CHAPTER 12 STEELWORKER TOOLS AND EQUIPMENT

In the shop and out on a jobsite, you will be using grinders, portable power drills, compressors, saws, and various other tools. As a Steelworker you need to be thoroughly familiar with the operation and maintenance of these tools as well as all applicable safety precautions.

BENCH AND PEDESTAL GRINDERS

The common bench and pedestal grinders are the simplest and most widely used grinding machines. The grinding work done with them is called OFFHAND GRINDING. Offhand grinding is used for work on pieces that can be held in the hands and controlled until ground to the desired shape or size. This work is done when the piece king ground does not require great precision or accuracy.

The bench grinder (fig. 12-1) is attached to a bench or table. The grinding wheels mount directly onto the motor shaft. One wheel is coarse for rough grinding, and the other is fine for finish grinding.

The pedestal grinder, inmost cases, is larger than the bench grinder and is equipped with a base and pedestal fastened to the floor. The DRY TYPE (fig. 12-2) has no arrangement for cooling the work while grinding other than a water container into which the piece can be dipped to cool it. The WET TYPE (fig. 12-3) is equipped with a built-in coolant system that keeps the wheels constantly drenched with fluid. The coolant washes away particles of loose abrasive material, as well as metal, and keeps the piece cool.

Figure 12-1.-The bench grinder, Eye shields have not been mounted.

Figure 12-2.-The pedestal grinder (dry type).

Figure 12-3.-Pedestal grinder (wet type) wttb a built-in coolant system

Bench and pedestal grinders are dangerous if they are not used correctly They must never be used unless fitted with guards and safety glass EYE SHIELDS (fig. 12-4). Even then you must wear goggles or safety glasses. A TOOL REST is furnished to support the work while grinding. It should be adjusted to come within one eighth of an inch from the wheels. This will

Figure 12-4.-Eye shields for bench and pedestal type of grinders.

prevent work from being wedged between the tool rest and the wheel. Turn the wheel by hand after adjusting the tool rest to ensure there is satisfactory clearance completely around the wheel (fig. 12-5).

The grinding wheels themselves can be sources of danger and should be examined frequently, based upon usage, for irregularities and soundness. You can test a new wheel by suspending it on a string or wire and tapping the side of the wheel with a light metal rod. A solid wheel will give off a distinct ringing sound, A wheel that does not give off such a sound must be assumed to be cracked and should be discarded. Under no circumstances should it be used. Since it is not practical to check the wheels by this manner every time you use the grinder, make it a habit never to stand in front of a grinder when it is first turned on. A cracked wheel can disintegrate and become projectiles quickly.

The wheel must also run true and be balanced on the shaft. A WHEEL DRESSER (fig. 12-6) should be used to bring abrasive wheels back to round and

Figure 12-5.-Properly spaced tool rest.

Figure 12-6.-Mechanical wheel dresser.

remove the glaze that occurs after heavy use. This is done by holding the dresser firmly against the wheel with both hands, using the tool rest for support. Then, as the wheel turns, move the dresser back and forth across the surface (fig. 12-7). For maximum efficiency and safety in operating the grinder, you should observe the following rules:

1. Use the face of the wheel, never the sides.

2. Move the work back and forth across the face of the wheel. Even wear results because this action prevents the wheel from becoming grooved.

3. Keep the wheel dressed and the tool rest properly adjusted.

Do not shape soft metals, like aluminum, brass, and copper, that tend to load (clog) the abrasive wheel. These metals should be shaped by other methods, such as tiling, sanding, and chipping.

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