METALWORK HAND TOOLS – I

TOPIC: METAL WORK- HAND TOOL-Marking out and measuring tools

Metal is one of the materials used in technology for the construction and fabrication of devices. Metal as a material can be fabricated into various shapes and products. However, to be able to do that, you need appropriate tools.  These tools are either hand tools or machine tools

MARKING OUT TOOLS:

Marking-out tools are hand tools used for making lines on metal surfaces, checking alignment, and indicating points or positions on a workpiece.Tools for making out in the workshop include: 

1.          Surface plate 

2.          Surface table

3.          Scriber

4.          Odd-leg caliper 

5.          Divider 

6.          Punches

7.          Try square

8.          Box Square 

Surface plate  

The surface plate is a precision piece of equipment with a flat surface of the high-grade finish, on which workpieces are placed for marking out. It is also used for testing the flatness of surfaces.

Care of surface

1.           Cover the surface after use to keep it free from dirt

2.           Do not hammer it.

3.           Do not scratch or deform the surface

Surface table

The surface or marking out table is larger than the surface plate. It is used for supporting bigger workpieces so that marking out can be carried out with ease and accuracy. It is made up of cat iron and has a high-grade surface.

Scriber

The scriber is the metal worker’s pencil. It is used for marking out lines by hand and together with straight edges like steel rules, try squares, or box rules. It is made from high carbon steel or stainless steel, hardened and tempered. They are of various sizes.

Divider  

Dividers are two-legged steel instruments used for scribing arcs, and curves and for setting off distances. Dividers are available in various sizes and may be available in various sizes, and maybe spring-loaded with a fine adjusting screw, or maybe firmly joined at the head.   

Punches 

This is either a medium or high carbon steel material. We have the dot punch and the centre punch.

Dot Punch: This is used for denting scribed lines. This is done some space apart; to make the lines indelible while one is working. It is 600 at its conical end.

Centre Punch: It is used for providing a heavy conical dent at the end point where a hole will be drilled in a workpiece. This prevents the drill from deviating from the current location of the hole. It is 900 at its conical end.

 Try square:  The try square is used for testing the squareness of the surface, and marking out lines at right angles to given edges. It is a high-precision tool that should be handled with care. The stock and the blade, which are the main parts, make 900 with each other

Box Square:  The box square is used for making parallel lines on a round bar, It is made from medium carbon steel (hardened and tempered) and has graduations on its body to facilitate marking off dimensions, while marking out 

Evaluation 

1.          Define marking out tools 

2.          State 8 marking out tools and their uses.

MEASURING TOOLS 

Measuring tools are tools for measuring lengths, widths, thicknesses, or sizes of metals. Measuring is usually done during marking out.

Common measuring tools include the following:

1.          Steel rule 

2.          Caliper   

3.          Combination sets

4.          Micrometer

5.          Vernier Caliper 

6.          Depth gauge 

7.          Height gauge  

Steel rule  

The steel rule is made of carbon steel or stainless steel. It is graduated in millimeters and centimeters. To measure with it, the steel rule should be placed on its edge to touch the work, so that an accurate reading can be taken from the centre of the division lines.

Caliper    

Calipers are used for measuring the diameters, width, and thickness of objects.

We have:

1.          External Caliper: It is used for measuring diameters, width, and thickness from the outside of the objects.

2.          Internal Caliper: It is used for measuring diameters, width, and thickness from the inside of the objects.

3.          Odd-leg Caliper: It is used for measuring diameters, width, and thickness from the middle of the objects to the outside.

Combinations sets

The combination set, as the name implies, is a measuring instrument, which consists of three heads: 

1.          The centre square: It is used to determine the centre of round shafts or holes

2.          The square head: It is used for measuring and setting out 900 and 450 angular surfaces. It is a standard tool, which requires no setting.

3.          The protractor head: It performs dual functions as (i) marking out tool and (ii) measuring tool. It is a semicircular precision tool for measuring angular surfaces. It is graduated between 00 and 1800.

Micrometer 

It is used for taking precision measurements. We have both internal and external micrometers, which are used for measuring the diameter of small objects in millimeters.

Vernier Caliper  

It is used for both external and internal precision (accurate) measurements of objects in centimeters.

Depth gauge 

It is used for measuring the depth of holes similar to that of an outside micrometer.

Height gauge

It is used to perform two functions namely:

1.          To determine the height of components.

2.          To mark out dimensions.

GENERAL EVALUATION

1.          Define measuring tools 

2.          State 5 measuring tools and their uses.

3.          Define marking out tools 

4.          State 8 marking out tools and their uses.