Vacuums!
 

"For the purposes of the FIRST competition, a device that creates a vacuum is not considered to be a pneumatic device and is allowed. This includes, but is not limited to, Venturi-type vacuum generators and off-the-shelf vacuum devices (as long as they are powered by one of the Kit-of-Parts motors)."

I was curious, is this as easy as reversing the pump to suck? :yikes:

Re: Vacuums!
 

I was curious, is this as easy as reversing the pump to suck? :yikes:[/quote]

In my experience in custom airbrushing, due to the way the pumps move the air they dont create a substantial vacum on thier own. Idk about the first pumps but I know if i try using mine to suck it heats up fast.

Re: Vacuums!
 

In my experience in custom airbrushing, due to the way the pumps move the air they dont create a substantial vacum on thier own. Idk about the first pumps but I know if i try using mine to suck it heats up fast.[/quote]

I would NOT recommend hooking your pumps in reverse, due to the fact they were never built to work that way. (otherwise there would not need to be a resona to color-code the wires ;) )

Re: Vacuums!
 

If you look at the manufacturer's website, they say the the head is set up for compression only. Product Page

I would take this to mean that if you hooked something up to the suction side it would not create very much suction because the rubber piston seal would be useless.

Re: Vacuums!
 

Good idea! I wish i'd thought of it

Re: Vacuums!
 

The KOP compressor will not work as a vacuum pump, but it is not necessary when you have the KOP vacuum generator and suction cup. We tried picking up an inner tube with it, and it is more than enough to hold on to the tube.

Re: Vacuums!
 

the punp creates a lot of vaccum pretty fast as seen here:
http://www.frc-1947.com/Stuff/vacum1.avi
http://www.frc-1947.com/Stuff/vacum2.avi

Re: Vacuums!
 

Something we came up with, as an alternative (if we don't need the compressor onboard or just want to do something different) involved a piston, screw drive assembly, and a little motor.
The idea is that you rig up the end of the piston's rod to the nut of an acme thread (or KoP, whichever) screw drive and mount a small, fast motor to the screw. The piston is staged with the rod all the way in, with the nut at the extreme nearest point to the piston. Your vacuum line is connected to the piston at the opposite end from where the rod enters. The other end (nearest the rod) is left open to allow displaced air to escape.
When you want to produce a vacuum, all you need do is power that motor until it has driven/pulled the rod far enough to create the desired vacuum strength. You could reverse this idea and start with the piston all the way open and the vacuum line connected at the other fitting, then push the rod in until you have the desired strength. You also could push/pull the rod with a cable or lever or something else.
I think this is allowed, but I must admit that I haven't gotten too far in this year's manual yet.

Re: Vacuums!
 

[quote=Arkorobotics;549662]"(as long as they are powered by one of the Kit-of-Parts motors)."

QUOTE]

This is were the "got you" is. The air compressor is not a KOP motor. So, using it a vacuum device would not be allowed.

Re: Vacuums!
 

the compressor has a motor in it, and its in the kit of parts....

Re: Vacuums!
 

Hey does anyone know where we can buy extra suction cups? And the hardware for that.

Re: Vacuums!
 

We made a vacuum generator in 2004 using a globe with a crank on the end of it to drive a pnuematic piston with check valves on it. It worked well. This is the type of mechanism that the rule refers to not reversing or some other way tampering with the compressor.

Re: Vacuums!
 

Could you post a picture of you piston and valve idea or a larger description?

Re: Vacuums!
 

I don't have any pictures I can post. I'll see if I can get one at one of our meetings this week. As for a description, short of a P&I diagram of how to make the system work a picture is the only way to explain it so most people can understand what we did.

Re: Vacuums!
 

That is true. But, the Compressor comes under the rules R99 to R106. You will have to present a good case to convince me that the cmpressor can be use as vacuum device

Re: Vacuums!
 

One source is McMaster-Carr - search for "vacuum cups". They start on page 2602 about half-way down and there's a bunch more types on the next page.

Re: Vacuums!
 

Or try your local PIAB rep.
http://www.piab.com/Templates/FrontPage.aspx?id=5384

Re: Vacuums!
 

Hey guys,:yikes:
I'd appreciate if anyone posted here a picture of the vacuum cup, i'm from brazil, the kit didn't arrive here, yet.
anything will do,
thanks a lot=D

Re: Vacuums!
 

Try the manufacturer's web site, there's a list of them on the FIRST website.

The compressor itself, no, but using the air output to power a vacuum generator as supplied in the KOP works surprisingly well.

See the links in Post #7 of this thread, you can see it very well.

Don

Re: Vacuums!
 

Im just messin around, the compressor is not made to be a vaccuum, and there are plenty of other ways to make a very useful vaccuum if thats the route you look to take

Re: Vacuums!
 

Reversing the compressor is a bad idea. Especially when we have a venturi vacuum generator that works perfectly fine with compressed air. Plus the advantages of using the compressor are that multiple functions can be powered by the compressed air it generates.

There are other, non-pneumatic, ways of producing a vacuum. Driving a piston with a motor works, but relies on a good seal (you can only evacuate the length of the piston). Drawing a good seal is still important for continous vacuum device, such as the venturi or a KOP motor+impeller, but since these type are always drawing in air, loss of seal doesn't mean loss of object.

One other disadvantage (or advantage) of piston type suction devices are that once the seal is made, the amount of suction is determined by how far the piston rod moves. Since continous type are open to atmospheric pressure the vacuum is determined by other things like air flow rate and pressure or motor speed.

If you are using pneumatics this year, the venturi pump is great. If you not going with a pnuematics a KOP motor with an impeller (FP with an impeller from a small shop vaccum worked great in '04) will work and can fairly small and light (you only near the small motor, impeller (plastic), and a housing).

Re: Vacuums!
 

Not true. Just be more creative and you'll figure it out.

Re: Vacuums!
 

They (the copresssors) make the same air pressure when wired backwards, (don't argue), the problem is the cooling fan runs the wrong way and the compressor will overheat early.

Re: Vacuums!
 

I can think of being able to evacuate with a partial throw and continue to slightly move the piston as one way.

Another way is when the end of the stroke is reached, switch the vacuum side of the piston to atmospheric pressure (solenoid with other outlet blocked) and move piston to starting position, swithc to open to the suction device again and then continue to evacuate.

Or the third is to run two connected pistons driven by a crank shaft with switching between the two vacuum chambers via solenoid.

The third is the most complex and closest to a continous vacuum. The second you have to stop for a bit to move and the first you still are stuck at the end of the throw.

edit: actually a single piston would work for the third. Just use a solenoid to switch because either way you pull/push the piston you will get a vacuum. Still this isn't continous because of the stops at the ends of motion. Also without care the switching may introduce enough atmospheric air to break the seal.

Re: Vacuums!
 

I forgot to mention the obvious for this earlier the compressor uses check valves in the head so even if you run the motor backwards its still a positive displacement pump.

Re: Vacuums!
 

So, vaccums don't count as pnematics. That leads me to two questions. One, if you run pneumatic devices with a vaccum, will they just work in reverse?
Second, if they work, does that mean we can forgo the pneumatc rules and use whatever actuators we want?

Re: Vacuums!
 

So do any of you guys know if you are allowed to use bigger suction cups?

Re: Vacuums!
 

You can use bigger suction cups

http://www.chiefdelphi.com/forums/showpost.php?p=550013

Re: Vacuums!
 

Is there an image/scematic for the most basic vacuum system using solenoids and the air storage tanks?? can you please post a url to it or maybe email it to me?

Re: Vacuums!
 

Wait a sec... That won't work. There's simply no way to run the kit Vacuum Generator (VG) an entire round solely from tanked air.

Unless you are generating vacuum with a kit motor and a pump assembly, you'll need the compressor, just to operate the VG. The kit VG is a Venturi device. Think of a soda straw that you blow across, to raise the liquid in a drink cup. It works like that. So, the VG is going to require constant airflow running through it just to operate, whether or not you're holding ANYTHING. Without a compressor, you'd run out of tanked air in only a few seconds after the very first time you activated your vacuum generator!

The basic schematic for a compressor based system is shown in the 2007 Pneumatics Manual. (See the sticky link for it at the top of the Pneumatics Forum.)

That said... *IF* you can come up with a vacuum pump assembly that you can hack to be run by a kit motor, NOW you have something! :D Your simplest move would be to design a "reversable air pump", and directly connect it to your suction cup. Run it one way to stick, and reverse the motor to blow-off the ringer.

If that's not possible, you'll need to either vent the line between your motor based homebrew VG & suction cup with a valve of some kind (the kit valves won't work for this app - they require pilot air pressure to work at all), or else inject compressed air with a separate valve into the line. (The latter IS possible with kit valves, but the system is more complex than a venting solution, since you're right back to requiring stored air or a compressor, JUST to run the kit valves!)

Does this answer your question?

- Keith

Re: Vacuums!
 

Kit motors and scrounged shop vac parts or serch for two stage vacume motors from surplus places. Remove motor guts, attach pulley, belt and kit motor, gear for between 15k and 28k (hope to keep current under 46 amps). Built two models last year. Never used them in competion.
Biff

Re: Vacuums!
 

We have a compressor taht refills the tanks whenever one empties so in theory we should be able to run the VG with tanked air.

Re: Vacuums!
 

compressors are heavy and fittings are heavy
are you shure you are making the most wheight efficent decision?
wheight of part vs eficenty
a griper can be just as efficent

Re: Vacuums!
 

:confused: How do you connect the vacumm to the pnuematic parts and pump.????:confused:

Re: Vacuums!
 

Has anyone else found that the suction cups really suck?
all puns aside... our team experimented alot with them and found that they were far from perfect, not only do they add a lot of weight, they take time to connect to the tubes [for the suction to build up] and are fairly easily knocked off the robot.
im thinking of trying the piston method as suggested above, since thats weight efficient and would probably be fairly powerful.
but i think custom suction cups are the way to go

Re: Vacuums!
 

Note:

The rules state that you absolutely never can and/or should reverse polarity on the compressor. If you do that the FIRST Safety Nazis will make you change it. Just use the vacuum pumps in the Kit (you can order more w/ cups for about 30$ from PIAB.com)

Don't reverse polarity on commpresors!!!

GO 753

Re: Vacuums!
 

To add to that, OTHERS have already stated (I'm not trying it to verify!): IF you try reversing the compressor, due to the valving inside it is still a compressor! The thing you lose is COOLING. The fan is not blowing air properly across the fins anymore. The compressor overheats, and given enough time it potentially become damaged, or destroyed.

So again, do NOT try reversing the compressor!

(I'm not sure about that one team's claim of being able to use the compressor as a vacuum pump. I'm curious how they actually did that.)

- Keith McClary
Chief Engineer, Team 1502, "Technical Difficulties"