Can you create vacuum using pneumatics ?

[TechnicFan68]

I'm trying to create at device which will retrieve one sheet of paper strip from a large stack. After several unsuccessful attempts (lots of paper jams), I've decided to try using vacuum to suck up the top sheet and transfer it.

But I'm not sure how I can create vacuum using Lego Pneumatics?

I found this project on Lego Mindstorms pages Vertigo III, but it mentions a one-way valve that seems very diffcult to obtain...

I only have second generation pneumatics, but I can buy the first generation pneumatic block Bricklink pneumatic block if that helps.

Thank you for any help.

Arild

[efferman]

theoretical you produce a vacuum at the lower cylinder air intake when you pull the pistonrod out of the cylinder. maybe you could this use it with a hose and a dish to create your paper sucker

[TechnicFan68]

theoretical you produce a vacuum at the lower cylinder air intake when you pull the pistonrod out of the cylinder. maybe you could this use it with a hose and a dish to create your paper sucker

I tried that already, but a single stroke from a cylinder does not provide enough vacuum to hold onto the paper :-(

Granted the seal between the dish and the paper wasn't very good, but I think I need more...

Arild

[blueShinyApple]

use the old distribution block, made for creating vacuum

edit: didn't see you wrote that awready.. but thats the easiest way.

Edited February 12, 2011 by blueShinyApple

[allanp]

Would I be right in saying it's for a printing machine? Like a heidelburg?

If so then I would stick with the valve block. You should in theory be able to use an airtank to "store" some vacuum. So you can be generating the vacuum all the time and switch a valve using a cam to give you instanct vacuum. Then maybe you can get 180 sheets per minute

However you could always try efferman's idea again but using more than one cylinder. But I would think one is enough providing you have a good enough seal. What dish piece did you use?

Edited February 13, 2011 by allanp

[Dutch_EE]

If we only had one-way valves.

[Zerobricks]

If we only had one-way valves.

Old distribution block is a one way valve!

[TechnicFan68]

Would I be right in saying it's for a printing machine? Like a heidelburg?

If so then I would stick with the valve block. You should in theory be able to use an airtank to "store" some vacuum. So you can be generating the vacuum all the time and switch a valve using a cam to give you instanct vacuum. Then maybe you can get 180 sheets per minute

However you could always try efferman's idea again but using more than one cylinder. But I would think one is enough providing you have a good enough seal. What dish piece did you use?

I used a 2x2 Inverted Radar disk BL link which I found to be pretty useless in this context. I have both the 3x3 (BL 3x3 Radar Dish) and the Scala 5x5 dish (BL Scala 5x5 dish) on order. Hopefully one of them will yield a better result. I'm also thinking about putting some silicone around the edge, or gluing on a pulley tire BL Pulley Wheel Tire.

As for the usage - it's not a printing device. It's purpose is to load these target strips Image of target strips in front of a pellet catcher, so I can continue my training during my summer holidays.

[Lasse D]

How about using those pumps that go with the racer cars where you step on the things to make the cars go?

Block the intakes and create a much larger suction than using pneumatics.

[vmln8r]

Would I be right to say that only the old-style pumps () will work to create a vacuum using the distribution block ()?

[Blakbird]

Not exactly. The old pump doesn't have a check valve so it creates suction whenever it is lifted. If you were to push it down and then connect it to something, it would suck the air out. If you want to be able to pump repeatedly, then you need to use the check valve built into the distribution block. So it is possible to do it without the block, but much easier with it. Of course, you will never be able to create a complete vacuum, but you should get close.

[vmln8r]

Ah, thanks. I have the new pumps, which I assume have check valves? When I connect a pump to the central port on the distribution block, and a new cylinder to each of the output ports (via the cylinder's lower port), pumping simply extends both cylinders. I had assumed (from here) that on the distribution block:

The leftmost port could only have air going into it, no air would ever come out. The middle port could have air going in or out. The right port could only have air coming out of it, no air could go into it.

How then should the distribution block be connected, such that continuous pumping will provide a continuous vacuum?

Edited June 25, 2013 by VMLN8R

[martinnygaard]

I've build a vacuumpump some time age. A engine with a crankshaft is turning regular 2-way cylinders and valves at the same time (opposite LPE)

If the motor runs one way it create pressure - opposite vacuum ;-)

[Blakbird]

How then should the distribution block be connected, such that continuous pumping will provide a continuous vacuum?

You've probably connected it right, but you'll have to use the old pumps. The new pumps will never create any suction at the port. They are specifically designed not to.