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Subject: 
Re: Electric Compressor for Pneumatic Engines
Newsgroups: 
lugnet.technic
Date: 
Tue, 18 Jul 2006 17:09:07 GMT
Viewed: 
13202 times
  
In lugnet.technic, Mark Bellis wrote:
In lugnet.technic, Avi Parvin wrote:
I’ve build few type of pneumatic compressors with different motors and pumps,
and also few types of pneumatic engines. Unfortunately, none of the Lego
compressors were able to drive the engines more than one or two rounds. Manual
pumping proves that the engines are built correctly, but this is too exhausting…

Can someone please suggest a decent electric compressor, or at least compressor
spec (PSI), which is suitable for Lego? My requirements are simple: Strong
enough to drive pneumatic engine, gentle enough not to destroy the plastic
elements.

Thanks in advance,

Avi Parvin

I have a car tyre air compressor with a variable pressure limiter, which is
essential for LEGO pneumatics.  It will nominally produce 250psi.  I set the
limiter to 20-25psi normally, perhaps 30psi for short periods.  Note that you
need a pressure limiter, not a gauge.  The compressor with a pressure limiter
costs 4/3 as much as one without.  Mine was £19.99, probably $25-30. The
compressor is quite noisy and runs off 12-14V car battery voltage.  I use an
ex-computer cabinet power supply that provides 12V at 6 amps - the compressor
uses up to 4 Amps when driving LEGO models.

The compressor works well on my pick and place robot, which usually requires 6
hand pumps to operate.  I think the compressor provides about 8-10 hand pumps
worth of air at up to 30psi.  I used the football inflator attachment in the end
of a LEGO pneumatic tube, with a rubber band rolled over the two to stop the
tube detaching.

If your model won't move at 25psi then you need more cylinders in parallel.
This follows the principle of reducing the load on expensive LEGO parts in order
to maximise their life.  I always use 2 opposing cylinders for turning a
turntable.  If the load is more than 2 switches, use more cylinders.  In my pick
nad place robot, the greatest load is 2 cylinders pushing 5 switches, which
sticks a bit at 20psi, works OK at 25psi and is fast at 30psi.

Mark

Thank you very much for the detailed answer.

I’m starting with foot pump (5$), and will search for electric compressor later
on. Pressure limiter, as I understand, is a must. I also prefer 220V. With those
two constraints the offering is very limited, so it may take some time to find
the proper one.

Avi Parvin



Message is in Reply To:
  Re: Electric Compressor for Pneumatic Engines
 
(...) I have a car tyre air compressor with a variable pressure limiter, which is essential for LEGO pneumatics. It will nominally produce 250psi. I set the limiter to 20-25psi normally, perhaps 30psi for short periods. Note that you need a pressure (...) (18 years ago, 14-Jul-06, to lugnet.technic)

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