motor for ball Shooter?

[excel2474]

I'm not sure what motor to use for a ball shooter. We already have the fisher price motors reserved for a different function. I thought about using a CIM motor, but I wasn't sure how to mount it or what gearbox to use. Any help would be great thanks. Pics would be nice to if you have link to some of your old robots.

[joeweber]

CIM will work great, two even better. Try a six inch wheel direct drive. If you tie the two together with gears or belts it will stablize the shooting force. When the ball hits the two spining wheels it will be gone...

[excel2474]

CIM will work great, two even better. Try a six inch wheel direct drive. If you tie the two together with gears or belts it will stablize the shooting force. When the ball hits the two spining wheels it will be gone...

ok great, thanks for that. So if I just connect the wheel directly to the motor without any chains, and I only use one motor, do you think that would be ok to. I don't really need it to go that far.

[waialua359]

a direct drive from the CIM motor should be sufficient.

[joeweber]

One may not have enough power, it may stall out the motor or slow it down unless you are spinning two wheels. But two will do a great job. 2006 we used one large cim which is about 2500 rpms (35ft no problem) and it did the job, the small CIM is about 5300 rpm (less power & more speed) & with two you will have the power and speed.
With these lighter balls one may do it.

We are using two CIM'S this year and the 6 in skyway wheels. Remember you can only shoot as far as your camera can see.

[Molten]

Just a suggestion, it seems you are all assuming that he is using the motor for a softball style of shooter. If he is using it in a different way, then the advice you gave him will be of little help.

[dtengineering]

We were able to fire poof balls the maximum permissable distance in 2006 using an FP geared 5:1 using a banebots planetary gearbox and a single 8" wheel. So far we have found that an 8" wheel spinning at about 1000-1500 rpm puts a nice bit of velocity (and backspin) on the orbit ball. The downside was that the 2006 shooter would slow down after two shots and would take a second or two to come back up to full speed.

Jason

[s_forbes]

So far we have found that an 8" wheel spinning at about 1000-1500 rpm puts a nice bit of velocity (and backspin) on the orbit ball.

We're coming to similar findings as well. Our prototype (here (http://www.youtube.com/watch?v=ZIlRWFW9jsk)) spins an 8" wheel at 1300 rpm and spits an orbit ball a good distance with a ton of backspin. The time it takes to spin back up looks short enough to possibly shoot 3 or 4 balls a second. This is with about a 4:1 reduction off of a single CIM motor.

I don't see the need to shoot the ball any further than 10 feet or so, but I may be wrong (it's happened before...).

[Lesman]

I reccomend rollers not wheels, or at least multiple wheels next to each other. 6" diameter wheels opposite each other tend to catch the ball in the holes which slows it down significantly.

[Elgin Clock]

In 2006 we used 2 of the CIM motors directly driven into a 6" Skyway wheel (similar to this year's wheels, but with a much more grippy surface on them.)

They threw the Poof balls very far that year at a nice speed, but your main factor with shooting this year's balls will be how the shooter wheel or other surface will interact with the "not-so-solid" ball.

Should be interesting seeing the shooters that teams come up with this year.
I know I want to see some in action!

I'll try to get a nice up-close pic of our shooter mechanism from 2006, as all of the pics I've located so far of that bot are not close-ups.

[GaryVoshol]

fire poof balls the maximum permissable distance Oh oh. What do you think the chances are of that rule coming back in a Team Update?

[Jimmy Cao]

IMO a single CIM motor will have plenty of power for what you're doing. A CIM is roughly as powerful as 2 FischerPrices, and it is more resilient to stall/heavy usage. If you don't need any reduction, just direct drive the CIM. A rather small transmission for the CIM that can provide decent reduction would be the DeWalt planetary transmission (see CD Whitepapers, All About Dewalts, if I recall the name properly)

Depending on how your shooter works, a single RS545 (Banebots) might also be enough, geared properly. Banebots sells 4:1, 5:1, 16:1, 20:1, 25:1 (?) 36mm transmissions for this motor. Be careful, however, since these motors do not like being stalled and will heat up rather quickly if they're forced to work hard. They will die on you if overworked.

[MrForbes]

We're looking into using the toothed belt for the small amount of speed reduction we think we want for a CIM powered shooter. Or possibly even a V belt, pulleys and belts available at your local hardware store.

Elgin: see the ball cannon thread

http://www.chiefdelphi.com/forums/showthread.php?threadid=71253

for videos

[team2061]

Is there a limit on cim motors this year?

[kirtar]

I have a hunch that it's four like last year (and because I read the rules)....

[team2061]

I have a hunch that it's four like last year (and because I read the rules)....

So I'm guessing that teams using cim motor for a shooter/cannon will only be using a total of two cim motors for their drive train

[Ryan Dognaux]

Fischer Price or CIMs are really your best bet. We've been prototyping all week in different configurations using last year's kit wheels. We were able to get a ball shooting beyond 15 feet, however, we don't really think we'll be going for that kind of distance in our final design.

As others have said, a direct drive from the small CIM would do just fine for shooting 5 - 10 feet. I would advise everyone to try out different materials as we've found that some materials react much better with the ball than others.

[thefro526]

I always like the design MARS 1523? used for their shooter in 2006. It would work great with these balls I think. A design like this would allow you to use a less powerful slower spinning motor like a bane bot.

[Jim E]

Thanks for the kind words about our 2006 robot design, Ball-istic.

MARS, Team 1523, accomplished that with a one-way bearing, a little bit of surgical tube, and a window motor. It wasn't a winning design of the season, but it was gentle on the game pieces and worked very well for us. It would even throw balloons without breaking them!

I'm not sure we need that kind of power in this year's game. 30 ft into the upper goal is a little too much. That center post on the trailer is going to prevent many a ball from staying in the trailer.

[joeweber]

We just made a test stand using two CIM motors direct drive with 6 in Skyway wheels. They were set at about 35 degrees (low ceiling) and were 4 ft off of the ground and we were able to land a ball in a trailer located 13 ft away. These were mounted horizontal and our final design will be vertical. I did notice that if a hole portion of the ball happened to hid the spinning wheels the distance was greatly reduced. We will be using four wheels to contact the ball to reduce this problem and may use 8 inch wheels instead of 6 inch. The CIM motors seemed to come back up to speed very quick with out gear reduction and a well balanced wheel.

[daltore]

We made a prototype last night with a wood frame holding (4) 4" RC racing wheels, the left and right of which were both direct-driven off of their own CIM. Unfortunately, these wheels were all off-roading wheels, so when we turned on the motors, the tires got really skinny and the wheel diameter doubled :ahh: It was pretty scary, but managed to shoot a regular inflatable ball about 60 feet, and the orbit ball around 10. When we stop using maximum speed and motorize the other two wheels and replace all of the tires with road flats, the ball should be a little better controlled (and the rig should be a little less insane).

For reference, the Fisher Price motors are 2/3 the power of the CIMs (1/3 horsepower). Due to the low-friction of the field, there's very little problem using them on a drive train, as long as you monitor the wheel speed vs. motor power to make sure something isn't jamming your wheel and burning up your motor (the magic smoke is hard to put back into the FP's, that's their drawback over the CIMs).

[Donut]

If you can afford to part with a CIM or 2 (and with the low traction this year you most likely can) I would recommend those for the shooter. They're easily the most powerful motors in the kit and have a high RPM if you don't want to gear them down much. There's also a number of transmissions available from AndyMark that will allow you to get different gear ratios if you need a larger reduction than what can be done with pulleys or sprockets easily.

Whatever configuration you use make sure to gear your motors low enough that they can get the wheel up to speed quickly and not jam. We had an effective tracking algorithm and driving robot in 2006 but the death of our system was an under geared shooter that could not fire a ball more than once every 2 seconds or it would jam.

We're going all out on our shooter this year, 2 CIMs in the current test setup and we're considering adding a third if we don't use it anywhere else. This is for our specific design though and I don't think that much power would be useful on most shooters.

[waialua359]

Fischer Price or CIMs are really your best bet. We've been prototyping all week in different configurations using last year's kit wheels. We were able to get a ball shooting beyond 15 feet, however, we don't really think we'll be going for that kind of distance in our final design.

As others have said, a direct drive from the small CIM would do just fine for shooting 5 - 10 feet. I would advise everyone to try out different materials as we've found that some materials react much better with the ball than others.

I think shooting (goal) for 15 ft is fine, if you can adjust and slow your CIM speed based on distance.
On reading another post about having a backspin on the shooter wheel, they made a huge difference, in our ability to score in the trailer.
Our team is hoping to finalize our wooden shooter design prototype tomorrow and work on a feed system. :)

[Cory]

One may not have enough power, it may stall out the motor or slow it down unless you are spinning two wheels. But two will do a great job. 2006 we used one large cim which is about 2500 rpms (35ft no problem) and it did the job, the small CIM is about 5300 rpm (less power & more speed) & with two you will have the power and speed.
With these lighter balls one may do it.

We are using two CIM'S this year and the 6 in skyway wheels. Remember you can only shoot as far as your camera can see.

A single CIM would actually be significantly more powerful than the single large CIM you used in 2006.

[Brandon Holley]

I am kind of surprised people are investing so much motor power in their shooters. 1 CIM seems like plenty of power to me.

Based off of our prototype shooter, 1 CIM spinning at 1:1 ratio with a 6 inch wheel threw the orbit ball ~30-35 feet, which seems to be awfully overkill for this game. This was feeding ball after ball right after another through the shooter wheel.

[sdcantrell56]

I am kind of surprised people are investing so much motor power in their shooters. 1 CIM seems like plenty of power to me.

Based off of our prototype shooter, 1 CIM spinning at 1:1 ratio with a 6 inch wheel threw the orbit ball ~30-35 feet, which seems to be awfully overkill for this game. This was feeding ball after ball right after another through the shooter wheel.

How much compression were you running on the ball? We seemed to have settled on 2"

[kurttruk820]

I am kind of surprised people are investing so much motor power in their shooters. 1 CIM seems like plenty of power to me.

Based off of our prototype shooter, 1 CIM spinning at 1:1 ratio with a 6 inch wheel threw the orbit ball ~30-35 feet, which seems to be awfully overkill for this game. This was feeding ball after ball right after another through the shooter wheel.

Can you provide details on your setup? Our prototype has one CIM per side @ 1:1, driving stacked 2008 KOP wheels spaced ~6" apart. A piece of ductwork is acting as a barrel to provide a little forward spin. At best, we've been able to hit targets as far as 15 ft.

We're planning on using wider, softer wheels in the final design to get more surface contact with the orbit ball and will be driving the entire system with 1 CIM.

[MrForbes]

What Brandon forgot to mention is that the NU-TRONs have been playing with ORBITS for a very long time, and have some magic secrets they can't tell us about :)

[Brandon Holley]

How much compression were you running on the ball? We seemed to have settled on 2"

We have a gap of 7.5", given the ball to be between 9"-9.375", from the numbers I've seen and the measurements I've taken, its around 1.5-2.0" compression.

[JesseK]

Thanks for the tips on the shooter motor slowdowns. We don't have a CIM available for the shooter, and our window motors are being used for our conveyor system. So we're down to the FP & Banebots motors for the shooter.

For our setup, we're considering 2 FP's into AM Planetaries (3.67:1) and a 1:1 pulley ratio off of that. The roller radius is probably going to be 1", and will not be a single roller but instead will be another sort of conveyor belt. The hope is that this gives the ball more acceleration time and contact area, therefore the holes have less impact on the distance. We don't want max distance as much as we want a consistent shot.

Does anyone see any glaring deficiencies or oversights with this setup?

Also, didn't I read somewhere that with AM plaction wheels you could put a 5" PVC pipe in between the separated wheel to create a much wider wheel? Or am I dreaming? I can't seem to find that anywhere on these forums or on AM's site -- but I think that'd be a better idea than mounting 4-5 skyway wheels side by side. Then you could also easily mount your own tread.

[lynca]

We have a gap of 7.5", given the ball to be between 9"-9.375", from the numbers I've seen and the measurements I've taken, its around 1.5-2.0" compression.

Does anyone have closeup pictures of a shooting prototype ?

How do you directly attach a CIM motor shaft to a 6 inch wheel (a picture would be sufficient as well) ?

[MrForbes]

I think there are some in our photo gallery. We used a transmission and a chain reduction on an 8" wheel. I think some reduction would be nice...we're planning on a 5" roller with 2.5:1 chain reduction on our first "real" shooter design.

[R.C.]

If you do use a cim make sure to put a reduction on it. Going 5500 rpms (free speed) is too high. Make sure to put atleast a 3:1 reduction. That will increase stall torque for the motor. That way the wheel won't slow down after firing a wheel. Also a 2 inch thick wheel should be used.

If you use a Fp. Then dual it and use the planetary from Andymark into a spur gearbox. Making the output speed the same as a 3:1 CIM. Also, you could possibly hex a custom AL or plastic wheel and direct drive it.

This is what we will probably do. Also how much compression are most teams gonna apply to the ball. More compression = higher risk of hurting the ball?:ahh:

[waialua359]

We have a gap of 7.5", given the ball to be between 9"-9.375", from the numbers I've seen and the measurements I've taken, its around 1.5-2.0" compression.

Your setup is very similar to what we have prototyped, but with less compression and a wider gap. That would probably explain the 30-35ft range as ours did not go quite as far.
How is your accuracy if you slow the motor speed for shorter distances to target?
Ours is quite accurate at the 15ft range, however, trying to make it into a trailer consistently while both our robot and the trailer moving with different orientations is another story.

I think a 1:1 CIM - shooter speed is fine without a reduction also.

[artdutra04]

How do you directly attach a CIM motor shaft to a 6 inch wheel (a picture would be sufficient as well) ?If you have a wheel which has one of the 1.875" 6x #10 hole patterns (like all of the AndyMark, IFI, Skyway wheels), just take an aluminum hub of your choice (either make your own with a 8mm hole, or buy this one (http://andymark.biz/am-0215.html) and ream out to 5/16" or O-drill hole*). Then take an 2mm broach (about $40 on McMaster - useful if you plan to do a lot of custom stuff with CIM motors), and broach the hub with a 2mm keyway. Attach CIM motor with 2mm machine key to the hub, and attach hub to the wheel.

Now this will cantilever the wheel off the motor, which may work for testing, but may not work well later on. To get past this, you can also make a shaft coupler than has two keyways (one 2mm, one 3/32" or 1/8") with the 2mm side bored to 8mm and the other end bored out to 3/8"-1/2"). Then use bearings or bushings on the shaft the motor is coupled to to support the wheels. If you are worried about keeping the shafts lined up, you can also use a Lovejoy connector here.

* Both 5/16" and O-drill are within 0.003" of 8mm, with 5/16" being undersized and O-drill being oversized. Or if you plan on making a lot of things adapt to the shaft of the CIM motor, just buy an 8mm drill bit, they're like $3-$5 on McMaster.

[Brandon Holley]

Can you provide details on your setup? Our prototype has one CIM per side @ 1:1, driving stacked 2008 KOP wheels spaced ~6" apart. A piece of ductwork is acting as a barrel to provide a little forward spin. At best, we've been able to hit targets as far as 15 ft.

We're planning on using wider, softer wheels in the final design to get more surface contact with the orbit ball and will be driving the entire system with 1 CIM.


I will post pictures tonight of our setup. The material were using on our drum is going to remain a secret for the time being because we are finding it to be a real difference maker in the effectiveness of our design.

The quick story is 1 CIM, 1:1 reduction through a chain and sprocket to a 6" spinning drum approx. 4.5" wide.

What Brandon forgot to mention is that the NU-TRONs have been playing with ORBITS for a very long time, and have some magic secrets they can't tell us about :)

Hahaha, you are on to us squirrel.

Does anyone have closeup pictures of a shooting prototype ?

How do you directly attach a CIM motor shaft to a 6 inch wheel (a picture would be sufficient as well) ?

Picture coming later tonight, but we mounted the CIM inside of our prototype shooter box, behind the lexan arc the ball travels around. Then on the outside of the box we ran a chain from the CIM motor shaft to the shaft the spinning drum is mounted to.

Your setup is very similar to what we have prototyped, but with less compression and a wider gap. That would probably explain the 30-35ft range as ours did not go quite as far.
How is your accuracy if you slow the motor speed for shorter distances to target?
Ours is quite accurate at the 15ft range, however, trying to make it into a trailer consistently while both our robot and the trailer moving with different orientations is another story.

I think a 1:1 CIM - shooter speed is fine without a reduction also.

The prototype we designed was made on a ShopBot (shopbottools.com). Its essentially just a CNC router. So we were able to cut nice arcs into the prototype. We put a bunch of arcs so we can slide a piece of lexan in and out (more compression and less compression) to tell us exactly what amount of compression worked the best. So far what we've seen is 7.5" to be the money zone.




For anyone who is interested...a quick video is posted here: http://www.youtube.com/watch?v=iAoDkzDBn2s

The video is pre-CIM. The shooter is just being driven off of our Dewalt cordless drill.

Hope it helps everyone get their shooters cranking!
-Brando

[MrForbes]

We put a bunch of arcs so we can slide a piece of lexan in and out (more compression and less compression) to tell us exactly what amount of compression worked the best. So far what we've seen is 7.5" to be the money zone.

That's what we found, although we didn't use such an elegant method to discover this fact :)


Hope it helps everyone get their shooters cranking!
-Brando

For all of us reading this...thanks!

[sdcantrell56]

Thanks for the informative post. I can't wait to see pictures of your prototype.

[Tom Line]

I am kind of surprised people are investing so much motor power in their shooters. 1 CIM seems like plenty of power to me.

Based off of our prototype shooter, 1 CIM spinning at 1:1 ratio with a 6 inch wheel threw the orbit ball ~30-35 feet, which seems to be awfully overkill for this game. This was feeding ball after ball right after another through the shooter wheel.

Brandon - the key isn't how far you can shoot - even a small motor can do that if you give it time to get up to speed. The key is how quickly the motor gets back up to your shooting speed. THAT is what will determine how quickly you can feed your balls to your shooter and remain accurate.

The less gear reduction you have on your spinner (and the less powerful a motor), the more it will slow and the longer it will take to get back up to speed. There are tricks to combat that - putting weights around the outside of your rim will act like a flywheel and decrease the slowdown you get from shooting (it will equally increase the time it takes to accelerate back up to speed).

Do some testing and see how much the shooter slows as you feed balls at a good rate (2-4 a second).

[Brandon Holley]

Brandon - the key isn't how far you can shoot - even a small motor can do that if you give it time to get up to speed. The key is how quickly the motor gets back up to your shooting speed. THAT is what will determine how quickly you can feed your balls to your shooter and remain accurate.

The less gear reduction you have on your spinner (and the less powerful a motor), the more it will slow and the longer it will take to get back up to speed. There are tricks to combat that - putting weights around the outside of your rim will act like a flywheel and decrease the slowdown you get from shooting (it will equally increase the time it takes to accelerate back up to speed).

Do some testing and see how much the shooter slows as you feed balls at a good rate (2-4 a second).

Tom,
I am aware of these facts. We are not planning on shooting the ball 30 feet in a match ( I dont believe any team is ). What I was attempting to indicate was that with 1 CIM we can throw a ball however many feet at 1:1, thus we could then reduce the speed from that data point.

We have stacked 3 balls directly on top of each other and fed them through the shooter so 3 balls in probably something like 1/2 second, only to see them all land in the same exact location.

I understand your concern from my comment, I am just trying to clarify to you that I am aware of the points you brought up. My surprise came from the fact teams were using 2 CIMs in 3 or 4:1 reduction setups....it seemed extraneous to me.

[Donut]

Tom,
I am aware of these facts. We are not planning on shooting the ball 30 feet in a match ( I dont believe any team is ). What I was attempting to indicate was that with 1 CIM we can throw a ball however many feet at 1:1, thus we could then reduce the speed from that data point.

We have stacked 3 balls directly on top of each other and fed them through the shooter so 3 balls in probably something like 1/2 second, only to see them all land in the same exact location.

I understand your concern from my comment, I am just trying to clarify to you that I am aware of the points you brought up. My surprise came from the fact teams were using 2 CIMs in 3 or 4:1 reduction setups....it seemed extraneous to me.

The reduction may just be for the effective flywheel radius; my team isn't using a wheel to shoot but we are running CIMs through the kit ratio toughboxes because our shooter has an effective "wheel" radius of 14".

As for using 2 CIMs it may be a little overkill, but we think it can't hurt, they're not needed anywhere else on our robot right now. I think it will help with our design though, the faster we can get up to speed (from a dead stop as well as after firing a ball), the better.

[Brandon Holley]

The reduction may just be for the effective flywheel radius; my team isn't using a wheel to shoot but we are running CIMs through the kit ratio toughboxes because our shooter has an effective "wheel" radius of 14".

As for using 2 CIMs it may be a little overkill, but we think it can't hurt, they're not needed anywhere else on our robot right now. I think it will help with our design though, the faster we can get up to speed (from a dead stop as well as after firing a ball), the better.

I absolutely think if you have them you should integrate them. I also don't know your exact design (but I have a good idea). With a radius of 14", it makes sense to use 2 CIMs IF you have them. Good luck!!

[pfreivald]

Tom,
I am aware of these facts. We are not planning on shooting the ball 30 feet in a match ( I dont believe any team is ).

The only reason to want to throw a ball -- accurately -- 30 feet is if you want to score all four of your empty cells into your two fueling stations in twelve seconds.

...but I only know of one team that's trying to do that. ;)

Patrick