HAND TOOLS
By C. Namacha
What are hand tools
A hand tool is any tool that is powered by hand rather than a motor.
Any of the implements used by craftspersons in manual operations,
such as chopping, chiseling, sawing, filing, or forging.
Hands are treated in special ways of heat treatment of metals to
improve some mechanical properties such as hardness, ductility,
strength. (heat treatment method to be learnt later)
Power tools – usually handhled motor-implements such as an
electric drill or electric saw perform many of the old manual
operations and such may be considered hand tools
The oldest known hand tools date from 3.3 million years ago, it was
from a sharpened stone for cutting.
Classifications of hand tools
Hand tools are literally classified according to the function their
preform
Some of the classification of hand tools include:
1. Marking out tools
2. Lay out tools
3. Measuring tools
4. Cutting tools
5. Holding tools
6. Striking tools
It must be noted that two classes of tools might be combined into one
Marking out/laying out tool
Marking out tools – these are hand tools used for marking out
required metal before cutting in the metal workshop
Laying out is the marking of lines, circles and arcs on metal
surfaces; such work is called layout work
It is the transferring of information from a working drawing to metal
surfaces to show the machinist or the fitter at the workbench how
much metal should be cut away
Before you perform any hand processes or machining on the metal
you need first to clearly mark out required metal part
Marking out helps to know parts of the work that must removed by
cutting, grinding, chiseling, filing
Marking out also helps an operator to see clearly centres of holes
for drilling
Marking out tools/laying out tools
Examples of marking out tools in metal work
i. Scriber
ii. Dot punch
iii. Centre punch
iv.Divider
v. marking ink,
vi.marking out datum surface
Marking out lines
i. Datum lines – datum refers to a fixed or starting point, line or
surface. A marking out operation will be more accurate if all
measurements are from one datum point
ii. Marking points – to measure a point on a marked line use a V
marking. Scribing a line through the point of the V will give an
accurate position of the marked line
iii. Centre lines – centre lines are scribed at required distances from
the datum features to establish the positions of holes, slots, radii and
other details. Holes and radii centres require two centre lines to
form a cross.
iv. Outlines – outlines show the dimensions of the work piece and
indicate the location and amount of metal to be removed. Lengths,
widths, thicknesses, angles diameters, and radii are outlines which
determine the finished shape
Scriber
A scriber is a piece of high carbon steel hardened and tempered,
generally about 6” to 10” long, pointed on one or both ends like a
needle
Tools are treated to achieve specific mechanical properties i.e.
hardness, toughness, ductility or improving brittleness
A scriber is treated by first hardening and then tempered. This
processes makes the scriber wear-resistant, tough, more ductile
and improves its brittleness.
scribes produce marks on other metals by denting hence they must
be wear-resistant and must not crack or break easily
Hold a scriber like a pencil to scratch or scribe straight lines on
metal.
Scribers with bent end are used to scratch lines in places where the
Safety precautions when using
a scriber
Scribers must be carried with the point
facing down
Never place a scriber in your pocket
To maintain a sharp end of the scriber,
sharpen the point part on the oilstone
Punch
A punch is a tool used to indent or create a hole through
a hard surface.
They usually consist of a hard metal rod with a narrow tip
at one end and a broad flat at the other end.
When used the narrower end is pointed against a target
surface and the broad end is then struck with a hammer
or mallet, causing the blunt force of the blow to be
transmitted down the rod body and focused more
sharply onto a small area.
There are two types of punches in metal technology:
centre punch and dot punch
Centre punch
A centre punch is used to mark the centers of holes that are to be
drilled.
A drill has a tendency to wander if it does not start in a recess. A
center punch forms a large enough dimple to guide the tip of the
drill
They are made from high carbon steel hardened and tempered
(wear-resistant, improves brittleness, toughness)
The point angle of the centre punch is between 60 degrees and 90
degrees.
A ball pein hammer is used in conjunction with the centre punch
when marking the centre of holes to be drilled
The centre punch should be firmly held while in use
Dot punch
The dot punch is a lighter and thinner version of
the centre punch and is used basically for the
same job
Other works requires you start with a dot punch
and then a centre punch
Dot punches are more accurate as the dot
produced is smaller
The sharper point is ground to an angle of 60
degrees by holding it tangentially to a tool
grinder and rotating it.
Divider
An instrument for measuring, transferring,
or marking off distances, consisting of two
straight adjustable legs hinged together
and ending in sharp points
It is used principally in drafting for the
accurate transfer of dimensions from a
measuring scale
In machine shops for scribing lines on
surfaces, usually machined, with
dimensions taken from a ruler
Marking ink / engineers layout ink
A dye used in metalworking to mark out metal parts for machining
or pre-manufacturing
Applied as a very thin layer of dye onto hard surfaces like metal or
glass, it can be etched with a scriber or other sharp instrument to
reveal a narrow line in the metal underneath
The color of the coating substance should be in contrast to the
surface color of the work
For rough surfaces, chalk rubbed in or water is commonly used. For
machined or finished surfaces, a blue marking out dye can be used
Marking ink can be easily removed with methylated spirit
Holding tools
A holding tool is a support device often used in the
manufacturing industry to securely position a tools in a
specific spot or orientation
Some of the examples of holding tools in metal technology;
i. Vices: metal bench vice, hand vice, machine vice,
clamps (pliers, tool makers clamp)
ii. clamps: G-clamp, F-clamp, Sash-clamp
iii. Angle plate – box angle plate, fixed angle plate,
adjustable angle plate
iv. Adjustable swivel block
Vices
A vice or vise is a mechanical apparatus used to secure an object
to allow work to be performed on it. Vices have two parallel jaws,
one fixed and the other movable, threaded in and out by a screw
and lever
There are many types of vises some are bench vise, machine vise
and hand vise
A bench vise also called an engineers vise/metalworking
vise/machinists vise is used to clamp metal instead of wood
Machine vises are mounted on drill presses, grinding machines and
milling machines.
Leg vise or post vise, which is attached to a bench but also
supported from the ground so as to be stable under very heavy use,
as by an auto body repairman or blacksmith
Bench vice
Machine vise
Leg vise
Clamps
A clamp is a fastening device used to hold or secure
objects tightly together to prevent movement or
separation through the application of inward pressure
There many types of clamps available for many different
purposes. Some are temporary, as used to position
components while fixing them together, others are
intended to be permanent.
Some examples of clamps used in mechanical
workshops include G-clamp/ C-clamp, F-clamp
G-clamp
F-clamp
Vee-Block
V-Blocks are precision metalworking jigs typically used
to hold round metal rods or pipes for performing drilling
or milling operations.
Consist of a rectangular steel or cast iron block with a
120 degree channel rotated 45 degrees from the sides,
forming a V-shaped channel in the top
A small groove is cut in the bottom of the V. They often
come with screw clamps to hold the work.
There are also versions with internal magnets for
magnetic work-holding.
V-Blocks are usually sold in pairs
Angle plates
An angle plate is a work holding device used as a fixture in
metalworking
Angle plates are used to hold work pieces square to the table
during marking out operations.
Adjustable angle plates are also available for work pieces that
need to be inclined, usually towards a milling cutter
Angle plates are made from high quality material (generally
spheroidal cast iron) that has been stabilized to prevent further
movement or distortion.
Slotted holes or T bolts slots are machined into the surfaces to
enable the secure attachment or clamping of work pieces to the
plate, and the plate to the worktable.
Fixed angle plate
Box angle plate
Adjustable angle plate
