Vacuum

[nwagers]

Has anyone here created a vacuum with anything that has been given to us the past couple years? Just curious

[Stephanie]

uhm, have you?

[Jay05]

bump....

has anyone?

[KenWittlief]

I cant remember? does the compressor have an intake side that you can screw the filter off and put a fitting on?

if not, you can use the cylinders to create a vacuum - pulling the piston (with another piston) creates pressure on one side and vacuum on the other

just dont take it out into the woods, cause

nature abhors a vacuum!

[dez250]

i will try to post some photos, descriptions and white papers if i can of our vacuum design that we created and manufactured as a team for the Stack Attack competition robot, in the next few days. It was a great device, and most people who have seen it and know how it works are impressed by it. I know i personally am impressed each time its activated.
~Mike

[sanddrag]

I suppose someone could hack apart the compressor and turn it into a vacuum pump, or get or build a vacumm pump and drive it with a kit motor.

[IMDWalrus]

Originally posted by dez250
i will try to post some photos, descriptions and white papers if i can of our vacuum design that we created and manufactured as a team for the Stack Attack competition robot, in the next few days. It was a great device, and most people who have seen it and know how it works are impressed by it. I know i personally am impressed each time its activated.
~Mike

Definitely sounds cool, but I don't recall seeing your robot during the season. What exactly did you use the vacuum for? Stacking boxes? Moving them?

It's amazing what these robots can do...

[Erin Rapacki]

we made a very good vaccume without using the compressor last year... it's a cool idea

IM me, sn: errapi and i could attempt to describe it

[Justin Stiltner]

as of the 2003 season the only ways that you can create vacuum is to use a pneumatic cylinder or (i think) compress the air line. You could also get a suction cup that makes its own vac. when you say pull a handle.

The compressors don't have an vac. port on them and it is illegal to modify them to have one. Its also illegal to buy an vac. pump even if it is powered by an kit motor. However making one from a few small pneumatic cylinders and an kit motor is perfectly legal.. and has been done i think Erin's team did it but not sure

[Raven_Writer]

Originally posted by Justin Stiltner
as of the 2003 season the only ways that you can create vacuum is to use a pneumatic cylinder or (i think) compress the air line. You could also get a suction cup that makes its own vac. when you say pull a handle. ...

I know we made a vacuum last year using a pnumatic cylinder, couple other cylinders (I think), and used a pressure gauge to regulate it at 60 PSI.

I will probably be able to get more info. on this later on in the week.

[Jnadke]

Nobody has ever created a vacuum in FIRST robotics...

People have created partial vacuums, if that's what you mean.

There's a huge difference, a vacuum infers that there is no matter whatsoever inside the containment apparatus. With a partial vacuum there is air....
The difference is that with a vacuum the downward force exerted is 16PSI times the area of the suction cup.
With a partial vacuums, you have to use (16PSI - pressure inside) * area...
16PSI is standard atmospheric pressure.

There have been various attempts at partial vacuums... all methods employed suction-cup technology (as the rules state). Some just use regular suction cups, and press them to the surface, using force to remove the air and decrease the volume underneith the suction cup. Attempts to lift the suction cup then create an effective partial vacuum. At most, this system can only create equilibrium with the outside pressure. The partial vacuum is only created when you attempt to lift the suction cup.

Other attmpts include hooking the suction cup up to a cylinder, and then using another cylinder to increase the the total volume of the system, lowering the pressure. This, in effect, creates low pressure, and an overall downward force on the suction cup. This is much more effective than the first, because when you draw the cylinder, you create the partial vacuum. Any coefficient of friction between the surface and suction cup will be enhanced due to the downward pressure of the atmosphere.

My favorite, and probabaly the most effective, would be to use a one-way valve system and hook the suction cup to a cylinder. The air would be extracted from the suction cup (via equilibrium when you pull the piston), and then expelled out of another one-way valve. This would probabaly create the closest to a vacuum out of all three methods. I think I saw one team employing this method last year. I saw a motor driving a cylinder but I'm not sure if they were using a valve system (that would be pretty dumb if they weren't). As above, any COF would be enhanced.

[sanddrag]

Isn't there a way to connect a cylinder to a rotating cam powered by a motor and have that act as either a compressor or vacuum pump by use of a one way valve? I know I've done it with legos.

The problem is (for a compressor anyway) that the assembly must be very rigid because it will want to blow it's mounting points if it compressing the air is very difficult. Also, it will shake itseld very violently when the psi's start rising.

So do we even get one way valves? We have never used pneumatics so far so I am not too familiar.

[Jnadke]

Originally posted by sanddrag
Isn't there a way to connect a cylinder to a rotating cam powered by a motor and have that act as either a compressor or vacuum pump by use of a one way valve?

Originally posted by Jnadke
My favorite, and probabaly the most effective, would be to use a one-way valve system and hook the suction cup to a cylinder. The air would be extracted from the suction cup (via equilibrium when you pull the piston), and then expelled out of another one-way valve. This would probabaly create the closest to a vacuum out of all three methods. I think I saw one team employing this method last year. I saw a motor driving a cylinder but I'm not sure if they were using a valve system (that would be pretty dumb if they weren't). As above, any COF would be enhanced.

Although we don't get any valves that function with that respect in the kit, I'd imagine they exist. If not, then I'd be surprised. It'd probabaly be some sort of pressure valve. It could easily be created from some sort of rubber or silicone flap. When the pressure is greater the inlet side, the pressure forces the flap open and would equalize. When the pressure on the outlet side is greater, it would force the seal tighter.

There are pressure regulating valves at McMaster with a 0 PSI minimum differential, but I don't know if they are one-way... not to mention they cost $75 each...

[Justin Stiltner]

I think one team may have used the valves in the kit to accomplish this.. ie one opens, pulls air, then closes and another in the same line opens and the air is pushed out with the r/c controlling the opening and closing of the valves

[sanddrag]

You could have a switch located in a good spot on your vacuum pump assembly. When the cam rotates to a certain point the switch will be pressed. Then have the RC control a solenoid whenever the switch is pressed. Not too hard I suppose.