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Subject: 
Re: Lego pneumatic systems overview?
Newsgroups: 
lugnet.technic
Date: 
Thu, 25 Sep 2003 10:44:19 GMT
Viewed: 
2019 times
  
Kevin L. Clague wrote:

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...

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 of the arm will be a fairly sizeable
weight of bricks and plates.  So my current musing is how to make the
relatively short reach of the extended cylinder move the whole assembly
through that range of motion and then to build the arm base structure
and focal point strong enough that the whole thing doesn't come apart
under the lopsided weight change.

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.

Ouch!  Good tip!

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

Well, by "beauty" I mean that the focus of the model is an appreciation
of the aesthetic surface design and not the visible mechanical ingenuity
that makes everything work. I think a better term for the works you just
pointed to would be a hushed uttering of "technical marvel".  That's
REALLY impressive work and my mind bends trying to follow all the
construction gymnastics required to keep all that motion balanced and
focused.  That inchworm mpg file is downright creepy with the
bio-mechanical wave-like motion!  I'll assume that you must have had a
motor running a constant pressure-pump generator in order to get all
those cylinders working simultaneously?


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

Now that's something I didn't think of!  One of the Lugola members even
had a copy of this model at our meeting earlier this month (which
provided the first inspiration for working with pneumatics in the first
place) but I didn't stop to think just how many pumps and cylinders were
contained within the model.  Certainly for the price that those things
are selling for on Bricklink a quick acquisition of this much pneumatic
tools in one set is nothing to sneeze at.  Thanks for bringing that up!

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

Will do, though my own ambitions fall quite a bit shorter than the
amazingly intricate works you've assembled.  I'll do my best to make
something worthy of inspiration!

-Brian Reynolds



Message has 2 Replies:
  Re: Lego pneumatic systems overview?
 
(...) Near 180 degrees maybe tough. You'll need to keep the piston attached as close as possible to the pivot point of the arm to get the maximum range. <snip> (...) Thanks for the positive feedback. I have three large pumps all attached to the same (...) (21 years ago, 25-Sep-03, to lugnet.technic)
  Re: Lego pneumatic systems overview?
 
(...) Levers are your friend! Have a look at the mechanisms used to drive the buckets on 8455 backhoe (front and back), and similar models. While these operate nowhere near 180 deg, adjustment of lengths/fulcrums may well get you closer. ROSCO (21 years ago, 25-Sep-03, to lugnet.technic)

Message is in Reply To:
  Re: Lego pneumatic systems overview?
 
(...) My friend Doug has used them up to 30 PSI. (...) 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 (...) (21 years ago, 23-Sep-03, to lugnet.org.us.lugola, lugnet.technic)

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