6th May 2020, Period 7, Class 12, Engineering Graphics, Machine Parts - Washer

Dear Students,

Good Morning and a warm welcome to today's class.

It feels really nice to meet up for yet another class this morning.

Recall that in our last class, we had learnt about a Hook (or J) bolt 

Let us now proceed further and learn about the Washer and also draw its projections.

Washer

A washer is a circular machine part that is used to tighten a nut on the bolt. It also holds the nut tightly on the parts that are required to the joint together. Refer Fig 1. A washer has a circular hole at its centre through which the shank of the bolt passes. Refer Fig 2 below. 

A washer is of two types.

1. Plain Washer
2. Spring Washer

We will study only about a plain Washer. It is shown in Fig 1 below.


Fig 1: A plain washer



Fig 2: A Bolt Nut and Washer assembly


The specification of the washer is mentioned in terms of the nominal diameter of the bolt on which it is to be used. If 'd' is the nominal diameter of the bolt (for example 25 mm) then the relevant dimensions are as below

d	d+1	2d+3	d/8
25	26	53	3

1). d+1 = inner diameter (ID) of washer
1). 2d +3 =  Outer diameter (OD) of the washer
2). d/8  =  Thickness, t of the washer




Front view                  LH Side View



Exercise - Washer


Q 1. Draw to scale 1:1, the front view and the top view of a washer, taking the nominal diameter of the bolt as 25 mm keeping the circular face of the washer parallel to the VP.




Exercise