FIBEROPTICS BY JIM HAYES
To terminate fiber with epoxy/polish
connectors, you only need a basic tool
kit and an epoxy-curing oven, which is
a temperature-controlled, electric oven
that cures epoxy in about five minutes.
Most of these ovens require alternating
current (AC) power, which is no problem
in most premises applications, but, as I
bragged in an earlier column, I invented
one that works on battery and AC power
for use anywhere. It’s still available.
When you arrive at a work site, set up
your workspace. Plug in the oven to let
it heat up fully. In most cases, you need
ample room for all of your tools and a
small folding table covered with a black
plastic mat so you can see the fiber more
easily. Once you become experienced,
you will develop strong preferences for
tool placement and creation of the most
Experienced techs know to use only
the proper adhesives in the specified
manner. Much research has gone into
finding the right kind of adhesive to
bond glass fibers to ceramic ferrules in
connectors, including how to apply the
adhesive and how to cure it.
Only buy your epoxy from a quality
fiber optic distributor. Ensure the adhesive is fresh (it’s dated like food, and you
should store it in the refrigerator), and
mix it thoroughly to ensure the adhesive
and hardener are fully combined.
After mixing, the adhesive is poured
into a syringe with a flat-ended needle.
Most adhesives have only about 30
minutes of working life, so you need to
plan ahead to get the most use out of the
epoxy. If all of your cables are prepared
with only the tight-buffered fibers left to
strip, you can get more than a dozen connectors from one batch of epoxy.
The syringe squeezes adhesive into
the connector. Insert the needle into
the back of the connector, hold the flat-tipped needle against the end of the
ferrule and squeeze gently until you see
a small bead of adhesive on the end of
the ferrule. Back the syringe out a bit,
and squeeze just a tiny bit more into the
back of the connector. If adhesive runs
out the back of the connector, you overdid it. Remove the syringe, and place it
on the table on top of a lint-free wipe.
Inserting the fiber into the connector
is easy once you get the hang of it, even if
the fiber and the hole in the ferrule are the
size of a human hair. Connec-
tor manufacturers have thought
about that, so there is a chamfer on
the hole to guide the fiber.
Here is another trick. While you
insert the fiber, slowly rotate the connector back and forth to spread the
adhesive evenly. The surface tension
of the adhesive will “float” the fiber
into the center of the hole in the ferrule, improving fiber alignment in the
connector and improving the polishing process. That trick will noticeably
reduce your connectors’ loss.
If you are terminating tight-buffer
fiber (the fiber with the 900-micron
plastic coating), all that is left is to slip on
the boot and place the connector in the
oven to cure. If you are using a jacketed
cable, crimp the strength members to the
connector, slide the boot on the connector and place it in the oven.
Here is where epoxy/polish connector critics get confused in talking about
termination times. You don’t wait around
for that connector to cure before polishing it. You prepare another connector
and put it in the oven, then another and
another. Most ovens have about 20 positions for connectors (the oven I designed
holds six connectors). By the time you
get the sixth connector in the oven, the
first one is ready to come out. If you are
terminating a number of connectors,
the oven curing time is irrelevant. You
simply go on to the next connector. The
curing time only matters when you are
only doing one or two connectors.
With epoxy, connectors come out
of the oven ready to polish—a process
that takes less than a minute. Setting up
a production line will enable a tech to
easily complete a dozen connectors an
hour, twice that if they are skilled and in
Next month, the process continues.
HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find
The art of installing fiber optic connectors, part 4
him at www.JimHayes.com. I S T
Only buy your epoxy
from a quality fiber optic
distributor. Ensure the
adhesive is fresh
(it’s dated like food, and
you should store it in the
refrigerator), and mix it
thoroughly to ensure the
adhesive and hardener
are fully combined.
Stick ’em Up Using Epoxy
I AM ALWAYS AMUSED WHEN I HEAR, “No one uses heat-cured epoxy
connectors anymore.” In fact, about 95 percent of all connectors,
including every factory-made patchcord, uses heat-cured epoxy
for its ease of use, low cost and high reliability. Granted, only the
most skilled techs use them in the field, but they know the
secrets of working with these connectors.