O&MM Fabricator - November/December 2017 - 38

PHOTO CREDITED TO: BRIDGETOWN FORGE

Relaxed grip not only reduces hand shock,
but imparts a whip like motion at end of
hammer strike.

Central to the Hofi system is the hammer.
This is where the work is done. The handle
is, much like an airplane wing, deceptively
simple in appearance. The Hofi hammer's
handle is noticeably shorter than most forging hammers. "A shorter hammer gives you
greater control," says Kartmazov. "A lot of
smiths choke up on the handle anyway, so
the excess length is wasted."
The handle is squared rather than oval, so
it may be held lightly with just two fingers.
The light, two fingered grip allows for the
hammer to actually swing slightly within the
grip, adding a few degrees to the total arc
and also producing a whip effect at the finish of the blow. The movement also involves
the shoulder, elbow and torso. This accomplishes several things. It allows more degree
of arc in the swing, and it amortizes the stress
over several areas rather than concentrating on one or two joints. The result is a very
hard hammer blow which is less damaging
to your body.
Unlike the majority of manufactured hammers, there is a certain amount of thought
that goes into its ergonomics. In addition to
its squared cross section, the handle flares
at the center of its longitudinal axis. This is
markedly different from the swell that some
manufacturers put in their handles. "This swell
is not good," explains Kartmazov. "It traps the
hand in one position on the handle. The Hofi
hammer has slight taper from its middle. The
proportion of the taper on the Hofi handle is
critical. As you swing the hammer, centrifugal
force makes it want to leave your hand. The
reverse taper wedges the handle into your

hand and resists it flying away. So you can
hold it more loosely." The squared cross section aids this as well. "Look at your fingers,"
says Kartmazov. "The bones are not curved;
they're straight. So when you bend them, it's
not an oval; it's a small rectangle." The hard
chines of the Hofi handle also reduce torque in
the strikes. The hammer resists turning in your
hand, keeping the blows much more accurate
when you're using the edges of the hammer
to fuller a piece.
There is a dividend of economy from this
technique as well. Steel has poor thermal
conductivity. It doesn't retain heat well and
metals that are to be shaped while hot must be
frequently reheated. Yet blacksmiths who use
proper ergonomics are able to move metal so
efficiently that the piece can often be worked
in a single heat.
Bad Vibes
It isn't just awkward positions and repetitive movements that injure a fabricator. The
hand shock and vibrations that result from
such common tools as power hammers,
saws, grinders, sanders, and virtually any
gadget capable of nibbling or kneading metal
will also damage the human body. This has
been documented in studies by Drs. Sandra
Govindaraju and Daniel Riley of the Medical
College of Wisconsin. The study, improbably,
involved shaking rats' tails for hours at a time
and measuring the resultant physical infirmities. They concluded that constant vibration
does indeed affect arteries, causing them to
constrict, starving nerves of adequate blood
supply. The result is damage to nerve cells, and
in cases of protracted insult to the arteries,
nerve cell death.
The consequence of vibration induced
nerve damage is numbness in the fingers
and hand. This condition, known as hand-arm
vibration syndrome (HAVS), can with a sufficient iteration, become permanent.
There are several ways to reduce the hand
shock from a power hammer. Proper technique
will help. Keep the steel hot, keep the steel flat,
and keep the steel loose. "There's less shock if
the steel is hot enough," explains Arnon, "but
a power hammer will expose weak technique.
You must keep the steel (workpiece) flat and
hold it loosely." Quality, purpose-designed
tongs are a must. This means no vice grips
or pliers.
The right top tools make a difference as
well. "You must have proper top tools," says
Arnon. "The heads can't be too tall or there's

38 | November/December 2017 * O&MM Fabricator

the danger of kick-out. And avoid wood handles. Weld a metal handle on it." Arnon's are
made from 5/8" or 3/4" braided cable.
On the Other Hand
What if, despite applied ergonomics and
your best efforts, you do manage to injure
yourself. At the risk of sounding flippant, work
through it, but use the other hand.
Peter Hapny, a Portland, Maine, blacksmith, has been down that rocky road and
offers this: "Learn to be ambidextrous."
When an acute tendonitis rendered his right
arm hors de combat, he simply switched to his
left hand. As with all ambidextrous training,
it was slow going at first, but in a short time,
the difference between right and left hand
became indistinguishable. Many people who
work with their hands have proven this. From
sculptor, Jeffrey Packard, who suffered a
stroke which incapacitated his right hand,
so he switched to painting and sculpting
with his left, to many surgeons, including
Dr. Kathryn Ko, a neurosurgeon in New York
who performs surgery and also paints, with
both hands.
Relax
So what can a general fabricator learn
from a blacksmith's ergonomic system?
Three things: Relaxation, Economy of Motion,
and Posture.
Whatever you're working on, make sure
your body is relaxed. Whether you're holding
a hammer, a top tool handle, or a bender lever,
avoid death grips on tools and controls. This
will cause your arm and shoulder to relax as
well. Shock and vibration does not transmit
well through a loose connection.
Relaxation allows for more efficient
motion. It involves more of the body than
just the hand. This allows you to work more
quickly, which preserves heat in a hot worked
piece, and it can even generate heat in cold
worked objects.
Finally, watch your posture. You should
be upright with knees slightly bent and feet
at shoulder width. If you find yourself bending over a work station, adjust your posture,
and if necessary (or possible), adjust your
work station.
This is the gospel according to Uri Hofi, and
it has been testified to by anyone who has ever
seen him work. All say they have never seen
anyone move metal as fast as this septuagenarian from Israel. And Hofi will be the first to
say, it's not him; it's the ergonomics.



Table of Contents for the Digital Edition of O&MM Fabricator - November/December 2017

President’s Letter
Letter From the Executive Director
NOMMA Network
NOMMA Education Foundation
First Look: 2018 Metalfab / Fencetech Attendee Brochure
It's in the Air
A Fabricator’s Ergonomics
Seven Costly Management Mistakes
Supplier Members
New & Returning NOMMA Members & Iron Club Members
Gold Members
High-Tech Laser Machine Allows Business to Boost Productivity and Expand Product Offerings
Index of Advertisers
O&MM Fabricator - November/December 2017 - intro
O&MM Fabricator - November/December 2017 - cover1
O&MM Fabricator - November/December 2017 - cover2
O&MM Fabricator - November/December 2017 - 3
O&MM Fabricator - November/December 2017 - 4
O&MM Fabricator - November/December 2017 - 5
O&MM Fabricator - November/December 2017 - 6
O&MM Fabricator - November/December 2017 - 7
O&MM Fabricator - November/December 2017 - 8
O&MM Fabricator - November/December 2017 - 9
O&MM Fabricator - November/December 2017 - 10
O&MM Fabricator - November/December 2017 - President’s Letter
O&MM Fabricator - November/December 2017 - 12
O&MM Fabricator - November/December 2017 - Letter From the Executive Director
O&MM Fabricator - November/December 2017 - 14
O&MM Fabricator - November/December 2017 - NOMMA Network
O&MM Fabricator - November/December 2017 - NOMMA Education Foundation
O&MM Fabricator - November/December 2017 - 17
O&MM Fabricator - November/December 2017 - 18
O&MM Fabricator - November/December 2017 - First Look: 2018 Metalfab / Fencetech Attendee Brochure
O&MM Fabricator - November/December 2017 - 20
O&MM Fabricator - November/December 2017 - 21
O&MM Fabricator - November/December 2017 - 22
O&MM Fabricator - November/December 2017 - 23
O&MM Fabricator - November/December 2017 - 24
O&MM Fabricator - November/December 2017 - 25
O&MM Fabricator - November/December 2017 - 26
O&MM Fabricator - November/December 2017 - 27
O&MM Fabricator - November/December 2017 - 28
O&MM Fabricator - November/December 2017 - 29
O&MM Fabricator - November/December 2017 - It's in the Air
O&MM Fabricator - November/December 2017 - 31
O&MM Fabricator - November/December 2017 - 32
O&MM Fabricator - November/December 2017 - 33
O&MM Fabricator - November/December 2017 - 34
O&MM Fabricator - November/December 2017 - 35
O&MM Fabricator - November/December 2017 - A Fabricator’s Ergonomics
O&MM Fabricator - November/December 2017 - 37
O&MM Fabricator - November/December 2017 - 38
O&MM Fabricator - November/December 2017 - 39
O&MM Fabricator - November/December 2017 - 40
O&MM Fabricator - November/December 2017 - Seven Costly Management Mistakes
O&MM Fabricator - November/December 2017 - 42
O&MM Fabricator - November/December 2017 - 43
O&MM Fabricator - November/December 2017 - 44
O&MM Fabricator - November/December 2017 - Supplier Members
O&MM Fabricator - November/December 2017 - 46
O&MM Fabricator - November/December 2017 - New & Returning NOMMA Members & Iron Club Members
O&MM Fabricator - November/December 2017 - 48
O&MM Fabricator - November/December 2017 - Gold Members
O&MM Fabricator - November/December 2017 - 50
O&MM Fabricator - November/December 2017 - High-Tech Laser Machine Allows Business to Boost Productivity and Expand Product Offerings
O&MM Fabricator - November/December 2017 - 52
O&MM Fabricator - November/December 2017 - Index of Advertisers
O&MM Fabricator - November/December 2017 - 54
O&MM Fabricator - November/December 2017 - cover3
O&MM Fabricator - November/December 2017 - cover4
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