Files

Files

Introduction

File

Files are hand tools used for removing material from the surface of work pieces. The operation is called ‘Filing’. Filing is mostly by Hand, although filing Machines are also Available.

Material of File

To remove material from the work piece with a file, the file must be harder than the work piece. To get required hardness, Files are made out of High Carbon Steel alloyed with a little chromium. They are carefully hardened and tempered, after the teeth are cut.

Specification of Files

Files are specified by the following

a.       Size:

The size of a file is indicated by its length in inches or in cm. commonly used sizes are

·         14” File – 350 mm

·         12” File – 300 mm

·         10” File – 250 mm

·         08” File – 200 mm

·         06” File – 150 mm

·         04” File – 100 mm

b.      Type of Cut:

There are two types of files according to cut

·         Single Cut File: Single cut files are used for filing on soft materials and for use on lathe. It is safer to use single cut file on lathe, because the resultant cutting force tries to drift the file away from the running spindle.

·         Double cut File: Double cut files are used for filing quick removal of stock on steel and to get a smooth flat surface.

c.       Shape:

Types of Files

There are different shapes of files which are used for different purposes.

                                 i.            Flat File: Used for Filing Flat Surfaces

                               ii.            Square file: Used for filing Square and rectangular slots and steps

                              iii.            Triangular files: Used for filing angular surfaces

                             iv.            Round File: Used for filing holes and round corners.

                               v.            Half round Files: Used for Filing Internal radii (fillers) and Round Surfaces

                             vi.            Knife edge file: Used for filing Narrow angular teeth

                            vii.            Rasp file: This is a coarse teeth file for filing on very soft materials like wood, horn, plastic etc.

Rasp Files

Needle Files

                          viii.            Safe edge File: This is an ordinary flat square or triangular file are ground off to make it a safe side which is at right angles to it is not spoiled.

                             ix.            Needle file: These are a set of thin files of different shapes; they are used for fine work. They are also called as ‘Jewellery Files’ because they are used by jewelers in making of jewellery.

                               x.            Machine Files: The difference between hand files and machine files is that these are made with a square tang for holding in the machine. They are also not tapered.

d.         d,   Grade:

The grade of file indicates its roughness or smoothness and depends on the both of teeth per inch or centimetre. Accordingly, they are named as Rough, Bastard, Second cut, Smooth and Dead Smooth. Rough files are used for removing material quickly while smooth files are used for obtaining a smooth surface.

The grade of the file is specified by the no. of the teeth in 1cm along the file axis. Accordingly , these files a named as Rough files, Medium Files(Second Cut), Fine Files(Smooth Files), Extremely fine files(Dead smooth Files).

File Length in mm	100	150	200	250	300	350
No. of teeth on Rough per cm	18	15	10	9	8	7
No. of teeth on Second Cut per cm	21	17	15	14	13	12
No. of Teeth on Smooth per cm	30	20	19	18	16	16
No. of Teeth on Dead Smooth per cm	34	30	25	24	22	22

Filing Methods

The different Filing Methods are

1.     Straight Filing

In this Method the file is held Right angles to the surface and moved straight which causes the material to cut. Generally, Backward Stroke is Idle Stroke. This method is used mostly for soft surfaces.

2.     Cross Filing

In this method the file is held approximately at 60% to the surface and filing is done alternately from left to right. Cross Filing is used to remove material quickly and to get flat surface.

3.     Draw Filing

In this method the file is placed at right angles to the surface. The left hand is placed on the handle and the right hand on the tip and held by the thumb and the finger, using both hands the file is drawn across the surface. This method produces a smooth and flat surface by removing very little material and mostly used with thin pieces.

Cleaning

During filing, work material gets clogged in between the file teeth. In that condition the file will not cut and slips away. The file is cleaned by using a file brush or file spattle. Is made up of brass or Aluminium trip of about 2 to 2.5 mm thick, the file brush is made out of steel wires and wooden handle. The file brush should not be used for cleaning smooth files.

Rules for Filing

                     i.            Use full length of the file but not to the extent that the handle hit against the work piece or vice.

                   ii.            The file cuts in the forward stroke only, the backward stroke is idle stroke, Therefore the forward stroke must be slow and with pressure and the backward stroke must be fast without pressure.

                  iii.            Do not use file as a hammer or as a Lever.

                 iv.            Do not put too much pressure on smooth files and Needle files.

                   v.            Use correct piece of the file for the work piece.

                 vi.            Never use files without handles or broken handles.

                vii.            Whenever possible use new files on brass, copper etc. Old files will not work against these materials.

              viii.            We use old files first on cast iron and then new file because the skin of cast iron is hard and a new file will become blunt quickly if used.

                 ix.            After filing lead wash your hands thoroughly with soap because lead is a poisonous metal.