Prototype Small Wheeled Shooter

[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

[Robo Hamsters]

Originally Posted by G Fawkes

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]

Originally Posted by 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!

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=zggvD...ature=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]

Originally Posted by 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.

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]

Originally Posted by 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

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. Neither the sponsoring teacher nor any of the mentors went for that idea.

[AllenGregoryIV]

Originally Posted by 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. 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.