J.S.S 1 BASIC TECHNOLOGY 3RD TERM | METAL WORK HAND TOOLS

LESSON PLAN

WEEK 3

DATE: 12th – 16th May, 2025

CLASS: J.S.S 1

SUBJECT: BASIC TECHNOLOGY

TITLE: METAL WORK HAND TOOLS

SUB TITLE: MEASURING TOOLS, MARKING OUT TOOLS, WORK HOLDING DEVICES

PERIOD: DOUBLE

DURATION: 80 MINS

LEARNING OBJECTIVES: At the end of this lesson learners will be able to:

Identify the various tools used for metalwork.
Highlight some examples of each of the tools.
State the uses of each tool
Sketch each of the tools

KEY VOCABULARY WORDS: Holding, Measuring and Marking out

RESOURCES AND MATERIALS: Diagram showing metal work measuring, marking out hand tools such as Scriber, calipers (Inside, Outside, odd leg) surface plate, etc.

NERC Basic Technology for junior secondary school 1

BUILDING BACKGROUND/ CONNECTION TO PRIOR KNOWLEDGE: Students have visited metal workshop to see the use of some metal tools.

CONTENT:

Metalwork hand tools are hand tools that are used in the metalworking field solely operated with human efforts. They include measuring tools, marking out tools, cutting tools, driving tools, boring tools and

work holding tools.

MEASURING TOOLS

A measuring tool is a device used for measuring a physical quantity. Some of the existing tools are: Steel Rule (Engineer’s Rule), protractor, vernier caliper, Micrometer screw gauge etc.

The steel rule: is also called engineer’s ruler. It is made of carbon steel or stainless steel. The size commonly used is the 300mm and 150mm lengths. The steel ruler works with dividers and the calipers. The steel ruler is also used along with the calipers; after the calipers have been used to take a measurement, the measurement taken is translated into millimetres on the steel ruler.
Protractors: It is an instrument for measuring angles in metal work. The try square can be used for checking a 900 or a right angle only, but the protractor can be used for checking any angle.

MARKING OUT TOOLS

Before metals can be measured and cut, they should be marked. The tools used to mark the sheet metals are called marking out tools. They include surface plate, scriber, odd-leg, calipers, etc.

1, The Surface Plate:

The surface plate is a small table with a flat surface. It is used to test whether other surfaces are flat enough. It is also used as a surface to mark out metals.

Scriber:

A scriber is made of a tool steel and has a sharp point to scratch a line on a metal. The point is sharpened by holding the scriber at an angle on a power grinder and rotating it.

Calipers:

Calipers are used to mark as well as to measure metals. They are used to measure the diameter of the objects being formed. There are about three types of calipers; outside calipers, inside calipers and odd-leg calipers.

Outside calipers are used to mark the outside of bars and rods while inside calipers are used to mark the bore of tubes and the tone-ness of parallel surfaces. The odd-leg calipers are used on the lathe for scribing a line round the work. They are also used for marking the center of the end of a bar or for drawing lines parallel to a straight edge.

Dividers:

Dividers are used for marking out circles, arcs and radii. The length of the legs determines the size. The legs are made of steel and the top hoop of spring steel.

HOLDING DEVICES

It is necessary that there should be a means of holding wood and metals firmly on a workbench or on a machine tool in order to have a successful operation on them. Examples of some holding devices are bench hook, bench vice, G-Clamp, sash clamp etc. The work holding devices to be considered here include vices and clamps.

Vises –

Bench Vise: Bench vice is used to hold wood and metal for filing, sawing, chiseling and tapping. They are fitted into the edge of the workbench by bolts and nuts. They have serrated jaws for proper gripping the jaw is tightened by rotating the bar.
Hand Vise: The hand vise is not fixed to anything as the bench vise, it is held by the hand. The work piece is put in between the two arms of the vice and it is tightened by means of screw.
Machine Vise: The machine vise looks like a bench vise, it is however not fixed on the machine tool bed. It can be rotated for machining at any desired angle.

Clamps –

Corner Clamp (Metre Clamp): This is used to hold work piece at right angle while gluing and pinning.
Sash Clamp: This is a large clamp used for holding and drawing parts of a work piece together while gluing. It is also called T-Cramp.
‘G’ and ‘F’Clamp: This is a metal clamp used for holding a work piece while sawing or chiseling.
Bench Holdfast: This is also used to hold job firmly on the bench when moulding or rebating.
Pliers: Pliers are work holding devices held in the hand of users. It is used for gripping and cutting wire and thin metal sheets. Pliers come in different forms, their forms give them their different names mentioned below:
long nose pliers ii. cutting pliers iii. gripping pliers and iv. combination pliers