ड्रिलिंग Machine

The necessary steps to make a counter bore

• Clamp work piece
• Make hole of appropriate size
• Fix on chuck right type of counter bore
• Counter bore to the required depth


Drill press

A drill press.A drill press (also known as pedestal drill, pillar drill, or bench drill) is a fixed style of drill that may be mounted on a stand or bolted to the floor or workbench. A drill press consists of a base, column (or pillar), table, spindle (or quill), and drill head, usually driven by an induction motor. The head has a set of handles (usually 3) radiating from a central hub that, when turned, move the spindle and chuck vertically, parallel to the axis of the column. The table can be adjusted vertically and is generally moved by a rack and pinion; however, some older models rely on the operator to lift and reclamp the table in position. The table may also be offset from the spindle's axis and in some cases rotated to a position perpendicular to the column. The size of a drill press is typically measured in terms of swing. Swing is defined as twice the throat distance, which is the distance from the center of the spindle to the closest edge of the pillar. For example, a 16-inch (410 mm) drill press will have an 8-inch (200 mm) throat distance.

A drill press has a number of advantages over a hand-held drill:

less effort is required to apply the drill to the workpiece. The movement of the chuck and spindle is by a lever working on a rack and pinion, which gives the operator considerable mechanical advantage.
the table allows a vise or clamp to position and lock the work in place making the operation much more secure.
the angle of the spindle is fixed in relation to the table, allowing holes to be drilled accurately and repetitively.

DrillSpeed change is achieved by manually moving a belt across a stepped pulley arrangement. Some drill presses add a third stepped pulley to increase the speed range. Modern drill presses can, however, use a variable-speed motor in conjunction with the stepped-pulley system; a few older drill presses, on the other hand, have a sort of traction-based continuously variable transmission for wide ranges of chuck speeds instead, which can be changed while the machine is running.

Drill presses are often used for miscellaneous workshop tasks such as sanding, honing or polishing, by mounting sanding drums, honing wheels and various other rotating accessories in the chuck. This can be dangerous on many presses, where the chuck arbor is held in the spindle purely by the friction of a Morse taper instead of being held securely by a drawbar.


[edit] Geared head drill
The geared head drill is identical to the drill press in most respects, however they are generally of sturdier construction and often have power feed installed on the quill mechanism, and safety interlocks to disengage the feed on overtravel. The most important difference is the drive mechanism between motor and quill is through a gear train (there are no vee belts to tension). This makes these drills suitable for use with larger drill bits.


[edit] Radial arm drill
A radial arm drill is a geared head drill that can be moved away from its column along an arm that is radial from the column. These drills are used for larger work where a geared head drill would be limited by its reach, the arm can swivel around the column so that any point on the surface of the table can be reached without moving the work piece. The size of work that these drills can handle is considerable as the arm can swivel out of the table's area, allowing an overhead crane to place the workpiece on the fixed table. Vises may be used with these machines but the work is typically bolted to the table or a fixture.


[Mill drills are a lighter alternative to a milling machine. They combine a drill press (belt driven) with the X/Y coordinate abilities of the milling machine's table and a locking collet that ensures that the cutting tool will not fall from the spindle when lateral forces are experienced against the bit. Although they are light in construction, they have the advantages of being space-saving and versatile as well as inexpensive, being suitable for light machining that may otherwise not be affordable.



The seven variables that should be considered prior to selecting a cutting
speed for a twist drill
i) Type of work piece ,ii) Type of cutting tool ,iii)Rigidity of machine ,iv)
Rigidity of set up ,v) accuracy required ,vi) surface finish required ,vii) type of cutting fluid

ट्विस्ट Drill

a) The three major parts of a twist drill
• Flute provide rake angle , allow chip to escape ,allow oil to reach work piece.
• The land are narrow ridge along the flute that bears against the wall of hole to prevent sticking
• The lip is the cutting edge.

b Grinding too much clearance on the cutting lips of a twist drill will reduce the strength of twist drill and so the drill bit will easily break