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Here is a photo of the compact
regulator I use on all of my
animatronics that you might want to
consider adding to your air trigger
assembly as well. It is a Harbor
Freight item
no#
90590-0VGA 1/4" Air Regulator With
Gauge and is NOT to be
confused with an Air PRESSURE
regulator sold for a few dollars
less at the same store. The
diaphragm regulator works like the
unit on your air compressor,
releasing a total air pressure as
shown on the gauge and never more
than that. An air pressure
regulator is a FLOW regulator only.
Meaning that if you have a flow
regulator adjusted to 28 lbs and
are sending 105 lbs of pressure
going into the intake AND keep the
air flowing through constantly, the
pressure coming out will stay at 28
pounds. But once you stop this
flow, the pressure that backs up
against its inner mechanism allows
the full blast of pressure you have
going in to be emitted initially,
until the flow stabilizes. Thus, if
you have an animatronic that works
on 28 lbs of pressure such as the
Exorcist, a PRESSURE regulator,
if left hooked up to 105 lbs of
direct pressure from the air
compressor but set to 28 lbs for
your prop, will send your puppet
through it's cycle about 4 times as
fast as needed and probably through
the ceiling. Funny as hell for a
just a moment until you realize you
have to replace all its working
mechanism and patch that hole in
your garage roof. So be sure you
are buying a DIAPHRAGM regulator. I
am asked all the time how to hook
this up to your 1/4" IID air
fittings and the answer is exactly
like regular fittings. Even though
these look a little different, they
do seal off just fine when using
Teflon tape.
For years I have heard the loud
hiss as the bypassing air escaped
out while my props were triggered
and then the long hiss while it
reset back to its ready position.
This year I determined that I would
make a silencer for this sound.
Here you will see one very easy way
to accomplish just that, however
you will find another, newer
version at the bottom of this
how-to that is more compact and
will work with smaller air line and
can even be fitted for use with a 2
way air cylinder that requires both
inlets to be silenced while in use.
I found that 3/4" PVC pipe has just
a little larger diameter inside
than the 3/8" air hose I work with
has for an outside diameter so it
made sense to start there.
I had an extra foam paint brush
laying around so I cut a couple of
strips off that would slip inside
the 5" section of pipe. Then using
a jig saw I slotted up one end of
the pipe in about 4 places and
simply hosed clamped that end to
the air line. To hold the foam in
place I put a screw in
the other end. This is a really
solid mount to the heavy rubber air
hose, so it will not be falling
off. Now When I set up my props I
simply run the muffler line out
behind the prop behind the wall to
hide it. The sound is not only
eliminated nearly 100%, but by
introducing the muffler to the
system actually cuts down on the
air pressure needed to activate the
prop and in turn less air volume.
And that means less refilling of
the compressor tank during the
night.
NEW! The new "compact"
muffler shown here uses 1" PVC pipe
just 2 1/2" long with one end
capped and threaded for the valve
you see installed. The hose fitting
in the other end of the valve
(which allows you to choose exactly
how fast or slow you want your prop
to reset) is a 1/4" slip fitting
that is the right size for 3/16"
O.D. clear vinyl hose. The muffler
is then stuffed fairly tight with
foam rubber and then screws are
installed at the end to keep the
foam from coming back out. This
super compact muffler makes all
exhaust from the cylinder completely
silent, making it both effective as
well as extremely easy to fit
inside of any pneumatic prop.
In the far right CAD drawing you
can see a very simple way to cut
the threads into your end cap. Once
you drill out a hole just under the
diameter of the threads of your
fitting (15/32nds drill bit), you
can use the fitting itself as a
thread tap by cutting across the
bottom few threads with the sharp
corner of a metal file. The more
vertical the cut is on the right
side of the threads (in the
perspective shown above) the better
it will cut, as the sharp edge cuts
cleanly into the plastic. When the
threads are cut, remove the
fitting, wrap with Teflon tape and
re-install. Be sure to turn the
fitting in fully past the cross cut
so air cannot escape back out of
the groove if you are using this
technique on a high pressure
system. When making the muffler, no
tape is needed.
Here is yet another way to use your
compact muffler. These photos,
which was first used in the 2003
project, the
Lynching, shows a second
fitting on the top side of the
muffler that can be used to silence
the exhaust from the secondary air
inlet on a 2 way air ram. You must
route these two lines into the
muffler separately, as if you
 link
them together, you will in essence
be attempting to force air into
both the PUSH inlet and the PULL
inlet of the same air ram.
So there is the first step in
making an air-activated scare
event. If you would like to see the
trigger in use, you can visit one
of my other how-tos on this like
the
Aerial Executioner.
If you want to automate the use of
your air props you can do that by
using an Event Control Timer (ECT).
You can learn more about it on the
Motion Trigger how pages.
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