British Columbia Carpenter Apprenticeship Program

British Columbia Carpenter Apprenticeship Program Level 2 Line C Competency C-2 Use Portable Power Tools 7960003550

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Competency C-2 Use Portable Power Tools Contents Objectives...2 Learning Task 1: Use Hammer Drills, Rotary Hammers and Demolition Hammers...3 Learning Task 1: Self-Test...12 Learning Task 2: Use Angle Grinders...13 Learning Task 2: Self-Test...16 Learning Task 3: Describe the Use of Power Trowels...17 Learning Task 3: Self-Test...22 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 1

Competency C-2 Use Portable Power Tools Carpenters use concrete tools such as hammer drills, rotary hammers, demolition hammers, angle grinders and power trowels when working with concrete. This Competency introduces these tools and describes some of the tasks that can be accomplished with them. Objectives When you have completed the Learning Tasks in this Competency, you will be able to: use a rotary hammer to drill and set anchors in concrete use an angle grinder to smooth surfaces and cut concrete use a demolition hammer to chip concrete describe the use of power trowels Competencies Written: Describe Concrete Drilling, Grinding and Finishing Tools You will be tested on your knowledge of concrete tool terminology, basic operating techniques and safety concerns associated with concrete tools. Practical: You will use a rotary hammer to drill and set anchors in concrete, you will use a demolition hammer to chip concrete and you will use an angle grinder to smooth and cut concrete. 2 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 1 Learning Task 1 Use Hammer Drills, Rotary Hammers and Demolition Hammers Concrete drills and hammers are used to make holes in concrete and masonry or to chip away concrete during demolition. There are a wide variety of products on the market today to accomplish these tasks and they are known by many different names. However, all may be categorized in three major groups: hammer drills, rotary hammers and demolition hammers. Hammer Drill Hammer drills work much like an ordinary drill except that a mechanical action makes the bit vibrate (hammer) into the concrete. Hammer drills are capable of drilling up to 20 mm ( ) diameter holes. The hammer drill is used to drill small diameter holes up to 20 mm ( ) in concrete using the hammer mode. A rotary only mode is used to drill holes in steel and wood. Figure 1. Hammer drills use ratchet teeth to provide forward thrust Rotary Hammer The hammering action of the rotary hammer is delivered by a piston-like device. The rotary hammer s mechanism delivers a blow about 10 times harder than a hammer drill. A rotary hammer will handle most drilling jobs. It may also be used for light chiseling and demolition work. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 3

Learning Task 1 Competency C-2 Like the hammer drill, it has a switch that allows it to be used in several different modes. These will include hammer only and rotary hammer, and may also include rotary only for using coring bits. The most common mode selections are the hammer only and the rotary hammer. This combination makes this hammer ideal for setting an anchor, because the rotary hammer mode can be used for drilling the hole and the hammer-only mode can then be used for setting the anchor. Figure 2. Rotary hammer used for setting anchors in a foundation Using the Rotary Hammer Mode Rotary hammers, depending on size, can drill up to 50 mm (2 ) diameter holes. Most hammer drills and rotary hammer drills are equipped with a switch that allows them to operate in either the rotary only mode or the rotary hammer mode. The rotary hammer mode is used for concrete and the rotary only mode is used for most other materials. Never use the rotary hammer mode when drilling into wood or steel, or the work may be damaged by the hammering action of the drill. 4 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 1 Pushing harder will not make a rotary hammer drill any faster. In fact, the rotary hammer works best when only moderate pressure is applied (Figure 2). Applying only light pressure may cause the bit to bounce and damage it. The depth of the hole is critical when drilling in for anchors. Use the depth gauge to ensure the depth is exactly as specified by the manufacturer (Figure 3). Figure 3. Depth gauge Drilling Large Diameter Holes in Concrete Using a large drill or rotary hammer in drill-only mode, a core bit can be used to drill large diameter holes from 50 mm to 150 mm (2 to 6 ). A core bit is a hollow, cylindrical drill bit that is closed at one end and has a series of cutting teeth at the open end. The cutting teeth are usually impregnated with industrial diamonds. This bit is not used with a hammer action. A steady stream of water is used to cool and clear away the concrete from the drill bit. The holes are used to run pipes or install drains. They can also be used to take a core of concrete from an erected structure for testing purposes. For larger holes or better control, a specialized rig-mounted coring drill (Figure 4) is used. It is normally mounted on a wheeled stand and is equipped with a soft start, clutch, and water feed. This type of machine can drill up to 350 mm (14 ) diameter holes in concrete. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 5

Learning Task 1 Competency C-2 Figure 4. Rig mounted core drilling machine Demolition Hammers Demolition hammers (Figure 5) are larger and heavier than hammer drills and rotary hammers. They are sometimes referred to as breakers or jack hammers. Unlike the smaller drilling tools, they work in hammering mode only. Larger demolition hammers are powered by compressed air. Carpenters usually use the smaller, electrically powered units. Uses Demolition hammers are used for chipping and demolishing concrete. When equipped with special bits or attachments, they may also be used for special tasks such as tamping or scaling. Using a Demolition Hammer Use the shortest bit that is practical for the job. Long bits tend to bend and absorb some of the blow energy. Make sure that the bit is sharp before you start work. 6 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 1 When working with a demolition hammer, start the bit near the edge of the block or wall and angle it toward the edge (Figure 6). Allow the weight of the hammer to assist in the breaking action. Figure 5. Chipping with a demolition hammer Figure 6. Work toward the edge BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 7

Learning Task 1 Competency C-2 Bits and Accessories A wide variety of bits and accessories are available for concrete drills and hammers. These range from ordinary wood-drill bits to the specialized digging attachments used with demolition hammers. Some common bits and accessories are illustrated in Figure 7. Figure 7. Bits and accessories 8 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 1 Bull Point A bull point is an attachment that comes to a sharp point and is used for breaking up concrete or other hard material. It is used when the material is too hard for a chisel bit. Bull points are used mainly with demolition hammers, but may also be used with rotary hammers for light demolition work. Chisel Chisels are also used for breaking concrete and other hard material. They are available for either demolition hammers or rotary hammers. The cutting edge of a chisel is wider than a bull point. This allows it to take a bigger bite. However, the wider blade gives the chisel less impact than a bull point. Chisels may also be used to cut a groove in concrete. A concrete saw is used to cut the edges of the groove, and a demolition hammer with a chisel bit is used to remove the concrete from between the saw cuts. Scaling or Wide Chisel A scaling or wide chisel is quite similar to an ordinary chisel except that it has a wider blade. It is used for a variety of scaling operations such as removing tile or ornamental brick and cleaning concrete splatter from walls. Digger A digger has a slightly wider blade than a chisel and is used for a variety of digging and trenching jobs. Spade A spade has a wide, shovel-shaped end, and is used with a demolition hammer for digging in softer materials such as hard-packed soil or clay. Asphalt Cutter An asphalt cutter is used with a demolition hammer when removing asphalt. The wide cutting edge allows the operator to make a long straight cut around the perimeter of the area to be removed. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 9

Learning Task 1 Competency C-2 Tamping Tool A tamping tool is used with a demolition hammer to pack down soil or loose gravel. It is used in small areas, such as for tamping around a column or along the edge of a wall. Other equipment is used for tamping large areas. Bushing Tool A bushing tool is an attachment used with a demolition hammer to make decorative patterns on a concrete wall. Concrete that is finished with a bushing tool has the appearance of exposed aggregate. Blow-out Bulb A blow-out bulb and round brush are used to clean out holes before inserting anchors. Do not blow out the drilled hole by blowing into it. The dust from drilling concrete is extremely fine and should not be inhaled. Carbide Bits Always use steel bits with carbide tips when drilling into concrete with a hammer drill or a rotary hammer. Carbide-tipped bits are extremely hard and are designed to stand up to concrete. Helix-shaped bits are designed specifically for concrete. The helix shape removes the maximum amount of debris and helps to prevent the drill from binding in the hole. The carbide tips are extremely hard but they are also very brittle. Never try to straighten a bent bit in a hole or to use the drill like a lever because the tip of the bit will chip and may break off. Carbide tipped bits are very expensive to replace. Handle carbide tipped bits with care. Do not allow them to drop onto hard surfaces. Store them in separate spaces to keep the tips from hitting together. 10 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 1 Concrete Cutting There are a variety of tools available for cutting concrete. A handheld circular saw with a diamond-impregnated blade is capable of cutting a shallow control joint in concrete. Handheld and wheel-mounted concrete saws are available for more demanding jobs. Both types use diamond-impregnated blades. Water is typically used to cool blades and aid in clearing the debris from the cut. Water also helps to control the dust generated from the cutting. Figure 8. Concrete cutting tools Now complete Learning Task 1 Self-Test. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 11

Learning Task 1 Competency C-2 Learning Task 1 Self-Test 1. Identify each of the bits and accessories shown in Figure 1. Figure 1. Bits and accessories 2. What precautions should be taken when handling carbide tipped bits? 3. How is a cut started when using a demolition hammer? 12 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 2 Learning Task 2 Use Angle Grinders Angle grinders are used to smooth concrete surfaces and to cut off exposed reinforcing steel and bolts. Angle grinders are sized by their maximum wheel size, which typically is 4.5 to 7 in diameter. Angle Grinders An angle grinder (Figure 1) is similar in operation to a portable disk sander and can be used for a wide variety of grinding tasks on the job site. Some typical tasks for which angle grinders are used include grinding down high spots in a concrete floor to allow the placement of machinery, grinding down the front edge of steps to prevent water from accumulating, preparing metal for painting, removing concrete splatter from walls and many other grinding jobs. With the proper wheel type, it can also be used to cut steel, such as reinforcing bar and other metals. Types of Wheels It is important not to try using a concrete (masonry) wheel to grind steel or to use a metal wheel to grind concrete. Metal Grinding There are three types of metal-grinding/cutting wheels (disks) used with angle grinders: ferrous metal wheels (cast-iron, steel) non-ferrous metal wheels (brass, copper, aluminum) cut-off wheels (zip disks) The type to use depends on the material to be ground or cut. Concrete Grinding There are different types of wheels for grinding/cutting concrete: wheels for cutting masonry, stucco and plaster concrete grinding wheels abrasive cup wheels BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 13

Learning Task 2 Competency C-2 The main advantage of a cup is that it tends to produce a smoother, flatter finish than other attachments because it only contacts the work on the outer edges (Figure 2). Abrasive cups are used to grind large, open surfaces such as walls or floors. Figure 1. Angle grinder Figure 2. Grinding attachments Wire Wheels and Cups Wire wheels and cups are available for use with angle grinders. They are used for cleaning irregularly shaped objects and to prepare metal for painting. They can be used in confined spaces, corners and other areas where it is difficult to reach with an abrasive cup. Wire wheels and cups can also be used in electric drills. 14 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 2 Figure 3. Wire wheels and cups Safety Precautions An angle grinder can be a dangerous tool if it is not operated with care. Observe the following precautions when using one: 1. The RPM rating of the wheel or cup MUST be greater than that of the angle grinder. 2. Do not use a damaged or worn wheel. 3. Cutting wheels can break and fly apart while you are grinding. Make sure all guards are in place and properly adjusted to protect the user. Safe work procedures should ensure that wherever a safer alternative cutting tool is available or can be obtained, an angle grinder should not be used as a cutting tool. 4. Clear the area of other workers while grinding. 5. The weight and torque of the grinding disk will tend to make the angle grinder turn in your hands when it is started. Keep a firm grip on the tool. 6. Be aware of the sparks and hot filings being discharged from the grinder. They could land on combustible material and start a fire, or cause serious damage to other types of material. 7. Wear appropriate clothing, including goggles or a face shield, dust mask, hard hat, steel toed boots, ear protectors and gloves. Now complete Learning Task 2 Self-Test. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 15

Learning Task 2 Competency C-2 Learning Task 2 Self-Test 1. List four uses for an angle grinder. 2. What is the advantage of using an abrasive cup on an angle grinder? 3. In which situations are wire attachments used on an angle grinder? 4. List the safety precautions that must be followed when using an angle grinder. 16 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 3 Learning Task 3 Describe the Use of Power Trowels Power Trowels Power trowels are used for finishing concrete slabs. A four-bladed trowel is most common. The blades rotate in a clockwise direction when looking down on the trowel. Figure 1. Typical power trowel Walk Behind Power Trowels The size of a power trowel is determined by the diameter of the circle that the blades make. Walk behind power trowels range from 24 up to 48 diameter. 24 trowels are mainly used for finishing in tight areas. Riding Power Trowels For very large projects, two or three separate trowels are assembled into one unit. The operator of these large machines rides on top, and is able to control the movement and rake of the blades. The size of the pass covered by a riding power trowel can range upwards from about 1.5 m (60 ). BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 17

Learning Task 3 Competency C-2 Figure 2. Float blade Blades There are two basic types of blades: floats and trowel blades. Floats Floats are used for final leveling of the concrete surface. Floats are wider than trowel blades typically about 250 mm (10 ) wide. They are made from a thicker gauge of steel and have rounded edges. The size of the float blade can be seen in Figure 2. The float blades slip onto the regular trowel blades. The blades are kept quite flat for the initial floating, which can begin when stepping on the slab leaves a footprint indentation of about 3 mm ( ). The trowel is run at ½ to ¾ speed. Each pass overlaps the last by half the width of the trowel. A second pass is made at 90 degrees to the first and is called a crossover floating. For this pass, the blades are tilted slightly and the engine is run at ¾ speed. Crossover floating allows the finisher to reach areas that were hard to access when travelling the first direction and helps level the slab. Trowel Blades Trowel blades are very similar to the blade of a hand trowel and are typically 200 mm (8 ) wide. They are made from thin steel and are narrow and long. For each pass, the blades are tilted at a sharper angle. The trowel is run at full speed. Each pass will increase the density of the slab surface. With enough passes, the operator can burnish the surface to a mirror-like finish. 18 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 3 Using Power Trowels Power trowels are simple to use and can produce a smooth and level surface as long as a few precautions are followed: 1. Make sure that the concrete is placed and leveled properly. The surface should be very flat before using a power trowel. 2. The concrete should support foot pressure before beginning to use a power trowel. 3. Do not begin any finishing of a concrete slab before the bleed water has evaporated. 4. Move the power trowel over the entire surface of the slab in a uniform manner. Try to cover the surface in a pattern that leaves no distinguishable marks. 5. Allow the concrete to harden between passes with the trowel. The amount of time between passes will depend upon the properties of the concrete and the weather. Starting a Power Trowel Most power trowels are operated by a worker who walks over the surface of the concrete slab with the blades of the trowel spinning in front of the operator. The worker holds handles, which are like those of a bicycle. There is a throttle to control the speed of the spinning blade, and a blade angle adjustment to change the blade angle in relation to the concrete. Place the trowel onto the concrete surface and start the engine. Power trowels use a gasoline engine for power. Start the engine with the throttle set to the low end of the range. As the throttle is increased, the clutch will start to drive the blades. The trowel does not stay stationary, and the operator must not let go of the handles while the trowel is running. Lateral Movement Once running, lifting up on the handles or pressing down on the handles controls the lateral movement of the trowel. Because of the clockwise movement of the blades, the trowel will move to the left if the handles are raised, and will move to the right if the handles are pressed down. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 19

Learning Task 3 Competency C-2 Blade Adjustment The angle of the blades can be adjusted by turning the blade adjustment knob (Figure 3). Turning the knob clockwise steepens the angle, and counter-clockwise lessens the angle. Float blades are used first to level any high spots in the concrete surface. The float blades are usually used with the blade angle set low, or almost parallel to the concrete surface. Trowel blades are used for finishing. For the first pass with these blades, the angle is relatively low. On the second pass the angle is made steeper, applying more pressure to the concrete s surface. Figure 3. Blade angle adjustment On the final pass with the trowel blades, the angle is made quite steep. This will produce a very hard and dense surface that will resist wear. Power trowels can produce an extremely smooth and slippery surface. This surface may not be suitable for some types of pedestrian or vehicle traffic. 20 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2

Competency C-2 Learning Task 3 Maintenance When working with any tools that come in contact with concrete, it is very important to clean the tool immediately after using it. Washing the blades of the power trowel between passes will help keep the trowel clean. Follow the typical maintenance procedures for gasoline engines. Crankcase Oil Always check that there is oil in the crankcase before starting the engine (Figure 4). Figure 4. Crankcase oil filling sprout Use clean gas and if the engine is a 2-cycle engine, use the proper oil to gas ratio. Now complete Learning Task 3 Self-Test. BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2 21

Learning Task 3 Competency C-2 Learning Task 3 Self-Test 1. List five procedures used when finishing a concrete slab with a power trowel. 2. How is the movement of a power trowel controlled? 3. What is a burnished surface? 4. What are two different types of blades used with power trowels? 22 BC CARPENTER APPRENTICESHIP PROGRAM LEVEL 2