Sawing Explained: Hacksawing, Bandsawing and Circular Sawing

It is a machining operation in which a narrow slot or cut is generated in the work, mainly to break it into two. Sawing operations are, therefore, known as cut-off operations. These are an indispensable class of machining operations that are required in the course of tool making.

The cutting tool is a sawing blade that consists of narrowly spaced sharp teeth that perform the sawing operation. Usually, the work is held stationary in the work-holding device, and the sawing blade, while moving in a reciprocating manner, does the cutting.

Types of Sawing

There are three major types of sawing, which are described below:

  • Hacksawing
  • Bandsawing
  • Circular sawing

Hacksawing

image of hacksawing

It is the most common type, as shown in the figure above in which the workpart is clamped static while the blade moves linearly in a reciprocating fashion.

It is basically used as a cut-off operation with the blade that does the cutting only during the forward stroke, compared with bandsawing and circular sawing in which the sawing operation is continuous.

The blade is driven either manually or using a power hacksaw. The machining tool used to perform hacksawing is known as a hacksaw. It is illustrated below.

power hacksaw

The hacksaw blade has a tough alloy steel back and carries electrically welded high-speed steel teeth. It is shown below.

hacksaw blade

Bandsawing

bandsawing

It is a linear yet continuous sawing operation in which the blade (now known as a bandsaw blade) is formed into a flexible loop with teeth on one edge.

The respective machine is known as a bandsaw, as shown schematically below, which provides a drive mechanism for the continuous running and guiding of the bandsaw blade past the work.

bandsaw

Bandsaw is available in either horizontal or vertical configuration depending on the direction of the saw blade motion.

Vertical type, as shown below, is used for cut-off operations along with contouring and slotting. Slot sawing gives an advantageous machining quality. In the contour sawing, the work is fed into the sawblade.

slot sawing
contour sawing on vertical bandsaw

Bandsaws are available in both manual and automatic modalities. In the manual type, the operator feeds and guides the work into the bandsaw blade. Whereas, in the automatic type, feed is provided to the work by an electric motor.

The figure below shows a man cutting a marked timber on a bandsaw.

Circular Sawing

circular sawing

Used to cut long bars and tubes, the circular saw uses a rotating saw blade that does the cutting by moving past the workpart.

Circular sawing is akin to slot milling; the difference lies in the design of the cutter: in the case of circular sawing, the saw blade is thinner, sharper, and contains many teeth compared with the milling cutter, which has few cutting teeth and is relatively heavy.

The circular saw, as schematically shown below, uses a powerful spindle for holding and rotating the saw blade. It also provides a feeding mechanism to the saw blade for rotating into the work.

circular saw

Two further types of circular sawing are known as abrasive cut-off and friction sawing. An abrasive disc is used to see heavy materials in case of an abrasive cut-off.

Whereas, in friction sawing, a steel disc is used to cut by rotating faster into the work thus generating enough heat due to friction to soften the metal and thus breaking it.

Comparison between hacksaw, bandsaw, and circular saw

Differential ElementHacksawBandsawCircular Saw
Design and Blade TypeNarrow straight blade under enough tensionA continuous loop of toothed blades over two rotating wheelsNo, in most the cases
Cutting CapacityLow and preciseHigh with curved cutsVersatile; Depends on blade diameter
Cutting AccuracyCompromisedHigherHigh when used with guides
Speed and EfficiencySlow and less efficientFaster and efficientFaster and more efficient than a hacksaw
PortabilityyesA continuous loop of toothed blades over two rotating wheelsNo in most the cases
ApplicationsPlumbing, metalworkingCurved cuts, resawing lumber, irregular shapesFaster and more efficient than a hacksaw

Frequently Asked Questions

What is the deciding factor that determines which powersaw is to be used?

The selection of a particular powersaw is governed by factors such as the nature of the cutting operation, material to cut, precision, and accuracy among others.

Which powersaw is mainly used for woodworking?

It is a bandsaw that is preferably used in woodworking for cutting curved and intricate designs.

What are the safety precautions that must be followed when operating a hacksaw?

Use PPEs such as gloves and goggles. Secure the work in vice firmly to keep it from being loose.

Is it possible to cut curves with a circular saw?

Yes, but it is chiefly designed to cut straight cuts in wood. With high machining prowess and learned practice, one can cut gentle curves with a circular saw as well.