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Subject: 
Re: Lego pneumatic systems overview?
Newsgroups: 
lugnet.org.us.lugola, lugnet.technic
Date: 
Tue, 23 Sep 2003 17:39:54 GMT
Viewed: 
2268 times
  
In lugnet.org.us.lugola, Brian Reynolds wrote:
Hey there folks, recently my eyes were opened to the mechanical
possibilities that the Lego pneumatic systems allowed and today I
received my Bricklink order for a couple pumps, pistons, switches,
airtanks, and tubes and have been happily testing out the functions that
immediately pop into my head.  Since I don't have any previous
background with these tools though I'm curious if anyone out there can
give me a bit of a primer about what I can expect from these, so here's
a couple questions right off the bat:

1) How sturdy are these things?  The whole process revolves around air
pressure so I really want to get a sense of how much danger there is of
overpressure (specifically with the airtank), unreleased pressure over
time, and potential damage / wear and tear over time.

My friend Doug has used them up to 30 PSI.


2) How strong is the air pressure?  How much weight can a single
cylinder move at full pressure?

I don't know what the maximum allowable pressure is, but 30 PSI is probably a
good upper bound.

It depends on which direction you are trying to move the weight.

If you are trying to move it horizontally, then it depends on the friction
between the weight and the surface.  With zero friction it can move any weight.

If you are trying to move it vertically, then it depends on the pressure.
Pascal's law describes how these things are related.

Force = pressure x area.

You need to know the area of the piston head, and the pressure.  Small pistons
produce much smaller force than the larger pistons (using the same pressure)
because of the smaller piston/cylinder diameter.

I do not know the diameter of the pistons off the top of my head.


3) I have two cylinders
(http://www.bricklink.com/catalogItem.asp?P=2793c01) but one is brand
new while the other one is used and the used one takes longer to slide
in and out than the new one.  The used one has some sort of gunk on the
tube that appears to be causing extra friction where the new cylinder
doesn't.  Can this be cleaned off or is it just the product of age and
deterioration?

4) Is there a way to use the t-pieces
(http://www.bricklink.com/catalogItem.asp?P=4696b) as tubing extenders?
    I haven't seen anything that would act as a plug for the third
opening so that air doesn't leak out of the circuit in the process.

As pointed out by others, using the Flex system hose is better than using T's.
In fact over long hose lengths it is better to use mostly flex system hose and
use small pieces of pneumatic hose to connect them together.

Long pieces of pneumatic hose tend to act a little like balloons.


5) I'm not really big into the "Technic look" of Lego building although
I really appreciate learning from the visible enginuity that that
building technique shows off.  Can anyone recommend some particularly
good sites that show off more "beauty models" that also incorporate
pneumatics in them?

I don't know if you consider my stuff beautiful, but I have made a lot of
interesting things using pneumatics:

My first pneumatic biped:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=38069

My second pneumatic biped:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=46671

Two pneumatic adding machines:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=38075
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=38283

Some pneumatic creatures:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=38103
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=38496
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=48796

Some intro images:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=46353

Some basic computing circuits and pneumatic engines:
http://www.brickshelf.com/cgi-bin/gallery.cgi?f=44968


Thanks so much for your time!

-Brian Reynolds

Before you buy more pneumatics off bricklink, I'd recommend you consider buying
the 8455 Back-Hoe.  It has 10 large pistons, 2 large pumps, 7 switches,
pneumatic T's, and hose.

http://shop.lego.com/product.asp?prod_id=8455

If you have any questions, feel free to ask.  I'm quite intersted in pneumatic
designs, especially other people's work.

Kevin



Message has 3 Replies:
  Re: Lego pneumatic systems overview?
 
(...) What I'm currently thinking about is a mechanisim that will move an arm that's hinged at one end through a near 180 degree arc before it comes to a rest and then to have the reverse switch pull the arm back to it's initial position. At one end (...) (21 years ago, 25-Sep-03, to lugnet.technic)
  Re: Lego pneumatic systems overview?
 
(...) For models with a lot of cylinders I use a car tyre air compressor. I bought the slightly more expensive one tha has a variable pressure limiter and set the limiter to 20 PSI initially. This wasn't quite enough. 25 PSI was good for all but the (...) (21 years ago, 26-Sep-03, to lugnet.org.us.lugola, lugnet.technic)
  Re: Lego pneumatic systems overview?
 
(...) Don't know about 'beauty', but my dancing Easter chickens were popular at work: (URL) ran them off the compressed air coming out of the wall (in a hospital), and I had to turn the pressure way down to keep them from boucing apart... (18 years ago, 10-Jul-06, to lugnet.org.us.lugola, lugnet.technic)

Message is in Reply To:
  Lego pneumatic systems overview?
 
Hey there folks, recently my eyes were opened to the mechanical possibilities that the Lego pneumatic systems allowed and today I received my Bricklink order for a couple pumps, pistons, switches, airtanks, and tubes and have been happily testing (...) (21 years ago, 23-Sep-03, to lugnet.org.us.lugola, lugnet.technic)

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