This is a basic method of forming a shallow cut into brick or concrete using an electric driven angle grinder. There are hydraulic and air driven machines, but the normal is 110 volt electric. These machines are fitted with either abrasive wheels or diamond tipped blades, usually running dry. Cutting is restricted to a depth of approx. 3.5" (85-90mm) as blades seldom exceed 225mm dia. (9"). These tools are efficient in brick and un-reinforced concrete but not very successful for cutting steel.
Rotary Percussive Drilling
This is the basic method of drilling construction materials using a hand-held drill and is suitable for most hard un-reinforced materials. It can be used for small diameter holes i.e. for rawlplugs 4mm up to 75mm rock drills and over. In the diamond drilling industry it is normal for all operatives to carry a Kango or Hilti type of 110 volt rotary percussive drill/hammer to enable them to carry out simple cutting and fixing operations i.e. drilling brick or concrete to enable adequate bolting down of drilling plant or track sawing equipment. Also used to break out concrete for removal, as well as forming chases for conduits or pipes.
General Drilling Rigs - Diamond drilling rigs can vary in design but the basic principal is the same. The base plate of the drill stand is secured to the concrete/brick to be drilled either by rawlbolt, acrow prop, vacuum pad or weights.
The power unit is either electric, hydraulic or air. Drilling bits start at 10mm and can go to as large as 1 metre or more. Drilling depths are virtually unlimited using barrel extensions.
The smaller the diameter, the greater the speed of rotation, and except for a few special types, all have a water feed through the driving shaft, to keep the diamonds cool, the cutting free of grit, and generally assist in reducing wear. Water also totally eliminates dust.
This technique is used when precise circular cuts are needed, to create openings for example, for plumbing, electrical and heating/ventilation installations. Core drilling is commonly used to create the holes for routing cables or for placing anchor bolts, for installing load carrying devices or for concrete sample analysis.
A core drill bit consists of a steel tube with diamond segments brazed or welded on the drilling end, and mounted on a rotating shaft. Core drill machines can be operated in either vertical or horizontal direction and can be powered by electric, hydraulic or air sources.
Trailer Rigs - A drill rig unit can also be fitted to a mobile two-wheel trailer to form a specialist trailer drilling rig capable of being towed behind a van or car. These drilling rigs are used for specialist operations such as core sampling and installation of motorway barriers etc.
This equipment was developed to enable cutting of door and window openings through walls as well as through floors for stairways, lifts, etc., without the need to stitch drill i.e. a series of interlocking holes.
The track saw consists of an aluminium rail which has a set of supporting feet that are secured to the concrete by means of rawlbolts or similar. This track has guides or rails built into it together with a toothed rack or track.
The travelling bogey is secured to track by runners and a cog wheel engages the ‘rack’ to enable it to travel backwards and forwards along the track. The bogey also houses the hydraulic motor which powers the diamond saw blade. This can be as small as 450mm dia. to as large as 2m or more. The smaller the diameter the faster the r.p.m. and vice-versa.
The power unit is now-a-days always hydraulic - either electric or diesel powered, and is operated by remote control away from the surface being worked upon.
The cutting is carried out by making a series of passes along the length being cut. The depth of each pass depends upon the type of material, the blade and the operative.
The operator starts with a small diameter blade and works upwards to finish with one suitable to complete the job. It is vital to ensure that all sections being cut or worked upon are adequately supported, and all services made safe.
This is a relatively recent development. Although there are some wire saws which were purpose made, the machines now generally in use in the building industry to-day can be quickly and easily converted from wall/track saws into wire saws.
The method of setting up is similar to that of the track saw but in lieu of the saw blade a grooved pulley wheel of 800mm diameter is fitted which takes the diamond wire. This wire is passed over any number of small idler pulleys to the surface being cut. The wire is a steel core of strands approx. 6m. dia. of almost any length. It has diamond beads along its length approximately 30mm apart and 10mm dia. The beads are separated by either small springs, plastic or rubber, depending upon the type of wire and the manufacturer.
The wire is positioned over the pulleys and fed through pre-drilled holes in the concrete that is being cut and back over the drive pulley. The wire can be of almost any length and is joined by special crimps.
Sawing is carried out by turning on the power and maintaining a constant speed, whilst applying pressure on the wire by gently applying a steady backward movement along the track.
This is a development of the wood chain saw and is again hydraulically powered. It employs a chain fitted with diamond segments.
It has not proved to be very successful in reinforced concrete especially in Thames Valley flint.
It is very useful for cutting window and doorway openings in brick and block because straight lines can be cut with right angle comers, but much work needs to be done on the chain life before it can be a total success in concrete. This machine must always have a water supply.
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