31-01-2009 23:34

Kyle Love

Re: pic: Custom Wheels

Nice shooter wheels.

31-01-2009 23:35

RyanN

Re: pic: Custom Wheels

What do I think?

Umm... bad year to decide to make your own wheels...

Oops.... You mean 'those' wheels. They look aluminumy... Someone spent a lot of time either making those or watching them be made assuming you did it on a lathe.

01-02-2009 00:26

Woodworker88

Re: pic: Custom Wheels

Those toolpaths look like it was done on a CNC mill or rotary table. Nice work, you guys.

01-02-2009 00:37

=Martin=Taylor=

Re: pic: Custom Wheels

Our team doesn't have the milling abilities to do these, so we had a sponsor mill them out. Then our students finished them up on the lathe.

They are by far the most complex/coolest looking parts we’ve ever made!

To give you some proportions they are 6" OD.

They are actually fly-wheels/roller-hubs. Hopefully they'll allow us to fire vast quantities of balls very quickly without losing speed and range.

01-02-2009 01:37

R.C.

Re: pic: Custom Wheels

And i thought your guys 07 arm was a beast. I can't wait to see that crazy shooter. Have a great build season and see you at DAVIS.

01-02-2009 11:53

amariealbrecht

Re: pic: Custom Wheels

wow your shooter is going to be great! I hope everything continues to go well for you this year and good luck at all your competitions!

01-02-2009 12:27

MrForbes

Re: pic: Custom Wheels

We have a very low inertia shooter driven by one CIM with about 1.5 reduction, and we don't have any trouble with shooter speed dropping when it shoots out 5 balls in rapid succession on full speed. We do notice that the motor slows down a bit when we have the speed reduced for shorter range, but I think if we get a speed sensor on the shooter wheel and set up a feedback loop to keep speed constant, it will be fine.

Very nice shooter wheels! what's the weight?

01-02-2009 23:41

=Martin=Taylor=

Re: pic: Custom Wheels

You appear to have misunderstood me when I said "vast quantities of balls very quickly." Think 10 balls in a fraction of a second

We actually modeled our shooter using rotational momentum, and imagined that the balls being fired were "collisions" slowing the wheel down. Adding the flywheels greatly improved consistency. Recharge went from about 1 second down to like .2 seconds. Of course we'll have to see about my math

They weigh 2.5 lbs. each. We know how much the final bot will weigh from CAD and this is a perfectly acceptable amount for us.

01-02-2009 23:50

MrForbes

Re: pic: Custom Wheels

Sounds neat! We have trouble getting more than 5 balls per second into the shooter....shooter speed is not the limiting factor

I wonder if there's going to be a fps limit this year like in 2006?

02-02-2009 00:22

Andy L

Re: pic: Custom Wheels

You have managed to scare me... What's your range like?

02-02-2009 00:29

=Martin=Taylor=

Re: pic: Custom Wheels

It was calculated at around 6'. We'll have to wait a few days to see for sure.

6' is more for awesomeness. I doubt we'd risk such a long shot in a match. 2-4' is more reasonable.

02-02-2009 00:31

MrForbes

Re: pic: Custom Wheels

Have you dont any prototyping with a flywheel shooter?

02-02-2009 00:33

Andy L

Re: pic: Custom Wheels

Wow, someone that thinks the same as our team. I see all these shooters shooting across shops for some reason, well I hope I get to see it in action at SV and Davis(are you guys at Davis this year?) on our side of the field preferably.

02-02-2009 06:52

GaryVoshol

Re: pic: Custom Wheels

Hush! Don't give "them" any ideas.

02-02-2009 08:56

XXShadowXX

Re: pic: Custom Wheels

how well do they grip the balls, thats one issue I've foreseen, is that your flywheels won't impart enough momentum on the balls in the time that they are in contact, do you plan to say wrap them in Velcro?

02-02-2009 09:06

MrForbes

Re: pic: Custom Wheels

gum roughtop tread works really well, there are other materials also that can grip the balls well. Velcro affects the fabric on the balls, so it's probably not the way to go.

02-02-2009 10:40

=Martin=Taylor=

Re: pic: Custom Wheels

They're never going to touch the balls.

We'll use wedge-top or neoprene rubber for traction on the roller surface.

02-02-2009 11:07

RogerR

Re: pic: Custom Wheels

I'm curious about your set-up; are you using some sort of clutch system to link these to your 'shooter'? traditional wisdom says that by adding rotating mass, you increase spun-up time (I assume this is what you mean by 'recharge'), though I doubt that an orbit ball would significantly effect the RPMs of these beasts.

Ironically, one of my teams went the exact opposite direction, minimizing roller mass, and instead using the shooting motors themselves to give a high rate of fire.

02-02-2009 12:19

=Martin=Taylor=

Re: pic: Custom Wheels

Yes that is correct.

Spin up time will be reduced, but less speed will be lost per shot, so it will be easier to maintain speed.

By constantly spinning the drum slowly we can ramp it up to firing power quickly whenever the need arises.

It is useful to reduce mass from the center of the rotating object, since this mass will not be spinning as fast as that on the edges. This is why we milled out the center. All the mass is on the periphery.

We actually built a very similar dual-ball shooter in '06 that suffered a great deal from recharge. Sitting on top of the ramp, it could only get the first two balls in before it lost speed.