pic: Shooter damaged a Boulder

[falconmaster]

Originally Posted by MrForbes

Thanks for the report!

DITTO

[Josho499#4613]

Our team has found that the signature Vex "Colson Performa" (The smooth grey ones) wheels dont tear up the ball without sacrificing initial performance

[dkavanagh]

The boulders do compress and take some time to return to full size. Any thoughts on compressing in robot to make a smaller "object" to get into the tower opening?

[george.tan]

Originally Posted by dkavanagh

The boulders do compress and take some time to return to full size. Any thoughts on compressing in robot to make a smaller "object" to get into the tower opening?

I don't think you'll get much out of compressing the ball. Shooting a ball has been done year after year. I think teams has mastered the techniques of catapult and ball pitcher methods.

[XaulZan11]

Originally Posted by wilsonmw04

The ghosts of Rebound Rumble have returned...

Fingers cross they don't introduce brand new balls with different properties for the championship eliminations again...

[Ginger Power]

Originally Posted by dkavanagh

The boulders do compress and take some time to return to full size. Any thoughts on compressing in robot to make a smaller "object" to get into the tower opening?

I don't think this is something I would design my robot around. We're compressing the ball about 3" and it doesn't noticeably change the shape of the ball after it's out of the shooter. If you compress it any more you'll have to worry about things like stalling your shooting motors. Then you can try putting bigger wheels on the gain some linear speed while gearing down the motors. By then you'll notice the shooter is clunky and doesn't fit into tight places where you want it. Then you'll realize wow, this change is causing more trouble than it's worth. Smaller wheels, fine tuned compression, low gear ratios, and high rpm's. Those are the constraints I'd be designing my shooter around.

[jiggam]

I have managed to find to different places where you can get the balls from. Here are the links.
http://www.andymark.com/FRC16-p/am-3276.htm
http://www.gophersport.com/pe/premiu...oam-dodgeballs

Hope this helps.

[IronicDeadBird]

Originally Posted by MrForbes

After playing with the ball for a few minutes, I have very little interest in trying to shoot it using a spinning wheel. It's not that type of ball.

However, building a medieval siege engine (catapult) looks like a neat plan!

I have a feeling that this is what the GDC wanted you to feel. It was no coincidence that from the material down to the name of the game piece it automatically scream catapult.

[nxtmonkeys]

Well...
BALLISTA FOR THE WIN

Maybe.

Anyways, had to stop a rookie from picking at the skin of our boulder... It seems heavier than it looks.

[Chak]

Originally Posted by Anupam Goli

What tread were you using on the plaction wheels? I'd avoid roughtop and go for a smoother tread.

Originally Posted by SenorZ

Who'd have thought having a fast moving rough piece of plastic pressed up against a thin plastic coating on a foam ball would do damage?!?

Originally Posted by Josho499#4613

Our team has found that the signature Vex "Colson Performa" (The smooth grey ones) wheels dont tear up the ball without sacrificing initial performance

Originally Posted by jwfoss

We've run a ball through a shooter prototype around 10-15 times with no damage at a few different compression setting. I strongly suggest using a wheel with a smooth surface (Colson, Stealth, etc) if working on a flywheel type shooter.

Thanks for the suggestions! We were prototyping on the second day and grabbed whatever 6'' wheels we had on hand to throw something together . Now that we've seen what plaction wheels can do to our ball, I think we'd be using Vexpro colsons or one of Andymark's colored stealth wheels, depending on how they perform in a later prototype.

Originally Posted by Ether

May I ask: were you commanding full voltage to those miniCIMs, or some fraction thereof?

We were running the motors as hard as we could. I think we can safely assume that the motors were getting full voltage.

Originally Posted by philso

Are you gently pushing the ball towards the spinning wheels and allowing them to grab the ball or are you vigorously pushing the ball into the space between the spinning wheels?

I wasn't the one putting it in, from from my perspective, we were not vigorously pushing the ball in, nor were we especially gentle. We just put it forward and watched it shoot.
Is that a significant factor in damaging/shooting the Boulder? After all, the robot would be pushing the ball into the shooter with some amount of force anyhow.

Originally Posted by Ginger Power

The GreenHorns' wheeled shooter is at the point where we aren't tearing up the ball anymore (initial tests were brutal on that ball!) Thanks to Andymark for the donated game piece!!! Now that it's tuned we're throwing about 15-20 feet and it's very accurate. Our current game piece is beat to heck and the flight path hasn't changed since all the little nicks and cuts developed. We have a new ball and an old ball and they fly the same.

Don't be afraid of wheeled shooters this year. The 1114 style articulating arm is going to be gold this year (it is almost every year...).

Originally Posted by Ginger Power

Smaller wheels, fine tuned compression, low gear ratios, and high rpm's. Those are the constraints I'd be designing my shooter around.

Thanks for the advice! We were going to use smaller wheels, but we had a scrap piece of 2x1 handy to fit a 6'' wheel shooter. Can you describe your "fine tuned compression"? I've always assumed that moving the 2 flywheels on the same shaft closer together would be enough to vary compression. Is that true?
What is the 1114 style articulating arm? A quick google search yields this thread.

[Ether]

Originally Posted by Chak

We were running the motors as hard as we could. I think we can safely assume that the motors were getting full voltage.

http://www.chiefdelphi.com/forums/sh...14&postcount=7

[Ginger Power]

Originally Posted by Chak

Thanks for the advice! We were going to use smaller wheels, but we had a scrap piece of 2x1 handy to fit a 6'' wheel shooter. Can you describe your "fine tuned compression"? I've always assumed that moving the 2 flywheels on the same shaft closer together would be enough to vary compression. Is that true?
What is the 1114 style articulating arm? A quick google search yields this thread.

Fine tuned compression: The point where the wheels don't slip on the ball and it doesn't leave black streaks, but it isn't over compressed. It isn't an exact science (for Ri3D at least...), but we found a compression of 3 inches gave us the results we were looking for. I can't speak to moving the flywheels on the same shaft closer together and how that affects the compression. Making an easily adjustable prototype is the best way to determine this

Simbot SS, 1114's robot in 2008 inspired their 2014 Robot.

[The Doctor]

I'm more impressed that you actually have a shooter. Or maybe my team is just a bit slow off the mark.

[RoboChair]

Originally Posted by nxtmonkeys

Well...
BALLISTA FOR THE WIN

Maybe.

Anyways, had to stop a rookie from picking at the skin of our boulder... It seems heavier than it looks.

A Ballista is a type of catapult, along with the Onager and Trebuchet are the 3 major types of catapult.


The More You Know!
/wavehandfromlefttoright

[Anthony Galea]

Originally Posted by Ginger Power

It isn't an exact science (for Ri3D at least...), but we found a compression of 3 inches gave us the results we were looking for. I can't speak to moving the flywheels on the same shaft closer together and how that affects the compression. Making an easily adjustable prototype is the best way to determine this [/url]

Just want to comment on this, we also found that 3 inches of compression is ideal. This ball can really fly.