Prototype Small Wheeled Shooter

[AllenGregoryIV]

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 (http://3847.blogspot.com/2013/01/day-11-ultimate-ascent-shooter-testing.html) with full specs on the shooter configuration.

Youtube Video (http://www.youtube.com/watch?v=oTFTWgB1cY4)

[frcchile]

Good shooter!! what motors do you have?

[AllenGregoryIV]

Good shooter!! what motors do you have?

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

[James1902]

Well...this is kinda awesome.

[dodar]

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 (http://3847.blogspot.com/2013/01/day-11-ultimate-ascent-shooter-testing.html) with full specs on the shooter configuration.

Youtube Video (http://www.youtube.com/watch?v=oTFTWgB1cY4)

You sir, have just lightened up alot of robots.

[Ether]

Blog Entry (http://3847.blogspot.com/2013/01/day-11-ultimate-ascent-shooter-testing.html) with full specs on the shooter configuration.

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

See what happens. Easy enough to do.

[EricLeifermann]

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.

[Ether]

So you're actually spinning the 2nd wheel slower than the 1st.

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

[EricLeifermann]

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





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

I withdraw my question.

[ParkerF]

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?

[Robo Hamsters]

We just posted a blog entry about our current prototype 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

[Botwoon]

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

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.

[Robo Hamsters]

Thanks, didn't see that there.

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

[Tom Line]

Thanks, didn't see that there.

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

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.

[IndySam]

Thanks, didn't see that there.

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

8mm 500 Hex Adapter Shaft (am-0588)
(http://www.andymark.com/product-p/am-0588.htm)

[AllenGregoryIV]

You sir, have just lightened up alot of robots.

We hope so.

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

See what happens. Easy enough to do.




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.

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?


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.

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

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.


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

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).


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.


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.

[falconmaster]

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 (http://3847.blogspot.com/2013/01/day-11-ultimate-ascent-shooter-testing.html) with full specs on the shooter configuration.

Youtube Video (http://www.youtube.com/watch?v=oTFTWgB1cY4)

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

[AllenGregoryIV]

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

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.

[EricLeifermann]

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.

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

[AllenGregoryIV]

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

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.

[JB987]

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.

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

[Tom Line]

8mm 500 Hex Adapter Shaft (am-0588)
(http://www.andymark.com/product-p/am-0588.htm)

Wow. I'd never noticed that before.

[AllenGregoryIV]

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

The front of the board was at about 15 ft.

[Ether]

We're also going to try to standardize on voltage as well...

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.

[Shu]

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

[AllenGregoryIV]

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

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.

[Kevin Sevcik]

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.

[Ether]

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.

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

[AllenGregoryIV]

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

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.

[Ether]

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.

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

[Aren_Hill]

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




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

[Ether]

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

Oh well. How about leave it at 1:1 and stick a Talon on there and use this (http://www.chiefdelphi.com/media/papers/2702) to give it a 1.92 ms pulse width ?

[ttldomination]

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

- Sunny G.

[AllenGregoryIV]

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

- Sunny G.

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.

[AllenGregoryIV]

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




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.

[Ether]

Ether, what exactly are you trying to get us to test?

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.

[AllenGregoryIV]

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 speeds by changing the voltage. If you mentioned that in an earlier post, I missed it.





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 (http://3847.blogspot.com/2013/01/day-12-drive-train-is-on-ground.html) 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.

[GilaMonsterAlex]

Very cool!

[AllenGregoryIV]

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 (http://www.spectrum3847.org/resources/Photos/100_0541.JPG)
Photo 2 (http://www.spectrum3847.org/resources/Photos/100_0544.JPG)
Photo 3 (http://www.spectrum3847.org/resources/Photos/100_0545.JPG)
Photo 4 (http://www.spectrum3847.org/resources/Photos/100_0546.JPG)

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.

[brianwech]

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.

[AllenGregoryIV]

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.

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

[AllenGregoryIV]

Versaplanetary 1:1 Conversion Instructions (http://3847.blogspot.com/2013/01/versaplanetary-11-conversion.html)

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

[G Fawkes]

Versaplanetary 1:1 Conversion Instructions (http://3847.blogspot.com/2013/01/versaplanetary-11-conversion.html)

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

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?

[AllenGregoryIV]

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?

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.

[EricLeifermann]

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....

[Paul Copioli]

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

[AllenGregoryIV]

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.)

[AllenGregoryIV]

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 (http://content.vexrobotics.com/vexpro/pdf/VEXpro_VersaPlanetary_UserGuide_20130122.pdf)

[Robo Hamsters]

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?

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

[s_forbes]

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!

[AllenGregoryIV]

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!

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.

[falconmaster]

Thanks Team Spectrum!
We have one now
http://www.youtube.com/watch?v=zggvDqIy9Wk&feature=youtu.be

[Kevin Sevcik]

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.

[AllenGregoryIV]

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.

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.

[philso]

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

[AllenGregoryIV]

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

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.

[philso]

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.

[AllenGregoryIV]

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.

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

[Kevin Sevcik]

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.

[philso]

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.

[JVN]

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.

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

-John

[brianwech]

Thanks Team Spectrum!
We have one now
http://www.youtube.com/watch?v=zggvDqIy9Wk&feature=youtu.be

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.

[AllenGregoryIV]

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

-John

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)

[Kevin Sevcik]

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)*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.

[JVN]

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.

Depends entirely on the reduction, and output shaft configuration. Check out the loading tables at the end of this guide:
http://content.vexrobotics.com/vexpro/pdf/VEXpro_VersaPlanetaryLoadRatings_20130107.pdf

[AllenGregoryIV]

Depends entirely on the reduction, and output shaft configuration. Check out the loading tables at the end of this guide:
http://content.vexrobotics.com/vexpro/pdf/VEXpro_VersaPlanetaryLoadRatings_20130107.pdf

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

[AllenGregoryIV]

Instructions are up on our blog

http://3847.blogspot.com/2013/01/versaplanetary-cimminicim-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.

[Alex Cormier]

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

[AllenGregoryIV]

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

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.

[Kevin Sevcik]

Depends entirely on the reduction, and output shaft configuration. Check out the loading tables at the end of this guide:
http://content.vexrobotics.com/vexpro/pdf/VEXpro_VersaPlanetaryLoadRatings_20130107.pdfI 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?

[AllenGregoryIV]

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

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

[falconmaster]

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 (http://3847.blogspot.com/2013/01/day-11-ultimate-ascent-shooter-testing.html) with full specs on the shooter configuration.

Youtube Video (http://www.youtube.com/watch?v=oTFTWgB1cY4)

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!

[AllenGregoryIV]

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!

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.

[Ether]

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.

[AllenGregoryIV]

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.




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

[Ether]

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

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.

[Kevin Sevcik]

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.

[RRLedford]

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

.

[falconmaster]

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.

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!

[Kevin Sevcik]

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.

[falconmaster]

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.

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?feature=player_embedded&v=Jc8g9WMoQ2o

[ttldomination]

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?feature=player_embedded&v=Jc8g9WMoQ2o

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.

[falconmaster]

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.

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.

[The_ShamWOW88]

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!

[G Fawkes]

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.

[falconmaster]

http://www.youtube.com/watch?v=PuX7eZw-D5Q&feature=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

[AllenGregoryIV]

http://www.youtube.com/watch?v=PuX7eZw-D5Q&feature=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

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.

[Ether]

Ratios of gear boxes go 5 to 1, 4 to 1, 1 to 1 order of motors is Bag, am, bag

The farthest we can shoot is 27 feet

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.

[falconmaster]

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.




will get that on Sunday

[falconmaster]

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=wGp3Mgknh8I&feature=youtu.be

[Akash Rastogi]

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=wGp3Mgknh8I&feature=youtu.be

Very nicely done.

[falconmaster]

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.

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

[Ether]

Ok now we did 5, 3, 1 ratio

Shooting farther!

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

[falconmaster]

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

[Bob Steele]

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

-John

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

R

[Ether]

isn't it illegal to trim the shaft of the motor down?


4.1.7.2 R33-A

[AllenGregoryIV]

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

R

R33
The integral mechanical and electrical system of any motor may not be modified. Motors, servos, and electric solenoids used on the ROBOT shall not be modified in any way, except as follows:

The mounting brackets and/or output shaft/interface may be modified to facilitate the physical connection of the motor to the ROBOT and actuated part.
The electrical input leads may be trimmed to length as necessary.
The locking pins on the window motors (P/N: 262100-3030 and 262100-3040) may be removed.
The connector housings on the window motors (P/N: 262100-3030 and 262100-3040) may be modified to facilitate lead connections.
The Integrated Encoder Module (P/N: 276-1321) may be installed on the VEX 2-wire Motor 393 (P/N 276-2177).
The VEX 2-wire Motor 393 (P/N: 276-2177) gears may be changed or replaced per the Supplier instructions.


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

[JVN]

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

R

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

[JohnSchneider]

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

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

[Ian Curtis]

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

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

[s_forbes]

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

Unfortunately, 2:1 is not an easy off-the-shelf gear ratio to come by. These small wheel shooters are super easy to build with a vex planetary and just about any kit motor. Available reductions are 1:1, 3:1, 4:1, 5:1, 10:1 and any combination of those you would like. You can still adjust the tangential velocity of the wheels by changing wheel size (2", 3", 4", 6" are easy from Banebots) or input motor. Bag motor spins at 14k rpm, AM motor at 16k, and Banebots 550 at around 19k Our best setup at the moment is a 5:1 Bag, 3:1 AM, and 1:1 Bag.

Just looking at the math, it's obvious we have a lot of slipping on the last wheel. By my calculations the tangential velocity of a 3" wheel on a 1:1 Bag motor is roughly 175 ft/sec. If a frisbee had no slippage when contacting a wheel in this type of shooter, I would expect it to leave at about 85 ft/second! This is waaay higher than what we are seeing, so I have no doubt that there is a lot of slipping going on.

Something interesting to note: we put a new frisbee into our two wheeled shooter (3:1 Bag, 1:1 Bag) and analyzed the marks left by the shooter wheels afterwards. It looked to me like the 3:1 wheel had more slippage than the 1:1 wheel, since the 3:1 had a shorter 'burn' mark left on the frisbee and shorter overall contact period.

Also interesting to note: given the frisbee compression and wheel spacing involved, the frisbee contacts two adjacent shooting wheels for a substantial amount of time. I'm not sure exactly how they all interact at this point...


TL;DR: I gave up on calculating this stuff, we're just going to go with quantitative results! Also, I need a better high speed camera.

[Ether]

Something interesting to note: we put a new frisbee into our two wheeled shooter (3:1 Bag, 1:1 Bag) and analyzed the marks left by the shooter wheels afterwards. It looked to me like the 3:1 wheel had more slippage than the 1:1 wheel, since the 3:1 had a shorter 'burn' mark left on the frisbee and shorter overall contact period.

Trying slowing both motors down, to get faster exit speed. Easy enough to do: run them with motor controllers instead of straight off a battery.

[falconmaster]

Trying slowing both motors down, to get faster exit speed. Easy enough to do: run them with motor controllers instead of straight off a battery.




We will try slowing down the last motor and then experiment with the others as well. Thanks!

[Kevin Sevcik]

You can also try speeding up the second wheel by putting in a BB RS-550. Or for prototyping purposes, one of the super-powered FP 801-0673 motors from last year. We prototyped with a FP and were getting some pretty impressive velocity. Mind you, we also have a larger wheel spacing, which means less time with the 'bee contacting two wheels.

[Ether]

You can also try speeding up the second wheel...

Better yet:

a) remove wheels 2 and 3, and adjust the speed of wheel 1 until you get the fastest exit speed (call it s1), then

b) keeping wheel 1 at speed s1, add wheel 2 and adjust its speed until you get the fastest exit speed (call it s2), then

c) keeping wheels 1 and 2 at speeds s1 and s2, add wheel 3 and adjust its speed until you get the fastest exit speed.

[sdcantrell56]

Better yet:

a) remove wheels 2 and 3, and adjust the speed of wheel 1 until you get the fastest exit speed (call it s1), then

b) keeping wheel 1 at speed s1, add wheel 2 and adjust its speed until you get the fastest exit speed (call it s2), then

c) keeping wheels 1 and 2 at speeds s1 and s2, add wheel 3 and adjust its speed until you get the fastest exit speed.




Most logical process for dialing in the shooter that I have seen yet.

[billbo911]

Better yet:

a) remove wheels 2 and 3, and adjust the speed of wheel 1 until you get the fastest exit speed (call it s1), then

b) keeping wheel 1 at speed s1, add wheel 2 and adjust its speed until you get the fastest exit speed (call it s2), then

c) keeping wheels 1 and 2 at speeds s1 and s2, add wheel 3 and adjust its speed until you get the fastest exit speed.




This is where a Chronograph (http://www.chiefdelphi.com/forums/showthread.php?t=110940&page=3&highlight=velocity) will come in really handy!
Whether you use of a single sensor or dual sensor doesn't matter, either will take out the subjectivity of the measurement and just give you solid measurements.

[Bob Steele]

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

While you are talking to them ask them about this law from Texas.....

If two trains going in opposite directions on the same track meet each other, one can't move until the other does.

:p

Thanks for the clarification on the FIRST rule ...

[Andy Brockway]

Thanks to all have posted to this thread. We tested our version last night.

We had been running two CIMs at 1:1 with 6" wheels with mediocre results. We could score in the high goal but only if we were close to the wall.

Last night we ran the 2-7/8" Bane Bot wheels. Our set up is BB550 motors at a 19:46 reduction. Two wheels 4" apart. The disk is loaded at about 12" off the floor with an angle of about 40 degrees. Running the motors at 50% shot the disks over the top of the high goal from about 17' away. Higher speeds did not change the performance much.

We started with 10-3/4" spacing but were not happy so we added a piece of 1/4" poycarbonate. Current spacing is 10-1/2". No additional friction material.

[Kevin Sevcik]

Thanks to all have posted to this thread. We tested our version last night.

We had been running two CIMs at 1:1 with 6" wheels with mediocre results. We could score in the high goal but only if we were close to the wall.

Last night we ran the 2-7/8" Bane Bot wheels. Our set up is BB550 motors at a 19:46 reduction. Two wheels 4" apart. The disk is loaded at about 12" off the floor with an angle of about 40 degrees. Running the motors at 50% shot the disks over the top of the high goal from about 17' away. Higher speeds did not change the performance much.You forgot the other critical variable. What compression are you running?

[dbonar]

Thanks for all the discussion!

New shooter last night. Slow wheel is a CIM with a 2.5" soft neoprene wheel (1:1). Fast wheel is a mini-CIM with a 4" soft neoprene wheel (1:1). Compression and the spacing between the wheels are not optimized yet. We've ordered a taller 4" wheel and installing a top shield as the frisbee is definitely rising as it goes through. While we don't have the rotational speed that some teams are getting we managed a 53" distance (parallel to the floor start) before optimization.

[Madison]

Here's some video of us testing our own variation of this idea. I'm not yet thrilled with how it's working out. We're not getting a lot of distance out of it.

http://www.youtube.com/watch?v=FR7ppSZ7VS0

The video shows a few different tests spliced together. I didn't edit out anything bad -- including language, thus the dumb music :) -- so what you see is what we saw.

In each subsequent test, we're dialing back power to the wheels.

The details:
Input wheel -- Banebots RS550 motor through a 3:1 Versaplanetary transmission driving 2 .8" thick, green Banebots wheels.
Output wheel -- BAG Motor through a 1:1 Versaplanetary transmission driving 4 .4" thick, orange Banebots wheels.
Bottom surface -- 1/4" delrin sheet
Wall -- 1x1x.063" Aluminum tube with 1" wide urethane flat belting double-sided taped to the inside face.
Compression -- 3/4" compression, I believe.
Loader -- 6" stroke, 3/4" bore pneumatic cylinder
Angle -- 30 degrees
Exit Height -- 22"

Any thoughts?

[falconmaster]

Thanks to all have posted to this thread. We tested our version last night.

We had been running two CIMs at 1:1 with 6" wheels with mediocre results. We could score in the high goal but only if we were close to the wall.

Last night we ran the 2-7/8" Bane Bot wheels. Our set up is BB550 motors at a 19:46 reduction. Two wheels 4" apart. The disk is loaded at about 12" off the floor with an angle of about 40 degrees. Running the motors at 50% shot the disks over the top of the high goal from about 17' away. Higher speeds did not change the performance much.

We started with 10-3/4" spacing but were not happy so we added a piece of 1/4" poycarbonate. Current spacing is 10-1/2". No additional friction material.

We found the spacing to be very sensitive, we see best results at 10 and 3/8" with the banebot wheels.

[Bob Steele]

Is anyone seeing any statistical/quantifiable difference between results when you compare the different banebot wheels (orange/green/blue)?

[AllenGregoryIV]

Is anyone seeing any statistical/quantifiable difference between results when you compare the different banebot wheels (orange/green/blue)?

I don't have the data but we were measuring better distances with the green wheels but they were getting damaged by the discs to quickly for us. The blue wheels weren't that of a much difference in distance.

[Bob Steele]

I don't have the data but we were measuring better distances with the green wheels but they were getting damaged by the discs to quickly for us. The blue wheels weren't that of a much difference in distance.

thanks for the information!
One other thing.
Do you find that the Versaplanetary gear boxes get hot while you are doing your shooting testing?

We set up two tonight and it seemed that they were pretty hot after a relatively short time.

thanks

[CalTran]

thanks for the information!
One other thing.
Do you find that the Versaplanetary gear boxes get hot while you are doing your shooting testing?

We set up two tonight and it seemed that they were pretty hot after a relatively short time.

thanks

We're running BAG motors through VERSAPlanetary gearboxes at 3:1 entry and 1:1 exit, both driving 2.875" blue banebot wheels off a .5" hex shaft. The 3:1 doesn't change temperature too terribly. The 1:1 gets fairly warm rather quickly. Not sure if it's something to be concerned about or not right now. Still have yet to put our shooter prototype through it's paces. Will do extensive testing tomorrow and Thursday.

[Bob Steele]

We're running BAG motors through VERSAPlanetary gearboxes at 3:1 entry and 1:1 exit, both driving 2.875" blue banebot wheels off a .5" hex shaft. The 3:1 doesn't change temperature too terribly. The 1:1 gets fairly warm rather quickly. Not sure if it's something to be concerned about or not right now. Still have yet to put our shooter prototype through it's paces. Will do extensive testing tomorrow and Thursday.

We set up two to run on the BB 550 motors (a 5:1 and a 1:1) and both seemed to get hot very quickly. We followed the directions on attaching the motors ... but it didn't feel quite right for either one... a little too much binding when we clamped down the screws...

We followed the directions on how to assemble from the website..

We are doing the same thing you are with the same size banebot wheels and the hex shafts... we will try more tomorrow night.
thanks for the help!!

[Dale]

Bob,
It might also have to do with how the gearboxes were lubricated. Too much grease can cause of a lot of internal resistance and, of course, too little isn't a pretty sight unless you like metal dust. We use about a pea sized amount of grease per stage, either Superlube or Lithium is what we use but everyone has their favorite. Ours get warm but certainly not crazy hot.

[Botwoon]

thanks for the information!
One other thing.
Do you find that the Versaplanetary gear boxes get hot while you are doing your shooting testing?

We set up two tonight and it seemed that they were pretty hot after a relatively short time.

thanks

Our 1:1 boxes get uncomfortably hot after about 30 seconds or so. We definitely won't be running them full time.

[AllenGregoryIV]

I have found them to get warm but never as hot as our drive CIMs or anything like that. I think most of the 1:1 heat is from the bearings but I have no way to know that.

One of the reasons we are choosing to run BAG motors is so far they have taken all the heat we have thrown at them, which is mostly being stalled several times in a row from failed collector tests. We ran BB550 on our collector last year and stalled it once for 20 secs or so and smoked the motor. The BAGs are expensive but we don't have to replace it this competition season it'll be worth it.

I'm interested to see how the bearings in the VPs hold up over the course of the season. We'll have spares gearboxes on hand but hopefully won't have to use them.

[TerryS]

We set up two to run on the BB 550 motors (a 5:1 and a 1:1) and both seemed to get hot very quickly. We followed the directions on attaching the motors ... but it didn't feel quite right for either one... a little too much binding when we clamped down the screws...

We followed the directions on how to assemble from the website..


Bob, we're running the same ratios as you using the AM 9015 motors. We had some binding issues initially too. I emailed Vex and got an immediate reply from Paul Copioli with the very helpful technique to loosen the mounting bolts slightly and run the motor. When the motor and gearbox sound like they're running smoothly tighten the screws. That technique solved our binding issues.

By the way, if anyone else is using a AM 9015 motor from this year's KOP with the VerasPlanetary you'll probably need to use the 1/4" spacers with any gear ratio as the knurled length of the shaft is shorter than an AM 9015 motor from last year. Paul said they designed the AM 9015 collar to grip the knurling, but with the shorter knurled length it's trying to grip an un-knurled portion of the shaft. The 1/4" spacers put the knurling in the collar.

A very big mahalo to Team Spectrum for sharing their design! We were already headed down the same path, but learning about the Banebots wheels with the VersaPlanetary gearboxes sure got us to our final design a lot quicker.

In our latest round of testing we shot some upside down discs successfully into the middle and high goals from up close using the same wheels speeds as a right-side up disc without a cover. Upside down shooting was more sensitive to feeding though. If it wasn't fed quite right the disc would pop up from the first wheel. We'll probably add a cover to take care of this issue.

[TD78]

We set up two to run on the BB 550 motors (a 5:1 and a 1:1) and both seemed to get hot very quickly. We followed the directions on attaching the motors ... but it didn't feel quite right for either one... a little too much binding when we clamped down the screws...

We followed the directions on how to assemble from the website..

We are doing the same thing you are with the same size banebot wheels and the hex shafts... we will try more tomorrow night.
thanks for the help!!

Bob, when I set up a BB 550 (motor was purchased two years) in a 10:1 VP, I had trouble getting the gearbox to spin while powered. I could turn the shaft by hand (with a wheel on it - slightly difficult), but when I put it on a power supply, the shaft wouldn't spin at all and the current spiked rather quickly. I did not find this problem with the BAG motor installed 1:1. After much testing individual components, I eventually spaced the BB 550 motor plate from the gearbox with thin washers. This appeared to relieve some pressure between the motor (either the shaft or the face of the motor) and the gearbox. I notified VEX support and Paul sent me two things to try:

"1. As you suspect, the RS-550 shaft that you have may be a bit longer than we have tested and the end of the shaft may be pressing against the gear. To test this, please remove the input sun gear while the motor is installed to see if it sticks into the same space the gear should be.

2. The clamping hub and bolts are fighting each other. In order to get around this, try only using to bolts to mount the motor plate and tighten them after you have tightened the coupler."


I did not try either though, because my team had decided to go with a double BAG motor setup. Maybe you're seeing something similar?

[G Fawkes]

The versaplanetary gearboxes come "fully assembled". Should we be opening them up and adding grease?

[artdutra04]

The versaplanetary gearboxes come "fully assembled". Should we be opening them up and adding grease?Yes, we recommend a light coating of white lithium grease to ensure longevity.

[CalTran]

I just put our motors and gearboxes through an "intensive" test. 12 volts straight from a battery to the 3:1 gearbox and the 1:1 gearbox (Both driving BAG motors.) for 1 minute 25 seconds. 3:1 Gearbox is noticeably warmer than the 1:1 gearbox. BAG Motors are warm but nothing to be concerned of, if their construction mimics that of a CIM. Do not have access to any temperature sensing probes.

*3:1 gearbox was freshly greased with white lithium grease (NLGI #2). 1:1 gearbox has not been greased yet outside of stock greasing.

[Paul Copioli]

All,

There are several items that contribute to heat in a VersaPlanetary gearbox. The #1 thing that is different than other gearboxes you are used to is the thin wall of the ring gear section. The ring gear is aluminum and very thin so it conducts the heat very quickly and gets hot quickly. In addition, the thermal mass of the aluminum is less than the steel gears and bearings so it will get hotter much faster than the internal steel gears.

Also, the output shaft is also aluminum to that thing gets pretty hot, too.

The BAG motor has the same internal construction as a CIM motor and that is why it is able to dissipate heat in a similar way. It does not rely on convection cooling like a RS550, RS775, or AM-9015 so it is happy to remain at an elevated temperature. However, the aluminum VersaPlanetary case is sucking a lot of heat from the motors and acting as a heat sink. The VersaPlanetary housing gets hot, but it is nothing to be concerned about.

The bearing speed rating is over 20,000 RPM so this application should not over task the bearings.

In short, the gearbox getting hot is primarily related to the thin aluminum case and is not a concern.

Paul

[AllenGregoryIV]

All,

There are several items that contribute to heat in a VersaPlanetary gearbox. The #1 thing that is different than other gearboxes you are used to is the thin wall of the ring gear section. The ring gear is aluminum and very thin so it conducts the heat very quickly and gets hot quickly. In addition, the thermal mass of the aluminum is less than the steel gears and bearings so it will get hotter much faster than the internal steel gears.

Also, the output shaft is also aluminum to that thing gets pretty hot, too.

The BAG motor has the same internal construction as a CIM motor and that is why it is able to dissipate heat in a similar way. It does not rely on convection cooling like a RS550, RS775, or AM-9015 so it is happy to remain at an elevated temperature. However, the aluminum VersaPlanetary case is sucking a lot of heat from the motors and acting as a heat sink. The VersaPlanetary housing gets hot, but it is nothing to be concerned about.

The bearing speed rating is over 20,000 RPM so this application should not over task the bearings.

In short, the gearbox getting hot is primarily related to the thin aluminum case and is not a concern.

Paul

Thanks for clearing that up Paul.

[billbo911]

Here is our final shooter design before mounting it on the robot.
Before the hood was added today, we were able to consistently shoot at 31 ft./sec. We will optimize it now that the actual assembly is complete. We hope to squeeze another 5 Ft./sec out of it.

http://www.youtube.com/watch?v=cpHcMgwtmYk&feature=youtu.be

[AllenGregoryIV]

Here is our final shooter design before mounting it on the robot.
Before the hood was added today, we were able to consistently shoot at 31 ft./sec. We will optimize it now that the actual assembly is complete. We hope to squeeze another 5 Ft./sec out of it.

http://www.youtube.com/watch?v=cpHcMgwtmYk&feature=youtu.be

Awesome video, I like the feeder, very simple. What are the specs? 3:1 and 1:1? Compression? Wheel Separation?

[IndySam]

Here is our shooter as of Monday. (http://www.youtube.com/watch?v=N03kkVlqRjM&feature=youtu.be) Standard stuff, 1:1, 3:1, bag motors 'bout 3/8 compression right now with a rubber strip on opposite side.

We designed it to use two or three wheels but found the third wheel added little for the amount of complication it added. We also tried 3" Colsons but switched back to the Bane Bots. You never know, durability testing may make the Colsons more attractive.

Sorry for the shaky cell phone video.

Big thanks to the folks at 3847 and everyone else who shared on this thread.

[billbo911]

Awesome video, I like the feeder, very simple. What are the specs? 3:1 and 1:1? Compression? Wheel Separation?

Yes, 3:1 and 1:1. Wheel separation is approximately .25". Currently the compression is around .5", but we will be optimizing that using a chronograph today, getting actual numbers instead of just observation.
Although, even if we leave it exactly where it is, it is already acceptable for our game play strategy.

[Phyrxes]

Question for those of you running a close spacing between the wheels do you notice any issues with discs being in contact with both? Currently our wheels are approximately 1.5" apart and I'm wondering if it its worth re-manufacturing the attachment at this point.

Same as most people: 1:1 and 3:1 Bag motors, orange BB wheels, and using a piece of of roughtop on the fence with about .25" compression.

[CalTran]

Question for those of you running a close spacing between the wheels do you notice any issues with discs being in contact with both? Currently our wheels are approximately 1.5" apart and I'm wondering if it its worth re-manufacturing the attachment at this point.

Same as most people: 1:1 and 3:1 Bag motors, orange BB wheels, and using a piece of of roughtop on the fence with about .25" compression.

I'm thinking the same thing. There's currently, on ours, something like 2.5 nineteen our wheels, as we were discovering significant wear on our 1:1 wheel. Same setup as others - 3:1 and 1:1 bag motors, 2.87 blue banebots wheels, 9/16th compression, gaffers tape on the compression wall, AND A COVER over the wheel (picture to be posted in an hour) and were getting absurdly less distance than anyone else

[sdcantrell56]

Question for those of you running a close spacing between the wheels do you notice any issues with discs being in contact with both? Currently our wheels are approximately 1.5" apart and I'm wondering if it its worth re-manufacturing the attachment at this point.

Same as most people: 1:1 and 3:1 Bag motors, orange BB wheels, and using a piece of of roughtop on the fence with about .25" compression.


We aren't running tiny wheels but smaller than most, and it was my engineering intuition that says having the frisbee touching both wheels has to be detrimental to overall performance as that pretty much necessitates one wheel slipping. Ours is designed so this isn't possible and the shooter does seem to perform quite well with minimal wear on the green banebots wheels.

Additionally, roughtop as a backstop is probably not the best material. Roughtop actually has pretty poor friction on plastics

[AllenGregoryIV]

We aren't running tiny wheels but smaller than most, and it was my engineering intuition that says having the frisbee touching both wheels has to be detrimental to overall performance as that pretty much necessitates one wheel slipping. Ours is designed so this isn't possible and the shooter does seem to perform quite well with minimal wear on the green banebots wheels.

Additionally, roughtop as a backstop is probably not the best material. Roughtop actually has pretty poor friction on plastics

This seems like it would be true. The initial prototype design came about for the design requirement of being able to mount our shooter/collector on a lift so it had to be insanely small and light. I'm glad other teams have found a use for it but our specs were never meant to be taken as optimal for all situations. In fact we only ever plan to shoot from behind the pyramid as our max distance, most of our shots should only travel about 4 feet total before entering the goal.

[rai337]

Thank you very much about this post, we use a small wheeled shooter too now, and it can shoot up to 40 fit ( 2 bag cims, no gears )!
you helped us alot! :)

[CalTran]

Thank you very much about this post, we use a small wheeled shooter too now, and it can shoot up to 40 fit ( 2 bag cims, no gears )!
you helped us alot! :)

What compression, wheels, and wheel separation are you using?

[rai337]

What compression, wheels, and wheel separation are you using? every wheel uses one bag motor with no gear, and i dont realy sure about the wheels, i never saw any wheels like them, they made of some kind of spong .. here's a picture we got in fb, it doesnt explain alot, but still..
http://www.facebook.com/photo.php?fbid=10151331482496849&set=a.10150608423026849.381078.283755611848&type=1&theater

[CalTran]

i dont realy sure about the wheels, i never saw any wheels like them, they made of some kind of spong

Something or another like this? (http://www.hobbyking.com/hobbyking/store/__5614__Light_Foam_Wheel_Diam_110_Width_30mm_.html ) Our team used a similar product back in 2010 for our ball magnet. Worked great.

[IndySam]

Because of the buggy BAG motor problem, we have switched our motors over to a BB775 at 3:1 for the first shooter, and a AM-9012 1:1 for the second wheel. The first wheel is at 90% power while the second is at 85%.

We are shooting the high goal from the back of the pyramid with ease so we are pleased with the result.

We also made the compression on the first wheel about 3/16 less than the first wheel to aid in our ground loading. This change did not effect distance at all.

[Andrew Zeller]

While this post is regarding using the VersaPlanetaries with a pneumatic wheel, I figured I would post it here after all the other postings about powering shooter wheels off of the VersaPlanetary.

My team's competition robot is currently running a two 8" pneumatic wheel linear shooter directly driven by CIM motors that were attached to a machined step shaft via a coupling. We found this setup to cause extreme vibrations and our small couplings would often come loose.

I believed that these vibrations (which I thought had to do with the lack of concentricity with our setup) also caused y-variability with our shooter so on our practice robot we are trying to run the 8" pneumatic wheels directly off of the 3:1 VersaPlanetary with an RS-550 on each. Looking at the motor curves, I figured that we could get close to the ~4500 r/min that we had with the CIM with this setup. Perhaps I am wrong.

When we tried powering the VersaPlanetary (with the Pneumatic wheel attached via 1/2" shaft and 1/8" keyway) using an FRC battery, the wheel would quickly get up to speed however after about 10 seconds a burning smell developed and we could see smoke coming out of the gearbox, not the motor.

We applied white-lithium grease moderately and did our best to follow the instructions for assembling the gearbox and motor.

From those more experienced than I, should I even be trying to direct drive a pneumatic wheel with the VersaPlanetary at 3:1 with the 550? Do you even think I could get the wheel up to 5000 r/min?

On to the smoke problem- should I try spacing out the motor mounting plate? It is not too hard to spin the output shaft by hand however it is pretty jerky. We inspected the gearbox afterwards and it appeared fine. Should we just try reassembling the motor onto the gearbox?

Also, it heated up quickly when powered on.

Hopefully Paul Copioli will see this and offer some advice.

Thanks!

Bob, when I set up a BB 550 (motor was purchased two years) in a 10:1 VP, I had trouble getting the gearbox to spin while powered. I could turn the shaft by hand (with a wheel on it - slightly difficult), but when I put it on a power supply, the shaft wouldn't spin at all and the current spiked rather quickly. I did not find this problem with the BAG motor installed 1:1. After much testing individual components, I eventually spaced the BB 550 motor plate from the gearbox with thin washers. This appeared to relieve some pressure between the motor (either the shaft or the face of the motor) and the gearbox. I notified VEX support and Paul sent me two things to try:

"1. As you suspect, the RS-550 shaft that you have may be a bit longer than we have tested and the end of the shaft may be pressing against the gear. To test this, please remove the input sun gear while the motor is installed to see if it sticks into the same space the gear should be.

2. The clamping hub and bolts are fighting each other. In order to get around this, try only using to bolts to mount the motor plate and tighten them after you have tightened the coupler."


I did not try either though, because my team had decided to go with a double BAG motor setup. Maybe you're seeing something similar?

[Paul Copioli]

Andrew,

Don't be so sure that the smoke isn't coming from the motor. The VP is designed to have vents to the motor form the motor mounting plate. Smoke form the motor could definitely look like it is coming from the VP.

With that said, my team is running 2 VPs on our shooter with 8" pneumatic tires and have seen no such smoke. We are using RS775 motors with 5:1 and 3:1 There really isn't anything inside the VP that would smoke very long before seizing.

I suggest you look at the current the motor is drawing while just attached to the VP. Some people have reported problems getting the RS550 motor lined up properly while installing into the gearbox. That could be causing excessive loading on the motor causing it to overheat.

Paul

[pfreivald]

When we were first running our shooter with 3:1 Versaplanetaries with BAG motors, the gearboxes would get very hot, while the motor (and the wires to the motor) were cool. We tweaked the spacing of the sun gear on the output shaft just a little, and that solved the problem.