Basic Cutting tool -hacksaw.pdf

This notes will be useful for ITI students to get a knowledge about hacksawing.

1. Basic workshop tools
MECH LAB
User | [email protected]







BASIC WORKSHOP TOOLS

2. Basic workshop tools
MECH LAB
User | [email protected]
HACKSAW

• Hacksaw is a cutting tool used to cut sheets, pipes
and various types of metals.
• The process of cutting metal using hacksaw is known
as hacksawing.
• Cutting action takes place only in forward stroke.
Main Parts of hacksaw
• The main parts of hacksaw are - Frame and Blade.
1. Hacksaw Frame
o Hacksaw frame is made of mild steel strip and
conduit pipe.

3. Basic workshop tools
MECH LAB
User | [email protected]
o It is a U shaped metallic solid or tubular frame.
o There is a wing nut for tightening the blade.
Hacksaw frames are of three types
(i) Solid Hacksaw Frame
(ii) Adjustable Hacksaw Frame
(iii) Deep Cutting Hacksaw Frame
I. Solid Hacksaw Frame –
• It is made by bending mild steel strip at right angle.
• Only a blade of a particular standard length can be
fitted to this frame.
II. Adjustable Hacksaw Frame –
• This frame has two parts. The pins placed on them
are used to increase or decrease the length of the
frame.
• Different sized blades like 250 mm or 300 mm are
fitted in it.

4. Basic workshop tools
MECH LAB
User | [email protected]
• Types of adjustable hacksaw frame
o Flat type: -Only a blade of a different standard
length can be fitted to this frame
o Tubular type:
o It is most commonly used type.
o It gives better grip and control while sawing.
III. Deep Cutting Hacksaw Frame - This frame is shaped
like a 'U' alphabet.
• it is used for deep cutting of the jobs.

5. Basic workshop tools
MECH LAB
User | [email protected]

2. Hacksaw Blade

• Hacksaw blade is generally made of high carbon
steel (HCS), high-speed steel (HSS) or low alloy
steel. It is hardened and tampered.
• HCS used for general cutting and HSS for tough
resistant material
• The selection of the blade depends on the shape
and hardness of the material to be cut.

6. Basic workshop tools
MECH LAB
User | [email protected]

Parts of a hacksaw blade
• Back edge
• Side
• Center line
• Pin holes

Specifications of Hacksaw Blade
• Type- Hard or Flexible
• Standard Length – 250 or 300 mm
• Width – 13 to 16 mm
• Thickness – 0.60 to 0.80 mm

7. Basic workshop tools
MECH LAB
User | [email protected]
• Pitch (Gap of teeth) - 0.8 to 1.8 mm
The size of the blade is considered from the center of
one hole to another.
Types of hacksaw blades
I. All hard blade
• Entire length between the pin hole is hardened
• It is used for harder materials such as HCS, die steel
and tool steel
II. Flexible blade
• Only the teeth portion is hardened.
• Because of flexibility these blades are useful for
cutting along the curved lines.
• Flexible blade should be thinner than harder blade.

8. Basic workshop tools
MECH LAB
User | [email protected]
PITCH OF HACKSAW BLADE
• It is the distance between two adjacent teeth

Classification Pitch Use

Fine

0.8 mm
Thin tubes
Sheet metal
Conduit tubes



Medium

1 mm
Angle iron
Brass tubes
Copper
Iron pipe

1.4 mm
Tool steel
High carbon steel
High speed steel


Coarse


1.8 mm
Bronze
Brass
Soft steel
Cast iron
Heavy angle iron

9. Basic workshop tools
MECH LAB
User | [email protected]
SETTING OF HACKSAW TEETH
• Free movement of the blade is achieved by the
setting of the hacksaw teeth.
• It prevents the binding of blade when
penetrating into the material.
There are two types of hacksaw teeth settings,
I. Staggered set
- Alternate teeth or group of teeth are staggered
- This arrangement helps in free cutting & provide
good chip clearance.

10. Basic workshop tools
MECH LAB
User | [email protected]
II. Wave set
- Blades are arranged in wave form.


Type of set

Pitch

Wave set

0.8 mm

Wave or staggered

1 mm

Staggered

Over 1 mm