1726 Prototype Testing
 

Here's a short video of our prototype mechanisms in use.

http://www.youtube.com/watch?v=LDvo2uY7dcU

You can also see some picture going up at:

http://photos.project1726.org

Comments, questions, suggestions appreciated!

Re: 1726 Prototype Testing
 

very nice, it goes up really high

Re: 1726 Prototype Testing
 

It goes a little higher when you hold it down (like it will once the last component is finished)

http://www.youtube.com/watch?v=G9y-LhHRAHw

Re: 1726 Prototype Testing
 

oh man that catapult is BEAST
what did you use to power the catapult?

I cant really tell, but is ure robot within the 28 by 38 requirement ?

Re: 1726 Prototype Testing
 

Best one I have see so far! That's great!

Re: 1726 Prototype Testing
 

I wasn't working on that component, but I think we have 2 2" bore 10" stroke pneumatic pistons. We did a 'trick' (well known, I think) by keeping the cylinder from moving at 60psi with 3in. filled. Then we release the ball, and the air stored in the 1/3rd of the cylinder expands very quickly, giving us enough force to launch the ball.

Right now we're working on lowering the air consumption (right now a single shot drops our pressure from 115psi to about 80psi...)

And yes, I believe it is within the limits... However, this is a culmination of 2 prototypes, a mechanism mounting bracket, and last year's robot. The real thing will (hopefully) be much nicer

Re: 1726 Prototype Testing
 

what do you mean by keeping the cylinder from moving at 60 psi with 3 in filled?

sorry Im a nub

Re: 1726 Prototype Testing
 

basically when the catapult is fully retracted, the cylinder sticks out 3 in. Before we shoot, we hold down the ball (from the top, we still have to make that part) and open the valve. Air from the tanks fills up that 3in. and we wait until it is time to fire. When we fire, we remove the top piece and the air inside the cylinders expands rapidly, launching the ball.

Maybe I should make a quick diagram...

Re: 1726 Prototype Testing
 

so your bore starts 3 inches, and it fires out to 10? so basically you're using the potential energy of the bore that is protruding 3 inches?
yeah a diagram might help...

Re: 1726 Prototype Testing
 

Think of it like a spring, but instead of energy being stored in the coils, its stored in the cylinder with the air. Only reason that it sticks out 3in is so the pressure can build, storing the energy.

Re: 1726 Prototype Testing
 

Exactly!

Here's a diagram (out of proportion and not quite right, but what the hay):

Re: 1726 Prototype Testing
 

Oh that is pretty cool
do u have to program the bore to protrude 3 " out, or do u mechanically set block it from full retracting (Im guessing the 2nd...programming a bore doesnt seem probable)
haha

Re: 1726 Prototype Testing
 

Are you at all worried about running out of air?

I think you might hurdle too fast (:D ) and drain your tanks.

Re: 1726 Prototype Testing
 

actually, yes, we are very worried about running out of air! Right now we lose about 35-40psi per shot, and it takes ~25-30 seconds to reload... Of course, you don't have to shoot it at 115psi, but we still plan on exploring different ways to conserve air.

Re: 1726 Prototype Testing
 

Well, you could start by removing all the other pistons.

Use servos to shift, and a motor to lift the loading forks. Pressurizing your tanks before every match might help maximize your air.