The preferred way to control hazards is through engineering or work practice controls. When these controls are not possible or do not provide adequate protection, personal protective equipment (PPE) must be provided as a supplement. Employers must institute all feasible engineering and work practice controls to eliminate or reduce hazards before using PPE to protect employees.

Router Operator Killed by Flying Tool A 32-year-old experienced woodworker was fatally injured at work while operating an overarm router. The worker was making custom rosettes when a steel tool knife was propelled from the rosette cutter. The knife penetrated a Plexiglas shield, and then penetrated and exited his chest. The knife ricocheted off a wall before landing. The knife, measuring approximately 1 5/8 inches square, was part of a cutter-head assembly that had been previously used on a drill press at much lower cutting speeds. It was custom designed for the drill press, not for the router, which is run at much higher speeds. The knife was held in the cutter head by flat shims and set screws; the screws could not counteract the centrifugal forces generated by the high-speed rotation. Fatality Investigation Report 2:2, February 1997, Occupational Health Surveillance Program, Massachusetts Department of Public Health.

Engineering controls involve physically changing the machine or work environment to prevent employee exposure to the potential hazard. Examples are using a guard on a machine, or using local exhaust ventilation to remove dust and other contaminants at the source.

Work practice controls involve removing your employees from exposure to the potential hazard by changing the way they do their jobs. For example, workers should always use push sticks to guide short or narrow pieces of stock through saws. Using a push stick allows saw operators to keep their hands at a safe distance from the saw blades. (See Figure 3.)


Figure 3. Push Stick Work Practice Control

Personal protective equipment encompasses a wide variety of devices and garments designed to protect workers from injuries. Examples include respirators, goggles, safety shields, hard hats, gloves, earmuffs, and earplugs.

What Engineering Controls Are Available to Help Protect My Employees from Machine Hazards?

Machine Guarding

Guards are now standard equipment on most woodworking machines. If you purchase a machine that does not come equipped with a guard, install one. Contact the manufacturer of the machine to see if appropriate guard(s) are available for the equipment. If not, use this guide to help you determine the appropriate guard to install. Because woodworking equipment is dangerous, guards should always be designed and installed by technically competent and qualified persons. In addition, it is always a good idea to have the equipment manufacturer review proposed guard designs to ensure that the guard will adequately protect employees and allow safe operation of the equipment.

There are many ways to guard machines. The type of operation, size or shape of stock, work being performed on the material, method of handling, and production requirements are some of the factors that help determine the appropriate safeguarding method for an individual machine. All moving machine parts that may cause injury must be safeguarded. This includes the point of operation, the power transmission apparatus, and rotary or reciprocating parts. Table 2 describes three types of machine guards commonly used on woodworking machinery: fixed, adjustable, and self-adjusting.

To be effective, a guard should prevent employees from contacting the dangerous parts of the machines, and it should be secure. This is not always possible, as in the case of the radial arm saw. Regardless, workers should not be able to easily bypass, remove, or otherwise tamper with the guard. In protecting the worker, however, the guard must not create additional hazards, nor prevent the worker from performing the job.

Make sure that guards are in working order and that they are appropriate and practical for the machinery. Guards must have adequate strength to resist blows and strains and should be constructed to protect operators from flying splinters and machine parts such as broken saw teeth, cutting heads, and tools.

For more information on methods of machine guarding (including construction of guards), consult Appendix A of this guide. The section "Specific Woodworking Equipment Hazards and Controls" provides more detailed information on guard types for specific woodworking machines.

Figure 4. Fixed Guard on Belt and Pulley	Figure 5. Fixed Guard on Planer
Figure 6. Adjustable Guard on Table Saw	Figure 7. Adjustable Guard on Horizontal Band Saw
8. Self-Adjusting Guard on Table Saw	Figure 9. Self-Adjusting Guard on Jointer

Table 2. Types of Machine Guards

Types of Machine Guards
Type	Safeguarding Action	Advantages	Limitations	Examples
Fixed	Provides a barrier and is a permanent part of machine.	• Can be constructed to suit many specific applications. • Can provide maximum protection. • Usually requires little maintenance. • Suitable to high production, repetitive operations.	• May interfere with visibility. • Machine adjust-ment and repair often require removal of guard. • Other means of protecting maintenance personnel often required (i.e., lockout).	Use on: • In-running rolls. • Belts and pulleys (see Figure 4). • Power transmission apparatus. • Cutting heads of planers and other automatic-feed equipment (see Figure 5).
Adjustable	Provides a barrier that may be adjusted to facilitate a variety of production operations.	• Can be constructed to suit many specific applications. • Can be adjusted to admit varying sizes of stock.	• Hands may enter danger area protection may not be complete at all times. • May require frequent maintenance or adjustment. • Operator may make guard ineffective. • May interfere with visibility.	Used on woodworking machinery, such as: • Table saws (see Figure 6). • Routers. • Shapers. • Band saws (see Figure 7).
Self-adjusting	Provides a barrier that moves according to the size of the stock entering the point of operation. Guard is in place when machine is at rest. Guard pushes away when worker moves stock into point of operation.	• Off-the-shelf guards are often commercially available. • Do not require manual adjustments.	• Does not provide maximum protection. • May interfere with visibility. • May require frequent maintenance and adjustment.	Used on woodworking machinery, such as: • Table saws (see Figure 8). • Radial saws. • Band saws. • Jointers (see Figure 16).

Source: Adapted from Concepts and Techniques of Machine Safeguarding, U.S. Department of Labor, OSHA.

Other Means of Safeguarding Machines

Additional methods for safeguarding machines include guarding by location or distance, feeding methods, and appropriate placement of controls. None of these methods should replace machine guards, however. It is always important to provide a guard or barrier that prevents access to the danger area. Table 3 describes these other safeguarding methods.

Table 3. Other Methods of Safeguarding Machines

Other Methods of Safeguarding Machines
Method	Safeguarding Principle	Examples	Comments
Location/distance	Dangerous parts of machinery positioned so that they are not accessible to workers duringnormal operation.	• Placement of machine's power apparatus against wall. • Fencing off access to automatic machines. • Feeding long stockinto machine.	Not always feasible, particularly on nonautomatic machines.
Automatic Feeding and Ejection Methods	Operator not required to place his or her hands in the danger area.	• Self-feeder planers. • Sanders. • Lathes.	Malfunctioning can create hazard. Controls should be set at a distance.
Prevent Accidental Startup	Controls shrouded orrecessed.	Standard on manymachines.	Off switch should beeasily accessible, and operator should be ableto operate machine withease.
Miscellaneous	Hazardous part of machine automatically retracted after operation is complete.	Counterweight/stroking mechanisms that return blade to rest after stock has been cut on over-head swing and radialsaws.	Improperly adjusted counterweights can create hazard. Blade may travel in wrong direction ormay fail to retract.
Placement ofControls	Place controls sufficientlyfar from point of opera-tion to prevent reachinginto point of operation.	Two hand controls sit ata distance from the pointof operation.	Stopping time ofmachine is a factor incalculating the distance.

Source: Accident Prevention Manual for Industrial Operations, National Safety Council