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  #136   Spotlight this post!  
Unread 18-02-2013, 04:29
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Re: Prototype Small Wheeled Shooter

Quote:
Originally Posted by sdcantrell56 View Post
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.
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  #137   Spotlight this post!  
Unread 26-02-2013, 19:57
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Re: Prototype Small Wheeled Shooter

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!
  #138   Spotlight this post!  
Unread 26-02-2013, 20:03
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Re: Prototype Small Wheeled Shooter

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Originally Posted by rai337 View Post
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?
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  #139   Spotlight this post!  
Unread 27-02-2013, 06:48
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Re: Prototype Small Wheeled Shooter

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Originally Posted by CalTran View Post
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?fb...type=1&theater
  #140   Spotlight this post!  
Unread 27-02-2013, 09:24
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Re: Prototype Small Wheeled Shooter

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Originally Posted by rai337 View Post
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? Our team used a similar product back in 2010 for our ball magnet. Worked great.
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  #141   Spotlight this post!  
Unread 08-03-2013, 07:26
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Re: Prototype Small Wheeled Shooter

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.
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  #142   Spotlight this post!  
Unread 11-03-2013, 22:48
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Re: Prototype Small Wheeled Shooter

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!

Quote:
Originally Posted by TD78 View Post
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?
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  #143   Spotlight this post!  
Unread 12-03-2013, 08:50
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Re: Prototype Small Wheeled Shooter

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
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  #144   Spotlight this post!  
Unread 12-03-2013, 10:00
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Re: Prototype Small Wheeled Shooter

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.
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