Build Blitz Robot Reveal - Team JVN

[cbale2000]

What did team JVN use for surgical tubing on the launcher (and where do you get it)? The tubing we've been prototyping with has been less than effective.

[Aren_Hill]

Originally Posted by cbale2000

What did team JVN use for surgical tubing on the launcher (and where do you get it)? The tubing we've been prototyping with has been less than effective.

Just black Latex tubing from McMaster.
http://www.mcmaster.com/#latex-tubing/=q9fexw

I think that stuff was 5234K46 (1/2" OD, 1/4" ID)

[Ryan Dognaux]

I don't remember seeing this anywhere so I figured I'd ask - what material are the ball holding posts made from and is there a vendor where we could pick up a few?

[Aren_Hill]

Originally Posted by Ryan Dognaux

I don't remember seeing this anywhere so I figured I'd ask - what material are the ball holding posts made from and is there a vendor where we could pick up a few?

Ryan,

Those are chunks of McMaster part# 87235K81
We just shoved it over some standoffs made from 1/2" HEX stock.

-Aren

[KevinG]

What material did you use for those flexible black rods?

[Aren_Hill]

Originally Posted by KGenson

What material did you use for those flexible black rods?

1/2" Black Delrin rod, but many things will work, we just happened to have it on hand.

[Dan Oelke]

I love the choo choo. What I don't understand is how you did the pivoting joint between the parts of the linkage. Guessing from the video looks like about 1/4" x 1/2" bar stock and I just don't see how you can do a pivoting link in that 1/4" thickness.

Can you give me any pointers or diagrams or ?? about how that joint is put together.

Thanks!

[Aren_Hill]

Originally Posted by Dan Oelke

I love the choo choo. What I don't understand is how you did the pivoting joint between the parts of the linkage. Guessing from the video looks like about 1/4" x 1/2" bar stock and I just don't see how you can do a pivoting link in that 1/4" thickness.

Can you give me any pointers or diagrams or ?? about how that joint is put together.

Thanks!

In our case I essentially made a shoulder bolt that tightened into the first strap and captured a bushing which the other strap spun on, I "handcrafted" the attachments due to limited time and not having shoulder bolts of the proper size on hand.

[andboyer]

Can someone add a little more detail? The video doesn't explain the details of the release.

[Ether]

Originally Posted by andboyer

Can someone add a little more detail? The video doesn't explain the details of the release.

Look more closely at the bar link that's attached to the cam.

Notice how the protrusion on the cam catches that bar as the catapult is being pulled back.

Notice how, in the video, the cam stops before that bar goes over-center.

To release, the cam is rotated further (in the same direction it was turning before) until the bar goes over-center. At that point, the tension pulls the bar off the protrusion and launches the catapult.

[Willyspu]

On the opposite side of the 84t gear there is a pointer and switch, is this a encoder to hold the motor in the ready position? If not, what is it's purpose?

Thanks,
Jim
Team 2144

[Aren_Hill]

Originally Posted by Willyspu

On the opposite side of the 84t gear there is a pointer and switch, is this a encoder to hold the motor in the ready position? If not, what is it's purpose?

Thanks,
Jim
Team 2144

This single switch controls the entire retract and fire mechanism, since the cho cho only rotates once per cycle it is just as easy as running till the switch is hit, then stopping.
When the fire button is pressed the shooter pulses forward for .25 seconds, waits .25 seconds for the action to cease, then runs until the switch is hit again.

I have yet to see a simpler method.

[Willyspu]

What type of switch is this? Is it an on/off, position switch or encoder?

I am a mentor and just trying to figure out how you held the motor in position until you were ready to fire the next shot.

Thanks!

Jim
Team 2144

[Thad House]

Originally Posted by Willyspu

What type of switch is this? Is it an on/off, position switch or encoder?

I am a mentor and just trying to figure out how you held the motor in position until you were ready to fire the next shot.

Thanks!

Jim
Team 2144

The switch is just a limit switch that tells the system when to stop turning the motor. What actually stops the axle from backdriving is the wrench in that picture. It is just a standard ratcheting wrench, and you can see it in the picture right below the pointer.

[thesuperfez]

I have a question about the piston used to extend the rolling arm that collects the ball. We are a rookie team and are unsure of the sizing of pistons. Does anyone know the bore size and stroke length used for this bot in particular?