Electricity provides a major hazard to safety of a drill rig. Batteries require:
* servicing by a addition of water (unless "maintenance free").
* maintenance: checking charge, recharging as necessary, cleaning and oiling terminals, tightening terminals.
Generators and Alternators require maintenance: keep clean and re place worn brushes. The bearings in generators and alternators are usually sealed. They are lubricated for life at the time of manufacture. Don't attempt to oil these. In any case, avoid overoiling any bearing in an electrical compo¬nent.

The wire rope diameter must suit the groove in the sheave. Always use a sheave with a diameter at least 20 times the wire rope diameter. However, when using not-rotating wire rope, use a sheave 17 times the wire rope diameter. These rules also apply to drum diameter. The wire rope must be under tension when wound on to the drum. I he first layer must be coiled tightly.

WIRE ROPE CLIPS

Clips must be correctly fitted with the saddle on the “live wire. This is to avoid the” cutting effect of the bolt which reduces the strength of the table.

WHERE CAN YOU FIND THIS INFORMATION

Bit selection will be considered in detail in Chapter 7. The main types of bits available to rotary drillers are:
* blade bits,
* roller bits,
* hammer bits,
* diamond bits.
Special purpose bits are available:
* coring bits,
* pilot bits,
* reaming bits.
Blade and drag bits: These are used in unconsolidated formations and soft rocks and cut using a shearing action.
Drag bits have 3 or 4 cutting wings tipped with carbide inserts and usually an A.P.1. regular threaded pin connection. Blade bits have a similar cutting action, except that the blades can be replaced

SECTION 1 MEASUREMENT CALCULATIONS
• The metric system and its use
• Length – the metre
• Area – The square metre
• Volume – The cubic metre
Mathematics may a driller first love, however an understanding and mastery of the basic principles involved is necessary for drillers to be able to carry out their darly task.
This sections is designed minimum of confusion or doubt. Matheatical formulae have been simplified wherever possible and examples relate to practical field conditions.
THE METRIC SYSTEM AND ITS USE

The water hammer you sometimes experience when you turn off a tap stems from extreme hydraulic shock. The hydraulic shock is brought about by sudden pressure changes in the liquid and these are transmitted throughout the liquid. Pulse dampers are usually used to even out the pressure pulses and make the discharge more even. Liquids do not compress (for all practical purposes).

Contributing properties
Cooling means carrying heat away. Almost any fluid moving over the bit will do this. Water does it best. Water is helped by a "wetting" agent that keeps the bit surfaces clean and wet.

Bottom clearing is most effective when:
1. low bottom hole pressures exist.
2. fluid has low viscosity.
3. fluid has high velocity.
4. fluid is free of solids.
Once clear of the bottom, the chips should be held, and even when the velocity of the clearing fluid drops, the chips should be held suspended.
Factors that inhibit bit cooling and bottom hole clearing

The maintenance activities described in the engine section will reduce the likelihood of engine problems, but if they occur, a driller must be able to get the vehicle going. The possible causes for a number of engine problems are listed below.
Difficult starting
Petrol (gasoline) engines
* lack of fuel or ignition switch off
* weak or faulty battery or starter
* dirty or burnt points or plugs
* low compression (leaking valve)
* carburettor/injectors flooded
* moisture on high tension wires or inside distributor
* dirt or water in fuel

Adequate records should be maintained on each drill and other major pieces of machinery to show when repairs or replacements occurred. Over a period of time the records will indicate which components are being repaired or replaced more often than is normally expected. This then enables the particular problem areas to be corrected.
Rig safety care and housekeeping
An important part of rig mechanics, is the care and protection of safety equipment.
Housekeeping: Rig cleanliness and tidiness provide many benefits.
* Wear or damage is readily detected.

The air line supplying portable air tools should be equipped with an air filter and an air line lubricator. Check that the air pressure is correct and that the hoses are adequate to carry the volume of air required.
Some air tools require daily flushing to clean the tool and daily additions of oil to the tool itself.
The "quick connector" fitted to some air tools is sealed by an "O" ring which must be replaced if a leak developes. Compressed air is always dangerous even through a small hose. Keep air jets away from the body.
Pointers on the use of power tools

We have talked about the basic unit of mass as the kg. The basic unit of force is the Newton and the size of the force may be stated in newtons. Every object is pulled to the earth by a force called gravity.
On carth a 1 kg mass is pulled down by a force of approximately 10 newtons. The force gravity on 1 kg mass is equal to 10 newtons. If a person hava a massol of 75 kg a force of 750 newtons is exerted on that mass at the surface of the earth.

PRESSURE

Pressure is the force exerted over an area of contact:

Used for:
* Holes for cast in-situ foundation piers
* Mineral sampling
* Access holes
Advantages:
* Produces clean dry holes
* Drills large diameter holes.
Disadvantages:
* Water in hole washes cutting from the auger flights
Bucket augers have similar applications to those of the short flight augers.
Advantages:
* Drills larger holes
* Undetcuts casing
* Drills below water and operates in mud filled holes
* Large rotary drive provides torque to drill harder materials
Disadvantage:
* Depth capacity is limited

The table tool spudding machine is capable of handling many drilling applications. The technique used must be adjusted to suit The purpose of drilling. Many techniques have been developed. Here we look at The more common techniques.

Normal table tool operations (consolidated formations): The spudding action is operated to:

* allow The tools to drop freely,
* catch The tools before the bottom so that when The bit strikes The bottom The table is stretthed,
* quickly accelerate The tools upwards,
* allow The weight to come off The table so that The swivel turns to rotate The bit.

Collection of samples is part of most drilling operations. When setting up the site, the driller must provide the means of collecting accurate samples in keeping with the job objectives.

Sampling from water or mud circulation may require:

* use of screens at hole collar (1)
* collection from a sump (2)
* collection of a "whole sample" (3)
* separation of cuttings using a cyclone (4)

Sampling from augers may require:

* access to material spilling from the auger
* access to materials while still on/in the auger (5)

Sampling from ballets may require:

Drilling wears down the cemented carbide in inserts and buttons. Most of this wear is caused by abrasive action at the sides and bottom of the hole as the drill bit rotates. If nothing is done about this wear, the rate of penetration will drop and the inserts, along with the rest of the drill swing will be subjected to abnormally heavy stresses. For this reason, cemented carbide must be reground at regular intervals to restore its original shape. Different kinds of rock cause different degrees and patterns of wear.