22 Art Jewelry ■ March 2016
Clamps can be grouped into four general
types based on their classification of work-
ing: wedge, screw, spring, and toggle.
Wedge clamp
This mechanism probably predates the
other types of clamp, and is based on two
simple machines: the wedge and the lever/
fulcrum. A ring clamp is the most com-
mon example used by jewelers. They are
made from wood, plastic, or metal. They
usually have one rounded end and one
straight, with leather inserts so as not to
mar the metal being held and to provide
a secure grip. Use them to hold rings, wire,
and small pieces of sheet, and to grip wire
when coiling it to make jump rings. They
are cheap and should last a lifetime.
A ring-setting clamp technically falls
into the screw-activated category, but it’s
designed to hold a ring, so I wanted to
mention it here. When you tighten a screw
on the clamp, a nylon sleeve expands
inside a ring shank, holding it securely.
I picked one up at Harbor Freight and
was surprised at the quality. Mine was
made in India and came in a nice wood-
en box with clear instructions.Screw clamp
Screw clamps use a screw to exert pressure
for holding things in place. The first thing I
look for when I teach a workshop at a new
location is the milk crate full of C-clamps.
Why? Because they are versatile. They’re
used to hold down bench pins, tabletop
machines (like a drill press), bench vises,
and other tools that would normally be
bolted down. C-clamps are also great for
holding wood or other materials together
when using adhesives. Most C-clamps are
made from malleable iron, for safety. You
would not want a C-clamp made from a
brittle material, as it could break apart ifexcessive force is placed on it. I have some
that are made from cast steel, aluminum,
iron sheet, brass, and plastic. The nonfer-
rous clamps are small and should be used
only for light-duty work.
Another type of screw clamp is called a
bar clamp. I have a set of brass bar clamps
that I use only with wood or plastic when
making box forms. The bars are 10 in.
(25.4 cm) long, and are small versions of
woodworkers’ bar or pipe clamps. You can
get them from most hardware stores and
model-building suppliers.
In this family of screw clamps is the
toolmakers’ parallel clamp. Design-wise,
this is identical to the parallel clamp used
by woodworkers — only smaller. Unlike
C-clamps, toolmakers’ clamps are made
from hardened steel. There’s no fear of the
steel jaws breaking, because the pressure
exerted on them comes in the form of
compression. They use two screws instead
of one to tighten. An American-made
Starrett parallel clamp can cost $60, and
that’s for a clamp only 1^1 ⁄ 2 in. (38 mm) long.
Check flea markets for one of these, as
most people don’t know what they are.
They are sweet.Hang On
by Christopher C. Darway
S
tudies have shown that the human thumb and index finger can
exert 15–19 lbs. of pressure. Those researchers were never in my
homeroom to experience a pinch by that miscreant Ricky Folger
(who I swear generated 1,900 lbs.). Nor did they have Aunt Ethel,who unleashed her death grip on my cheek at family gatherings and left a
welt. Our hands, with those wonderfully opposable thumbs, enable us to
make things. We use these digits as tweezers, grippers, and clamps. But,
like all mortals, we can use help. Enter the clamp.
STUDIO SAVVY
Ring clampRing-setting clampToolmakers’
parallel clampV-block and screw clamp