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 Robotics / 10505
10504  |  10506
Subject: 
Re: Pneumatic Solenoid Valve Interest Poll
Newsgroups: 
lugnet.robotics
Date: 
Sat, 5 Feb 2000 03:14:05 GMT
Viewed: 
1747 times
  
Just as a follow-up and to answer some questions that I have received via e-
mail.

Re: 2-way or 3-way valve
These solenoid valves are three way, meaning they have a port for IN, OUT and
exhaust.  When not powered the IN port is closed to prevent leakage from your
source (tank) and the OUT is vented to exhaust to allow your cylinder to
depressurize.  When powered the exhaust port is closed and the IN ports to the
OUT to pressurize the cylinder.  So its not a straight 2 way valve where the
pressure in the cylinder can never be released.

Re: where did you get these so I can go there too and buy some myself?
I have searched high and low for similar solenoids, and have not been able to
come up with anything in a reasonable price range.  To be honest, the next
higher priced usable solenoid I could find was more than 5 times the price I
paid for these.

Re:  what do you mean by 85%?
I was not clear at all when I made this statement.  I bought a big pile of
solenoids, and found out that some of then will not actuate consistently with
the 8 volts from the RCX.  These I put in a separate pile and have not been
doing much with.  The rest I tested to make sure the held air and actuated.  I
hand tested all of them with a hand pump and a blue air tank and tested at
which pressure they would start to leak.  They were originally manufactured to
handle 20-25psi.  I found that all of them began to leak at about 20 or 25
full strokes on the hand pump.  I do not have a way of actually measuring the
PSI, so from now on everything will be calculated in terms of pumps.  I then
tested to make sure all of them actuated correctly and ported to the OUT
without leaking.  All tested successfully at the RCX voltage of 8 volts.
However, while working with an actual model (that should appear in an AVI very
shortly) I discovered to my surprise that one of the solenoids occasionally
leaked to exhaust rather than porting to the OUT.  It did it a total of 3
times over 20 trials, hence my 85% number.  Since then, however, I have not
been able to get it to reproduce the problem.

While working with a cylinder from the discard pile I encountered a similar
problem.  This cylinder would consistently leak to exhaust and not port to
OUT.  I disassembled the valve, cleaned it and weakened the spring slightly,
and since then it has performed at 100% as well.   Therefore, the 85% number
is not accurate.  I have been able to get all of the cylinders to perform
consistently with a bit of minor work.  All the cylinders that did not trip at
8 volts are not included so no one will get stuck with one.

Re: yes, Id like these, how much do you want?
Originally I had posted to the newsgroup to get a feel for how much people
were willing to pay.  Interestingly enough not a single person responded with
an actual number.  So Ill go about it another way.  I have been able to
improve the reliability of the Solenoids to provide consistent performance
(subject to occasional tweaking).  I am going to keep a few for myself, which
means I have 20 or so available for sale.  Given my materials costs (which Id
like to recover) I can sell them for $35 each. First come first served.
E-mail me for orders and questions.  I will be posting an ad on the Lugnet
shopping channel which contains additional specs and information on the
solenoids.

Thanks for your interest and help, I only have 20, so e-mail me quick.  Thanks.



Message is in Reply To:
  Pneumatic Solenoid Valve Interest Poll
 
I managed to find a small collection of 12V Solenoid valves. I have been working on trying to get them to work with the RCX Brick. The voltage output of the Brick is pretty low. I have been able to get very good success using just a battery pack and (...) (24 years ago, 4-Feb-00, to lugnet.robotics)

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