Turning a Mild Steel Bar

2186 Words5 Pages

TASK: Turning a Mild Steel Bar.We were each given a mild steel bar to

work into the shape shown in the drawing found on the following pages,

TURNING

TASK: Turning a Mild Steel Bar.

We were each given a mild steel bar to work into the shape shown in

the drawing found on the following pages, to do this we used the

Turning Lathe in the workshop, but before we could start some

measurements had to be taken. This meant using a micrometer to

determine the diameter of the bar to begin with.

A micrometer allows a measurement of the size of a body. It is an

extremely accurate piece of apparatus. The Thimble is rotated, causing

it to move right or left. It is connected to the right-hand Measuring

Rod. The measured size of the mild steel bar is the distance between

the two measuring rods when they are just in contact with the sides of

the bar.

Because of the mechanical advantage due to the fine pitch of the screw

threads that move the thimble and the right-hand measuring rod, it is

easy to use enough force in closing the rods on the object being

measured to deform either the rods or the object. A Friction Screw is

used, which applies just enough torque to rotate the thimble so it

doesn’t deform the bar or the measuring rod. This Friction Screw is

found at the end of the thimble.

The reading of the micrometer is outlined in the diagram found on the

following pages of this document.

The First part of the task was to give one end of the bar a smooth

finish, this was done by fixing the bar into the lathe using the chuck

key, then positioning the tool piece as near to the centre of the bar

as possible then shaping off a small amount of material, it is

important to get the tool piece in the correct position as if it is

too high or too low it will miss part of the material. A Cutting speed

was determined by the diameter and material of the bar then equating

this figure to one of the speeds attainable by the lathe. This turned

out to be 370 RPM for this machine selecting the relevant gears.

As the diameter of the bar reduces, the cutting speed will need to

increase.

Once one end has been smoothed, the bar was turned round and worked on

from the other end, the first task was to remove 75mm in length with a

resulting diameter of 22mm, this was done not all in one go as you had

Open Document