Page 139 - CITS - ED - Mechanical

ENGINEERING DRAWING - CITS

Screws

Grub screws are comparatively smaller in dia and short in length. They are made of hardened steel,used for holding
two parts in position eg., a collar pulley, or gear on a shaft.
On driving it into position, it produces a clamping force, resists relative motion between the assembled parts. The
grub screws are fully cylindrical , on one end they are provided with hexagonal socket or screw driver slot. On the
other end they are formed into different points. (Fig 1)
Hexagonal socket grub screws or screw driver slot are of following types.IS: 6094 (Fig 1)
They are namely as follows:

– Flat point (FP)
– Cone point (TP)
– Full dog point (FDP)
– Half dog point (HDP)
– Cup point (CP)

– Conical point
These are designated by the shape of their ends. These are available in sizes M3, M4, M5, M6, M8, M10, M12,
M16, M20, M 24, Max. length 60 mm. These are operated by using hex. bent key (Allen key).

Slotted grub screws as per IS:2388 are designated by letters. (Fig 2)

Fig 1 Fig 2

– Type A - Flat end
– Type C - Conical end

– Type E - Cylindrical dog point
– Type G - Tapered dog point
– Type J - Cup point
– Type K - Oval point
Set screws (Not as per BIS)::These screws are operated by screw drivers or a spanner. They are available in
different sizes M1 to M24. The lengths vary according to dia.
Function of a set screw is same as that of grub screw. The set screw has different form of head (i) cup or round
head (ii) square head (iii) cylindrical or cheese head (iv) filister head (v) counter sunk head (vi) rounded counter
sunk head (vii) square head with collar. Fig 3 shows the above screws.
Screws are specified by designating the head, diameter; length and IS:No and property class.

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CITS :Engineering Drawing (Mechanical) - Exercise 8