
 

Well...this is kinda awesome.

Re: Prototype Small Wheeled Shooter
 

You sir, have just lightened up alot of robots.

Re: Prototype Small Wheeled Shooter
 

Try slowing that second motor down (the BAG motor) . Try running it at ~10 volts.

See what happens. Easy enough to do.

Re: Prototype Small Wheeled Shooter
 

So you're actually spinning the 2nd wheel slower than the 1st. What made you decide to do that? Seems everyone is making the 2nd wheel spin faster than the 1st.

Re: Prototype Small Wheeled Shooter
 

Read the blog again. He is spinning the 2nd wheel FASTER than the 1st.

1st wheel 550 geared 10:1 = 1,930 free rpm

2nd wheel BAG geared 1:1 = 14,000 free rpm

Re: Prototype Small Wheeled Shooter
 

You are correct, I read the 14000 on the chart provided by FIRST as 1400.

I withdraw my question.

Re: Prototype Small Wheeled Shooter
 

Allen,

This is great work! I admire your lack of hesitation to give away this information. Shows you and your team's true colors.

Thanks and good luck at making it even better!

-Parker

P.S. - Have you tried shooting from the floor? What kind of angle do you expect to have to pitch the shooter to for the 3pter?

Re: Prototype Small Wheeled Shooter
 

Just wondering how you set the one gearbox to be a 1:1 ratio?

Also, anyone have any ideas as to how you mount the banebots wheels directly to a CIM?

Thanks

Re: Prototype Small Wheeled Shooter
 

On their blog they explained that they used a Versaplanetary box with all of the gears within removed. The output shaft of the VP boxes are the same hex as the banebots wheels.

Re: Prototype Small Wheeled Shooter
 

Thanks, didn't see that there.

Also we were wondering how you direct drive the banebots wheels with a CIM.

Re: Prototype Small Wheeled Shooter
 

The reason they are using the versa may be because the output shaft on a versa is actually a .5 hex, which is an ID that banebots sells their wheels with.

Locking a stage in a planetary gear is fairly simple - look up how people did it with globe motors. It involves glueing the sun gear and planetaries together with something, then dremeling off the teeth of the planetaries so they don't touch the ring gear.

FYI, you can't really be guaranteed that you can direct drive a banebots with a cim without installing an insert and broaching it with a keyway. The unfinished bores on the banebots wheels are not actually a measured diameter: it varies. They ream it to .375, but in most cases it comes bigger than the 8mm shaft of a cim from their manufacturer, and hence will not work directly on a cim.

Re: Prototype Small Wheeled Shooter
 

Re: Prototype Small Wheeled Shooter
 

We hope so.

Thanks for the recommendation; we still have a lot of work to do to optimize the whole setup. With the versplanetaries we can swap around motors and gear combinations so quickly that we plan to test a large number of them. We're also going to try to standardize on voltage as well, but that will take a bit more programming (since we don't have any type of speed feedback we can't do Bang Bang yet). We'll take your advice and test it. We agree that the last wheel is spinning too fast and is most likely slipping.


Thanks for the compliments. That really depends on how high we end up shooting from and our distance away from the goal. I'm not sure we could give a number. That height was less than 5 feet so in theory we could just shoot from there.

We took the ring gear, sun, and planets out of a 10:1 versaplanetary. I'm not sure if you can do the same with the other gearboxes. Paul Copioli can probably expand on that. If I remember I'll post pictures in tonight's blog update. We'll probably have to swap around a few of the gear ratios during testing anyway.

My thought would be to get an AM 8mm Hub and drill out the Banebots wheels for that and bolt them to it. I think it would work better than the 8mm to 1/2 hex adapter (It's not very long).

It's much easier than that. The spline on the output shaft is the same as the one on the sun gear. You just remove the whole 10:1 stage and bolt the front and back of the gearbox together.

Re: Prototype Small Wheeled Shooter
 

Will all three wheels fit on the versaPlanetary Gear Box output shaft?

Re: Prototype Small Wheeled Shooter
 

The three 0.4" wheels fit perfectly. The two .8" wheels have about .5" sticking over the top of the shaft, we just put a longer 1/4-20 bolt on with a washer, seems to work well enough.

Re: Prototype Small Wheeled Shooter
 

Why did you go with 2 different wheel thickness? Just what you had around?

Re: Prototype Small Wheeled Shooter
 

The .4" orange wheels can be bought using the BB PDV. We purchased 2 .8" of all three colors after we tested how grippy they were to the discs. We just left the .4" ones on there for now. We'll best testing a bunch of different wheel combinations over the next week.

Re: Prototype Small Wheeled Shooter
 

Great work guys. Can you tell us the distance away from the goal you were shooting into in the video?

Re: Prototype Small Wheeled Shooter
 

Wow. I'd never noticed that before.

Re: Prototype Small Wheeled Shooter
 

The front of the board was at about 15 ft.

Re: Prototype Small Wheeled Shooter
 

If you want to do speed control, your voltage at the desired shooting speed has to be a bit less than the lowest voltage you expect to see from your battery while you're shooting -- in order to allow headroom for you control algorithm to work.

Re: Prototype Small Wheeled Shooter
 

Did you or are you going to try the larger diameter (3.875" or 4.875") Banebot wheels?

Re: Prototype Small Wheeled Shooter
 

We didn't and we aren't planning too. We don't have any, and we like the small form factor. We did have a 4in RC Buggy wheel you can see in previous prototype videos on the blog that worked very well but it was too big for us.

Re: Prototype Small Wheeled Shooter
 

Better question is whether there's anything to be gained adding a third wheel to the setup so you can make a smother transition up to the final wheel speed. Something like starting with the BB550 in a 10:1 then BB550 in a 5:1, then the 1:1 BAG. I'm pretty sure the higher initial velocity your final wheel sees, the farther you'll shoot and faster you'll recover.

Re: Prototype Small Wheeled Shooter
 

1:1 BAG at free speed* is 14,000 rpm. With 2 7/8 dia wheel that's 120 mph tangential speed. With no slippage that's 60 mph.

If the frisbee is not exiting that second wheel at 60 mph it might be because it is slipping.

So, either:

1) crank down the speed of that second wheel a bit to stop the slipping and get a higher exit speed, or

2) crank up the speed of the first wheel, which is presently only 1930 rpm, which translates to 16 mph tangential velocity or 8 mph exit speed. A higher exit speed from the first wheel means a higher entry speed into the second wheel, which may reduce the slipping in the second wheel and give a higher exit speed

* I realize that due to windage and vibration it will be less than that

Re: Prototype Small Wheeled Shooter
 

Tonight's test has two BAG motors 3:1 and 1:1 (instead of a 550 and a BAG motor) and we're getting 30-35 feet from 2 feet off the ground and 0 degrees of incline. We also moved the blue wheels on the front and it seems slightly better. We're hoping that the harder wheels won't be eaten as fast as the green soft wheels.

Re: Prototype Small Wheeled Shooter
 

Nice. Can you gear that 2nd BAG speed down from 1:1 to 1.2:1 and try again ?

Re: Prototype Small Wheeled Shooter
 

Not easily using the VersaPlanetary they have, only 3:1, 4:1, 5:1 and 10:1 single ratios.

Re: Prototype Small Wheeled Shooter
 

Oh well. How about leave it at 1:1 and stick a Talon on there and use this to give it a 1.92 ms pulse width ?

Re: Prototype Small Wheeled Shooter
 

Your mounting of the banebots wheels would indicate that you have no issues with upside frisbees. Is this the case?

- Sunny G.

Re: Prototype Small Wheeled Shooter
 

We think it will shoot upside down discs once we put a cap over the wheels and opposite wall. We haven't tested that in a while but from our initial tests we know that the upside down discs ride up the wheels if the assembly is not covered. Once covered they should fly very nicely. The wheels are thick enough to contact the rim of an upside down disc.

Re: Prototype Small Wheeled Shooter
 

Ether, what exactly are you trying to get us to test? We were able to pull back about 80-75% on the joystick before we noticed any distance change. We still know the front wheel is slipping. We're pretty happy with the setup as it is, since we can meet all of our design goals and more. We won't be doing too many more changes to the shooter configuration. Once we get some other systems improved, we will be adding light sensors and white lines to the wheels so we can do bang-bang speed control and more precisely control our distance.

Re: Prototype Small Wheeled Shooter
 

Sorry, I thought you were still tweaking it, that's all. I didn't realize you already had it hooked up to a motor controller and were able to try reducing wheel speeds by changing the motor voltage and observing the effect on frisbee flight. If you mentioned that in an earlier post, I missed it.

Re: Prototype Small Wheeled Shooter
 

No we are still tweaking, we just use our previous robot and extension cables with Anderson Powerpoles. That way we have a quick way to get joystick control of motors. We unplug the drive train and use one side for each motor. Anderson quick connects make the prototyping go much faster. It's also safer so we have the protection of the breakers and we can disable from the driver station.

Latest shooter video is up on the blog. Not much changed expect it is now two BAG motors and the blue wheels are the only ones contacting the discs. We'll probably use all Blues since they seem to wear down less and we like the color a little better.

Re: Prototype Small Wheeled Shooter
 

Very cool!

Re: Prototype Small Wheeled Shooter
 

Here are photos of the different wheels as of today. Each of these wheels as seen well over 100 Discs each. The greens have seen the most and have also been damaged the most by the discs because they are so soft.

We are planning to use the blue wheels as we think they will last the longest.

Photo 1
Photo 2
Photo 3
Photo 4

We have heard of teams have trouble with Colson wheels removing some of the plastic from the discs. That has not happened so far with our shooter setup.

Re: Prototype Small Wheeled Shooter
 

Kudos for sharing such an innovative implementation. We've ordered parts to test this approach for use on our rookie robot. Any other photos, videos, or comments would be greatly appreciated. Thanks again.

Re: Prototype Small Wheeled Shooter
 

Glad we could help, I'll update this thread and/or the blog as we keep making improvements.

Re: Prototype Small Wheeled Shooter
 

Versaplanetary 1:1 Conversion Instructions

We uploaded the instructions for the 1:1 conversion today, hope it helps.

Re: Prototype Small Wheeled Shooter
 

All your information has been most helpful. Especially for a team with only one mentor and a very limited budget.

I know this got asked a few days ago.....
Does anyone know if the 1:1 conversion be done on the 4:1 and 5:1 versaplanetary units?

Re: Prototype Small Wheeled Shooter
 

I should have a 5:1 in my hand tomorrow afternoon and I can tell you.
You can probably find out sooner by PMing Paul Copioli.

The 4:1 and 3:1 come with an 8mm output shaft so it would be more useful if you could do the 5:1 which comes with the 1/2" Hex output.

The CAD models aren't really clear on how the input gear assemblies are made for each gearbox.

Re: Prototype Small Wheeled Shooter
 

You can make all of them 1:1. You can also order different output shafts and replace the 8mm shaft with the 1/2 hex or others....

Re: Prototype Small Wheeled Shooter
 

Eric is correct,

All of the different ratio gear boxes have the same spline (28T, 0.5Module Side Fit DIN Spline) coupler. The input housing, output housing, input coupler & bearings, and output bearings are identical for all gear boxes. The ring gear is also the exact same no matter what gear ratio you are using. The design is such that you can swap any ratio at any time and it just works. In addition, the direct coupler feature was designed in because we have always had issues on my team with trying to prototype using the smaller motors.

Allan's instructions are good and we also put the conversion instructions in our full user guide which should be out tomorrow. You just remove the ring gear, sun gear, carrier with planets and assemble the input housing directly to the output housing.

The shafts are also interchangeable so if you buy a 3:1 or 4:1 and want a 1/2" hex output shaft, just buy the hex output shaft separately and install it into the output housing.

Paul

Re: Prototype Small Wheeled Shooter
 

My intent was that if you buy the 5:1 or 10:1 you don't have to use snap ring pliers to change the shafts. A lot of teams don't have those and I don't know of a simple way to do it with out them. (If anyone does please let me know.)

Re: Prototype Small Wheeled Shooter
 

The Versaplanetary User Guide has been published by VEX, this should help a lot of teams that are trying to use them with their shooters.

Versaplanetary User Guide

Re: Prototype Small Wheeled Shooter
 

We got the 5:1 Versas and were able to convert one in about 3 minutes.

Re: Prototype Small Wheeled Shooter
 

Allen,

Thanks for all the good and open info on this prototype, it's great! We are emulating this design for another shooting prototype, and noticed that the 1:1 gearbox generates heat very quickly. Does your transmission do this as well? I suspect the bearings in the output shaft don't really like to spin at 15,000 rpm. (in fact, we actually released a little bit of magic smoke from a 550 just by spinning up the 1:1 transmission several times in quick succession)

If I had one gripe about the vexpro planetaries, it is that the motor is not indexed very well in the plate that it mounts too. This can lead to binding if teams aren't careful assembling it. That aside, I love these things!

Re: Prototype Small Wheeled Shooter
 

Glad to help,
That's one of the reasons we are using the BAG motors. I have heard they are better at dealing with heat than the Big CIMs. We've been running a 1:1 for a lot of tests over the last two weeks and they have been rock solid. A student even had a 1:1 BAG motor in a stall condition for about 30 secs (Frsibee caught in the shooter) and it didn't seem to do anything except get hot. The gearbox shaft felt hotter than the motor.

You do have to be careful mounting the motors, make sure you are following the directions on the VEXpro website. It's pretty simple to get a good fit since the motor shaft is doing the piloting.

Re: Prototype Small Wheeled Shooter
 

Thanks Team Spectrum!
We have one now
http://www.youtube.com/watch?v=zggvD...ature=youtu.be

Re: Prototype Small Wheeled Shooter
 

Sooo.... Is anyone else's small wheel shooter consistently pulling right? Or, atleast, pulling toward the wheels? Our is, and my working theory is it's because the wheels fall away and the wall doesn't. So the frisbee springs off the wall, which makes it pull towards the wheels. I'm thinking about replacing the end of the wall with something the same diameter as the wheel. Maybe even try bolting a wheel down on the other side. You'd probably lose some distance, but I think it'd straighten out your shooting.

Re: Prototype Small Wheeled Shooter
 

We just stop the wall at the center of the wheel seems to work all right, it does pull a little towards the wheel but the spin pulls it back the other way a little. It's consistent enough for us.

Re: Prototype Small Wheeled Shooter
 

Hello Allen

Are you using the 1:1 gearbox as a bearing system for the cantilevered shooter wheel shaft to take the side loads off the motor shaft?

Our team was able to demonstrate shootting frisbees at the upper goals yesterday evening. When I arrived this afternoon, they had the mini-CIM torn apart. Apparently the sleeve bearing at the end of the motor with the brushes had become severely worn and the rotor was dragging on the stator magnets. The shooter wheel was mounted directly on the min-CIM shaft.

Thanks.

Phil

Re: Prototype Small Wheeled Shooter
 

No we're aren't but we haven't had any problems with the Versaplantary gearboxes or bearings. If that becomes a problem we might have to modify our design to avoid cantilevered shafts but so far so good. These gearboxes seem to be be built very well as far as I can tell. Hopefully we can get through multiple competitions with out any problems.

Re: Prototype Small Wheeled Shooter
 

Do the VersaPlanetary gearboxes have a ball bearing at the input and output ends? If they do, all the side loads put on the shaft by the wheel would be taken by the ball bearings. The motor shaft would then only transmit torque and would not experience any side loads.

I think the shooter team were able to get about two dozen launches before burning out the rear bearing of their mini-CIM. One of them suggested buying a whole bunch of motors and swapping them when they burnt out. :eek: Neither the sponsoring teacher nor any of the mentors went for that idea.

Re: Prototype Small Wheeled Shooter
 

Yes, the planetary gearboxes do have bearings at both ends and we haven't had any issues with them.

Re: Prototype Small Wheeled Shooter
 

To be more precise, there are two ball bearings on the output shaft and one (I think, don't have one in front of me) on the input side holding the input coupling. So the output shaft can definitely support some cantilevered loads.

Do remember that you're not going to be able to stick a mini-cim into this gearbox. You'll have to go with a BAG motor and a 3:1 ratio, which will endup somewhat slower than your mini-cim. So you might be better off figuring out how to make up a shaft coupling and support system for the mini-cim.

EDIT:Actually, a BaneBots RS550 motor into a 3:1 gearbox gets you a similar free speed to the mini-CIM with a bit more power. You might try that combo as a drop-in replacement for your mini-CIM.

Re: Prototype Small Wheeled Shooter
 

Thanks for the info, Kevin and Allen.

I actually have a CIMULATOR left over from building the ball shooter last year. We also got a bunch of RS550's from Banebots using the coupon this year. We would just need to cut cooling chanels in the CIMULATOR so that magic smoke won't come out of the motors so easily. My rough calculations indicate that two RS550's would give a bit more speed (7148rpm vs. 6200rpm) and a lot more power (508W vs. 229W). We would just have to make sure that the motors are wired correctly so they don't fight each other.

Re: Prototype Small Wheeled Shooter
 

If you're clever, with a custom mount plate and a trimmed down shaft, you can mount a MiniCIM to a VersaPlanetary gearbox.

-John

Re: Prototype Small Wheeled Shooter
 

I'd love to hear more regarding details of your shooter: motors, gear boxes, gear ratios, wheels, voltage to motors, distance between wheels, etc. Thanks.

Re: Prototype Small Wheeled Shooter
 

I can't believe I didn't notice it was an 8mm hole until you said that.
I know what we're playing with next week. (Note: Not for our shooter)

Re: Prototype Small Wheeled Shooter
 

*blinks* So that's what that "notch" is in there for. Or so you'd hope. I wouldn't want to pin my hopes on that set screw in the CIM keyway.

Also, I have a feeling a mini-CIM would really push the limits on the load rating of the VersaPlanetary. And if you swapped a CIM in instead... Well that'd be extremely exciting.

Re: Prototype Small Wheeled Shooter
 

Depends entirely on the reduction, and output shaft configuration. Check out the loading tables at the end of this guide:
http://content.vexrobotics.com/vexpr...s_20130107.pdf

Re: Prototype Small Wheeled Shooter
 

I should have pictures up in the next hour or two. I have a student doing it right now.

Re: Prototype Small Wheeled Shooter
 

Instructions are up on our blog

http://3847.blogspot.com/2013/01/ver...-mounting.html

This was a pretty simple conversion. We cut the shaft more than would most likely be recommended but that lets you directly mount it to the Versplanetary with out any adapter plate.

Re: Prototype Small Wheeled Shooter
 

I don't recall but, do you have any video of shooting with the disc upside down?

Re: Prototype Small Wheeled Shooter
 

Not from this prototype, it needs some sort of cap over the wheels to get long shots with upside down discs (think the C channel from robot in 3 days), otherwise we find that the discs rise up out of the wheels before they leave the shooter.

Re: Prototype Small Wheeled Shooter
 

I stand corrected. If you're willing to green light a 1/2" hex shaft 300:1 BAG Motor for simple loading, that's the equivalent of a 1/2" hex shaft 50:1 big CIM motor. Which at 90 ft-lbs stall and nothing to sneeze at.

Allen,
Are the black spacers for standing off an AM-9015 motor too small to stand off the CIM?

Re: Prototype Small Wheeled Shooter
 

Didn't think about it but that does work. That will add back a 1/4in to the shaft.

Re: Prototype Small Wheeled Shooter
 

Hello guys, Nice job! We are experimenting with your setup and are having some degree of success. We have about 10 3/8 compression gap or 5/8 compression and we find the frisbee shoots straightest when the angle on the side ends with it being inline with the center of the last wheel. We do see that it goes straight , but if we make it a 1/4' longer it goes farther but not quite as straight. We also tried the gap between the two wheels at 1/4 " and with the centers 2" apart. It seems that the closer the wheels the farther it goes. We had the first wheel at 5K and the second wheel at 15k. Could you share your settings that worked best for you? Thanks. Again awesome job!

Re: Prototype Small Wheeled Shooter
 

We're nearly identical to that. BAG motors 1:1 and 1:3 wheels close together and the wall ending at the center of the fast wheel. Compression at about 1/2 inch. You have just verified our settings.

Re: Prototype Small Wheeled Shooter
 

I'd like to hear from teams -- if there are any -- who been successful spinning the 2nd wheel approx 30% to 40% faster than the second wheel, instead of 3x as fast.

Re: Prototype Small Wheeled Shooter
 

Do you have any reason to assume that is more optimal? We would like to know.

Re: Prototype Small Wheeled Shooter
 

It's a hunch, based on engineering intuition; there are too many hard-to-quantify variables to do any accurate calculations. Looking for some experimental corroboration or refutation.

Re: Prototype Small Wheeled Shooter
 

We're testing a 3-wheel variant tomorrow. Top speeds will be 4300, 6300, and 14000. That's 3:1 BAG, 3:1 FP, and 1:1 BAG. I know the FP is illegal, but it's equivalent to the BB 550 while I'm waiting for some 550s to arrive. I'm planning on trying it without the slowest wheel as well to see what differences we get. It's not your 30% slower, but it's a little closer.

Re: Prototype Small Wheeled Shooter
 

We are testing our linear shooter today.
We are using one CIM and one mini-CIM, each with a stacked pair PAIR of inline skate wheels - 76mm OD & 75A durometer.
These have dramatically better grip than all the other wheels we evaluated so far.
The disk are captured in the V formed between the two stacked wheels per motor as they spins through.

We have a piece of 80/20 20mm slotted framing opposite the wheels, and we cover the side with adhesive backed, high density urethane foam sheet material.
The friction factor is significant, as we found out with our 180 degree arc 8" wheel, direct mounted to CIM tests.
With the small wheel shooter, we are starting out with lower RPM (surface feet per minute) to avoid melting the softer urethane skate wheels, and we expect that the more optimized friction will make up for lower surface speeds of the smaller wheels.

As we confirm what our 1st stage alone can do, we will initially add the mini-CIM second stage for an extra 1000RPM. If that does not give sufficient exit velocity we will install the BAG 14K RPM motor as the 2nd stage.

We expect that much less compression (~1/4") will be needed with the more resilient and grippy materials contacting the disks. We also expect the groove in the slotted framing will help center the disk as it rolls along the length of the channel. If the slot in the frame is too narrow to keep the disk centered, we will machine a 3/4" radius convex curve into the side rail and it will then be covered with the dense urethane foam sheet.

With the V grip of the wheel pair on one side and the concave face of the rail along the other side, we will be able to keep the disk traveling through the shooter maintaining an air gap below the disk, and only the edge of disks touching the shooter as they accelerate through.

Hopefully nothing will be needed to hold the disk down from above either.

Video soon.

-Dick Ledford

.

Re: Prototype Small Wheeled Shooter
 

Would love to see the results of this, we are going to do three as well, but if there is no significant difference then we will want to save weight. Thanks!

Re: Prototype Small Wheeled Shooter
 

I'm working on getting some more quantitative results, but our preliminary results are, well, extremely promising.

Stats on our shooter prototype:
Baseplate is 1/4" lexan, unbraced. Shooter is a little bendy as a result. 2-7/8" orange wheels on 3.5" centers. Wall gap is 10.625". Theoretical top speeds are 4300, 6300, and 14000 at 12V. We're using the bright orange urethane flat belt as our sticky wall material.

For this particular testing setup, we're firing at a 19.5 deg angle, shooter was 41" off the ground and 25' from the goal. With three motors, we were nailing our cardboard just above the top of the 2 pt goal. With two motors it was landing about a 6" below the 2 pt goal.

This was testing an integrated solution with a 5 gallon bucket hopper right next to the firing wheels, so we were dragging the frisbee out from under some others. When we were hand feeding a frisbee in, it was throwing them over the top of our cheesy cardboard 2 pt goal and they were still rising. I'd say it would be about 18" above the 3 pt goal.

Re: Prototype Small Wheeled Shooter
 

Do you have Video? This info is great! We found that with a 10 3/8 gap it shoots farther, but we did not have non slip surface on angle. Will try adding that tomorrow. Here is our two wheel vid https://www.youtube.com/watch?featur...&v=Jc8g9WMoQ2o

Re: Prototype Small Wheeled Shooter
 

Would you mind sharing your shooting angle? We're currently set up at 45 degrees, but I'm starting to think that perhaps it's a little overkill.

- Sunny G.

Re: Prototype Small Wheeled Shooter
 

We haven't measured any angles yet, we just have the prototype that we just change the angles until we make it. On the actual shooter we will test and then measure the angle so we can put it in code.....If we get a chance today to test the proto then we will measure the angle.

Re: Prototype Small Wheeled Shooter
 

I want to give you and your team big props. We're using a similar design for our shooter and this has been a wonderful help!

Good luck at your regionals!

Re: Prototype Small Wheeled Shooter
 

We got our prototype shooter running Sat night and hit 5 out of 6 3 pointers in following configuration;

20 ft
Shooter at 25 deg
Two RS550s on 1:1 versaplanetaries
2 7/8" blue banebot wheels
10.5 in compression with top plate
Stationary rail was a painted 2x4
The discs were still rising as they passed through the goals.

Couple of interesting observations;
On our first setup the plates the gearboxes were mounted to would flex. Made quite an improvement to hard mount the gearboxes.
The top plate made a noticable increase in performance when we reduced the compression distance to 10.5"
Tried some 3 7/8" wheels and there didn't seem to be a noticeable difference in performance.

Re: Prototype Small Wheeled Shooter
 

http://www.youtube.com/watch?v=PuX7e...ature=youtu.be

Three wheels, 1/4" apart, 10/3/8" compression, no non slip angle
Ratios of gear boxes go 5 to 1, 4 to 1, 1 to 1 order of motors is Bag, am, bag

We are getting flexing in the base, will improve in final design

Tried non slip surface on angle not much difference, Orange flat rubber, wheel tread, tape ect....

The farthest we can shoot is 27 feet

Re: Prototype Small Wheeled Shooter
 

How is that 27 feet being measured. With just our two wheel shooter we were getting 30+ feet with the shooter mounted 2 feet off the ground and shooting parallel to the floor.

Re: Prototype Small Wheeled Shooter
 

Sure would be interesting to see a bird's eye view high-speed video in slo mo of the frisbee passing thru that third stage.

Re: Prototype Small Wheeled Shooter
 

will get that on Sunday

Re: Prototype Small Wheeled Shooter
 

Ok now we did 5, 3, 1 ratio

Shooting farther! Still have flex in base, will get more when we stop this
http://www.youtube.com/watch?v=wGp3M...ature=youtu.be

Re: Prototype Small Wheeled Shooter
 

Very nicely done.

Re: Prototype Small Wheeled Shooter
 

Think its due to our base flexing, it will not in the final model. We did shoot from around the Pyramid so it may be 30, 27 was in straight line

Got slow mo of two wheel
http://www.youtube.com/watch?v=cq3feDdl6A0

Re: Prototype Small Wheeled Shooter
 

That tells me you had a lot of slipping in the 3rd stage. Maybe you still do. Try 2:1 for that second stage.

Re: Prototype Small Wheeled Shooter
 

Just measured the latest distance in the hallway, from video last posted of three wheel shooter. 48feet! from 2 1/2 feet above floor

Re: Prototype Small Wheeled Shooter
 

isn't it illegal to trim the shaft of the motor down?
Well not illegal in Texas perhaps but illegal in FIRST?

R

Re: Prototype Small Wheeled Shooter
 

4.1.7.2 R33-A

Re: Prototype Small Wheeled Shooter
 

R33 give us permission to modify the output shaft otherwise tightening a set screw too hard would be illegal.

Re: Prototype Small Wheeled Shooter
 

Thanks to Allen & Ether for posting the relevant rule. It is allowable per FRC Ultimate Ascent rules to modify a CIM shaft in this way.

I have contacted the Texas state legislature regarding your question, but have not heard back yet. My buddy is a cop, and he says he's never had to arrest anyone for it, and thinks that if there is a law against it, it is probably one of those ones which isn't strictly enforced. I think we can assume it is okay until we hear otherwise back from the TX lawmakers.

Luckily, Gov Rick Perry is a fan of robotics and FRC -- if there is a problem in TX maybe he can help us resolve it?

-John

Re: Prototype Small Wheeled Shooter
 

No we just turn robotics into an underground sport down here. Think of the wonderful and terrifying implications.

Re: Prototype Small Wheeled Shooter
 

There is a special place in the afterlife down under (hint: not Australia) for people that crank down set screws into keyways.