A hacksaw is a hand saw with a fine-tooth blade that is fitted under tension in a frame. A hacksaw is used to cut the materials such as metals or plastics. A Hand-held hacksaw consists of a metal arch with a handle, usually a pistol grip, with pins for attaching a narrow disposable blade.
A screw or other mechanism is used to put the thin blade under tension. The blade can be mounted with the teeth facing toward or away from the handle, resulting in cutting action on either the push or pull stroke.
On the push stroke, the arch will flex slightly, decreasing the tension on the blade, often resulting in an increased tendency of the blade to buckle and crack
Cutting on the pull stroke increases the blade tension and will result in greater control of the cut and the blade has a long life.Â
Parts of Hacksaw/ Hacksaw Parts
The hacksaw is a hand tool used to cut metal. Its four main parts are frame, blade, handle, and adjusting wing nut. The frames on most hacksaws may be flat or tubular. Some hacksaws have adjustable frames to accommodate various hacksaw blade lengths.
There are two different types of hacksaw handles: a straight handle and a pistol grip handle. The pistol grip handle has the following advantages:
- The operator can give the required sawing effort in a direct line with the blade.
- There is less risk of twisting the blade when sawing.
Hacksaw Blade Position/Diagram
Hacksaw blades are made of high grades of steel such as tool steel, high-speed steel, or tungsten-alloy steel. The saw blades generally used are ½ in. (12.7 mm) wide, in standard lengths of 250 mm and 300 mm. There is a hole at each end of the blade for mounting it on the hacksaw frame. Two types of hacksaw blades are available – all hard blades and flexible blades. All hard blades are hardened at full length between the pin and the holes. In flexible blades, only the teeth are hardened. Because of their flexibility, these blades are useful for cutting along curved lines.
The distance between adjacent teeth is called the pitch. The various types of pitches in use are: coarse (1.8 mm); medium (1.4 mm and 1.0 mm); and fine (0.8 mm). It is important to use the right pitch for the work being cut. Select a blade as coarse as possible to provide plenty of chip clearance and cut through the work quickly. The blade selected should have at least two teeth in contact with the work so that the work cannot jam between the teeth and strip the teeth from the saw blade.
To prevent the saw blade from binding when penetrating the material, the cut is to be broader than the thickness of the saw blade. This is achieved by the setting of the saw teeth.
2 types of saw settings :
Staggered Set. Alternate teeth or groups of teeth are staggered.
Wave Set. The teeth of the blade are arranged in a waveform. Specification: Hacksaw blades are specified by the length, pitch, and type i.e., hacksaw blade 300 x 1.8 mm, low alloy all-hard.
Selection of Blade: The blade should be selected according to the strength and size of the material to be cut.
| S.No. | Material to be cut | Pitch in mm |
| 01 | Soft materials like copper, brass, lead, etc | 1.8 |
| 02 | Mild steel, cast iron | 1.4 |
| 03 | Medium carbon steel | 1.0 |
| 04 | High carbon steel, alloy steel, sheets | 0.8 |
The hacksaw blade should be selected according to the hardness of the metal to be cut. Fine-pitched blades are suitable for hard metals and coarse-pitched blades for soft metals.
The hacksaw blade should be selected according to the thickness of the metal to be cut. Fine-pitched blades are suitable for thin-section metals and coarse-pitched blades are suitable for thick-section metals
What is a Hacksaw Frame?
The frame is the main part of the hacksaw, which is fitted C-shaped. Its one head is fixed at the handle and the second side with tension sliding screw. The sliding screw of the outer surface has to thread a fly nut, which is moved over the threading of the blade in the frame.Â
3 types of hacksaw frames
which are given below
(i) Fixed Hacksaw Frame
This is made up of an iron sheet, which is C-shaped and bent at an angle of 90°. In which, we use only a single type of blade in length. If one size of hacksaw blade to be fitted is 200 mm blade. According to the handle, it is of two types.
(ii) Adjustable Hacksaw Frame
The adjustable hacksaw frame is divided into two parts so that its length can be increased or decreased with the help of a pin, i.e. fitted with a frame and its handle made up of wood, aluminum, etc. In this frame, the size of the blade varies from 200 to 300 mm.
(iii) Cutting Hacksaw Frame
It is also the same as the solid frame used for only one limited blade length. It has a deep rectangular steel frame and a die-cast aluminum handle with a front grip to enable deeper cutting. It has an alternative 55° sawing angle facility for flush cutting.
Hacksaw Blade Position/Draw and Label a Hacksaw
It is made up of high-carbon steel, tungsten steel, or high-speed steel. Its works depend upon the length, breadth, width, and teeth pitch of a blade.
A hacksaw blade is made too hard and tempered after making teeth and holes in the blade. Sometimes, hole parts of the blade must be annealed. The thickness of the blade is from 0.6 to 0.8 mm, width from 12 to 16 mm, and length from 250 to 300 mm.
According to the hardness of teeth, it is of two types
The distance between both holes is known as the blade’s length. The distance between the two corresponding points is called pitch.
(i) All Hard Blades
It is made up of carbon steel or speed steel. It is hard and tempered and has an easily broken tendency because, it has no flexibility and its teeth have long time efficiency so that, it is used by skilled workers.
(ii) Half Hand BladeÂ
This type of blade has only half teeth and is tempered so that, it is flexible. It is not broken easily and teeth have a short age. It is commonly used by skilled or unskilled workers for cutting metal.
The setting of the teeth of the hacksaw blade is bent
The setting of teeth means that the teeth of the blade are bending towards right and left. So that the cut does not go in deeper and there is no tendency for the blade to stick in the slot.Â
Type of hacksaw blade teeth
According to disbalancing of teeth, it is of three types, which are as follows.
(i) Single Staggered Setting
In this blade set, one tooth of the blade is bent to the left and the second towards the right and every fifth tooth is not bent so that, waste comes out freely. This type of setting is done in a coarse pitch blade.
(ii) Double Staggered Setting
In this setting, two teeth are bent towards the left and right, and then one tooth remains in a straight position.
(iii) Wave Setting
This is also called a zig-zag setting. In such a way, some teeth are bent towards the left and right. This is generally done on a fine-pitch blade.
Specification of Blades
| 01 | Length | 300 mm |
| 02 | Width | 0.08 mm |
| 03 | Pitch | 0.08 mm |
| 04 | Breath | 13 mm |
| 05 | Type | Hard or flexible |
Specification of Power Saw Blades
| 01 | Length | 600 mm |
| 02 | Width | 2.25 mm |
| 03 | Pitch | 0.4 mm |
| 04 | Breath | 4.5 mm |
| 05 | Type | All hard of flexible |
What is Power Saw?
A power saw is a tool run by sources of electricity or power sources such as electric motors, internal combustion engines compressed air, etc. It is used to cut big size of wood pieces, that are not possible to cut with manual hand tools. In this operation, the workpiece should be tightened with vice and should be used the coolant to cool the blade.Â
4 Types of Power Saw
According to the construction of the blade, it has four types. list below.
(i) Reciprocating Power Saw
The cutting action is achieved through a push and pull in reciprocating motion of the blade similar to work such as a hacksaw. This works on two types of mechanisms ie., mechanical and hydraulic. Both mechanisms are used by reciprocating power saws.
In mechanical mechanism, the blade is moving up and down in hydraulic and reciprocating motion. A power saw is a very long, large width and strong blade as compared to a hacksaw. Sometimes, there is also used hydraulic pressure, which helps to increase the age of the blade and efficiency.
(ii) Band Power Saw
It consists of an endless teeth steel belt that runs between two wheels. It is a powered machine. It is also known as a band saw.
A machine is used for sawing logs, beam boards, and wood materials, its cutting member is stretched between pulleys. The band saw has horizontal and vertical shape saws. It consists of two pulleys one is the driving pulley (in vertical machines, the lower pulley), and the other pulley is equipped with a device for tensioning the saw.
According to the working purpose, band saws are classified as heavy-duty machines, which are used for lengthwise sawing of logs and blocks. Medium-duty machines are used for lengthwise cutting of boards and blocks. Duty (carpenter) machines are used for lengthwise assorted other sawing of wood and various wood materials.
Band saws are characterized by high cutting speeds (up to 50 m/s) and narrow cuts (0.7-2.4 mm). The feed rate for heavy-duty band saws can be high 150 m/min. On such machines, it is possible to select the cutting pattern.
(iii) Circular Power Saw
A circular saw is a power saw, that uses teeth or an abrasive disc or blade (which shapes such as a circular plate) to cut different materials by using a rotary motion.
A circular saw is used to cut many materials such as wood, masonry, plastic, metal, etc., and may be handled or mounted to a machine. Circular saws are commonly powered by electricity but may be also powered by a gasoline engine or a hydraulic motor, which allows it to be fastened to heavy equipment, eliminating the need for a separate energy source.
(iv) Profile Power Saw
Profile power saw is used for a variety of cutting tasks with both wood and metal. It makes straight cuts and is curved also because it has a skinny and narrow blade.
The blade is tied up in a thin metal band, which is moved by pulley is placed over and under the cutting table with maximum adjustable distance between the table and the top. It is mostly used for wood designing in the carpentry shop.
Precautions While Cutting with Power Saw Machine
(i) Keep the upper and retracting lower blade guard clean and dust-free of the saw.
(ii) Do not use a saw that vibrates or appears unsafe in any way.
(iii) Check the retracting lower blade guard, has returned to its starting position before laying down the saw.
(iv) Do not overreach, keep proper footing and balance.
(v) Use always two hands to operate saws one on a trigger switch and the other on a front knob handle.
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