Dual-flywheel BBMG

[D-Roc]

I'm going to build a new type of BBMG rather than the vortex or cloud design. It's going to be powered by two wheels that spin at a fast rate and the BBs just pass through it. I need any suggestions on what I should use for the wheels, motors, and batteries.

And if the wheels were spinning at 10,000RPM and a BB was coming through it at at like 3-5FPS (they're just rolling down from a magazine), what would the FPS be of the BB when it exits?

[Mihlrad]

no way in hell are you gonna get 10000 rpms... but i would use a pully wheel and glue small paddles to it to grab the bbs.

[D-Roc]

Well I was looking in to this...

www.powerballs.com

And you can get over 10k RPM just by shaking it. I plan to copy the style of the gyroscope and power them by some good motors.

[carlbelcher]

Those gyroscope balls are pretty hare to use. But you can easily get well over 10K up to 30K rpms with a R/C airplane motor.



Tower Hobbies

[saladtossser]

r u talking about a centrifigal bbmg?
nvm i see

[Torch]

Hmmm....I wonder if some old harddrives would work for this. Im not sure how you would power them and such though.

[Brian the brain]

Use an angle grinder to spin the wheels.Use relatively large and heavy wheels, they will have the momentum to keep running at high speeds.Use wheels with rubber tires for a good grip.

[carlbelcher]

I don't like the idea of using an angle grinder for three reasons.

1. They’re too large and heavy
2. They’re AC powered (Not Portable)
3. They’re Expensive

I would go with an r/c type motor: they’re small, powerful, and battery powered. You don't really need too much momentum or with as much power as a grinder, we’re only talking about bbs here. An r/c car or plane motor will give you plenty of power. They're also quite small and battery powered so they're very portable. You also get much higher rotational speed (up to 40,000 rpms) which in this case is the most important factor, the higher the rotational speed the faster the bbs are going to fly. And best of all r/c motors can cost as little as $3-$5.

[Benny]

http://www.geocities.com.nyud.net:8090/pest3125/
The P.E.S.T
Exactly what your describing, too bad the projectile is ony as fast as the wheels.

[D-Roc]

I don't like the idea of using an angle grinder for three reasons.

1. They’re too large and heavy
2. They’re AC powered (Not Portable)
3. They’re Expensive

I would go with an r/c type motor: they’re small, powerful, and battery powered. You don't really need too much momentum or with as much power as a grinder, we’re only talking about bbs here. An r/c car or plane motor will give you plenty of power. They're also quite small and battery powered so they're very portable. You also get much higher rotational speed (up to 40,000 rpms) which in this case is the most important factor, the higher the rotational speed the faster the bbs are going to fly. And best of all r/c motors can cost as little as $3-$5.

WTF? I can get r/c motors for $5? Where?!?

[carlbelcher]

Here is one on eBay for $.99 but its $12.00 for shipping
Ebay Listing

And here is a less powerful one for $3.99
Surplus Center Item

And here is another one for only $1.95 for 4
Edmund Scientific Item

Granted if you want a super-powerful motor you're going to pay more money.

[D-Roc]

Can I just by those small cheap motors and power them by a series of 9volt batteries? Will the RPM increase with more battery volts?

[carlbelcher]

The rpms will increase with voltage, but overvolting will eventually destroy the motors. If you really want super high rpms (20K - 40K rpms) I would spend a little more on a brush-less motor. The only problem is brush-less motors require a special speed controller that can be expensive.

[pyromanic13]

isent the military looking in into centrifical turrets? check howstuffworks.com I think I saw it on there.

[benstern]

http://www.onlineconversion.com/wheel_surface_speed.htm