8 SERVO 08.2014
Q. I’m working on a pneumatic robot arm. So far, it functions well. The problem is, it’s extremely noisy. I added a long PVC tube to the discharge
line. That cut down on the hissing noise, but it also
slowed down the response of the arm. Is there an
affordable muffler device made specifically for
pneumatics?
— Wendy
A. You have discovered what others before you have discovered when working with pneumatics; namely, that all that escaping air whistling around makes a
lot of noise. I’ve found two types of pneumatic mufflers
that quiet air exhaust down quite a bit. The first type has
a sintered bronze insert or block (resembling an aquarium
air stone). The second type actually looks like a lawn
mower muffler, and has expansion chambers and baffles
in it to reduce the air noise without affecting velocity. I
found no one talking about the potential for taking a
power hit by using pneumatic mufflers, but I can’t
believe that the issue isn’t there.
If you slow the exit of the air from a cylinder, you will
slow its motion; that just seems logical. The lawn mower
type of pneumatic muffler, however, has construction that
is similar to an internal combustion muffler. The IC engine
muffler is designed to avoid back pressure to the engine
which has a similar affect — a reduction in engine power.
I would look into the latter pneumatic muffler type and
see how that affects your machine. National Pneumatic
makes the most promising one that I found; their Series
86 pneumatic mufflers might just fit the bill.
Q. I added a projectile launcher to my combat bot. It shoots large nails that I’ve sharpened with a grinding wheel. My problem is finding an
affordable target to test the system indoors. I’ve tried
foam-filled archery targets, but the nails get embedded
and I can’t remove them. Plywood doesn’t work because
the nails often ricochet. Any ideas?
— Ralph
by Dennis Clark
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ummer is upon us and everyone is busy building and testing robots, right?
Right. That includes me. I'm getting ready for the competitions in the
coming months. Here in the Colorado Rockies, our robotics club is reorganizing to push our hobby forward. You can only build so many beginner
robot projects before they start looking like coffee commercials on TV. If
your local club is running out of hobbyists, you might want to consider doing the
same thing. Our plans include keeping at least one entry-level competition going, like
mini Sumo. This works great as a "king of the hill" competition where the current
leader resides at the clubhouse and challengers can pick on him/her whenever they
feel up to it. Let's face it, the bot owner doesn't even need to be there, right? We are
also going to plan group build activities and quarterly challenges for "social robots,"
"musical robots," and advanced robot projects like common robot communications
networks and the like. Folks’ ears really perked up when we started doing this
brainstorming stuff!
To be truthful, I’m as busy as the rest, so this month is dedicated to clearing out
questions that I've been pondering, but have not yet written about. So, without any
further discussion, let’s get into it!
S
