Page 19 - CITS - Fitter Trade Practical - Volume -2

FITTER - CITS

Skill Filing radius (external)

Objectives: At the end of this exercise you shall be able to
• file external radius.

Filing radius is entirely a different technique, and needs considerable skill for filing accurately with a good finish.

In this type of filing, the file has to be held perfectly horizontal widthwise, and at the same time a rocking motion
given lengthwise. The surface filed should not have any flat surface and should have a uniform curve. Radius
filing of external surfaces is carried out in different steps
Rough filing of corners
The corners are filed and brought closely to line using a flat bastard file. (Fig 1)

Fig 1

Rounding of corners

The flat surfaces are rounded and brought near about to finishing size, using a flat second cut file. In this, the file
is moved forward across the curve with a turning motion. (Fig 2)

Fig 2

Final finishing of radius
For finishing steps, a smooth file is used. The file is given a see-saw motion along the curved line until the required
radius is formed. (Fig 3)

Fig 3

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CITS : C G & M - Fitter - Exercise 59