Rotating and Reciprocating Movements

All machines operate by rotating or reciprocating motion or by a combination of these motions. For example, rotary cutting and shearing mechanisms, rotating wood stock, flywheels, shaft ends, and spindles all rotate. Rotating action is hazardous regardless of the speed, size, or surface finish of the moving part. Rotating parts and shafts, such as stock projecting from the chuck of a lathe, can catch hair or clothing and draw the operator in. This can seriously mangle or crush the operator. Rotating parts and stock can also force an arm or hand into a dangerous position, breaking bones and lacerating or severing a hand or other parts of a limb. Bolts, projecting keys, or screws on rotating parts increase the danger of getting caught by the rotary part. Operators can also be struck by a projecting bolt or key.

Principal Safety Hazards of Woodworking and Methods of Control

Reciprocating movement is back-and-forth or up-and-down motion. Operators can be caught and crushed by reciprocating movement when the moving part approaches or crosses a fixed part of the machine. (See Figure 1.)

Source: Concepts and Techniques of Machine Safeguarding, OSHA


Figure 1. Reciprocating Movement

In-Running Nip Points

In-running nip points (or pinch points) are a special danger arising from rotating or reciprocating parts. They occur whenever machine parts move toward each other or when one part moves past a stationary object. Parts of the body may be caught between or drawn into the nip point and crushed, mangled, or severed. Figure 2 shows some in-running nip points that may be encountered in the woodworking industry. The nip points in this figure are located where the belts or chains approach the pulleys or gears, or where the rotating parts approach the stationary components.

Kickbacks

Kickbacks occur when a saw seizes the stock and hurls it back at the operator. This can happen when the stock twists and binds against the side of the blades or is caught in the teeth. A blade that is not sharpened, or that is set at an incorrect height, can cause kickbacks. Poor-quality lumber (in other words, frozen lumber or lumber with many knots or foreign objects such as nails) can also result in kickbacks. Hazards due to kickbacks are most likely when there is a lack of safeguards, such as spreaders, anti-kickback fingers, and gauge or rip fences. Kickbacks occur more often when cutting parallel to the wood grain (ripping) than when cross-cutting.

Source: Concepts and Techniques of MachineSafeguarding, OSHA


Figure 2. In-Running Nip Points

Flying Chips

Employees may be exposed to splinters and chips that are flung by the cutting action of woodworking equipment.

Tool Projection (Unbalanced Cutter Heads)

Many pieces of woodworking equipment-such as routers, shapers, and molders-employ rotating cutter heads with multiple knives. Cutter heads that are not properly adjusted, or that are poorly mounted or have broken knives, can become unbalanced. Balance is critical for keeping knives secured to a rapidly moving cutter head. The centrifugal forces on an unbalanced cutter head can fling the knives from the tool and severely or fatally injure the operator or other nearby personnel. Using the wrong tool on a cutter head or using a tool at a higher speed than it was designed to operate at also can cause tool breakage and projection.

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

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.

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

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

What Procedural and Administrative Controls Are Needed to Protect Employees from Equipment Hazards?

• Use appropriate equipment for the job.
  
  Workers can be seriously injured if they do not use the correct equipment for a job. Use machines only for work within the rated capacity specified by the machine manufacturer. Use the correct tools on a given machine. For example, when using a circular saw, use the correct blade for the required cutting action. Similarly, you must only mount blades, cutter heads, or collars on machine arbors that have been accurately sized and shaped to fit these parts.
  
  
• Train workers on machine use and allow only trained and authorized workers to operate and maintain the equipment. Workers should understand the purpose and function of all controls on the machine, should know how to stop the equipment in an emergency, and should be trained on the safety procedures for special set-ups.
  
  Operator training should include hazards associated with the machine, how the safeguards protect the worker from these hazards, under what circumstances the guard may be removed (usually just for maintenance), and what to do if the guard is damaged or not functioning properly.
  
  Employees should be able to demonstrate their ability to run the machine with all safety precautions and mechanisms in place.
  
  
• Frequently inspect equipment and guards.
  
  Ensure that: (1) the operator and machine are equipped with the safety accessories suitable for the hazards of the job, (2) the machine and safety equipment are in proper working condition, and (3) the machine operator is properly trained. Document the inspections and keep the records. Documentation should identify the machine, inspection date, problems noted, and corrective action taken. Noting problems helps to ensure that corrective action will be taken, that operators on all shifts will be made aware of any potential danger, and that any pattern of repeat problems on a particular machine can be detected and resolved as early as possible.
  
  
• Use equipment only when guards are in place and in working order.A worker should not be allowed to operate a piece of woodworking equipment if the guard or any other safety device, return device, spreader, anti-kickback fingers apparatus, guard on in-running rolls, or gauge or rip fence is not functioning properly. When guards cannot be used (during rabbeting or dadoing, for instance), you must provide combs, featherboards, or suitable jigs for holding the stock.
  
  
• You must provide your employees with push sticks or other hand tools so that their hands are away from the point of operation when they work on small pieces of stock.A push stick is a strip of wood or block with a notch cut into one end that is used to push short or narrow lengths of material through saws. (See Figure 10.) Using push sticks keeps stock from tipping and prevents the operator's fingers from coming in contact with blades.
  
  
  Figure 10. Push Stick and Push Block
  
  
• Use a brush or stick to clean sawdust and scrap from a machine. Never allow your employees to clean a saw with their hands or while the machine is running.
  
  
• Provide regular preventive maintenance. Regularly clean and maintain woodworking equipment and guards. Ensure that blades are in good condition. Knives and cutting heads must be kept sharp, properly adjusted, and secured. Sharpening blades prevents kickback. You must also remove any cracked or damaged blades from service. Keep circular saw blades round and balanced. You must remove dull, badly set, improperly filed or improperly tensioned saws from service, and immediately clean saws to which gum has adhered.
  
  
• Never leave a machine unattended in the "on" position. Make sure that workers know never to leave a machine that has been turned off but is still coasting.
  
  
• Maintain proper housekeeping. Workers have been injured by tripping and then falling onto the blades of saws. You must keep floors and aisles in good repair and free from debris, dust, protruding nails, unevenness, or other tripping hazards. Do not use compressed air to blow away chips and debris. Make sure you have a non-slip floor.
  
  
• Do not allow workers to wear loose clothing or long hair.Loose clothing or long hair can be easily caught up in rotating parts.
  
  
• Never saw freehand. Always hold the stock against a gauge or fence. Freehand sawing increases the likelihood of an operator's hands coming in contact with the blade.
  
  
• See the "Personal Protective Equipment" section, located near the end of this guide, for a discussion of PPE.
  
  
• Use appropriate personal protective equipment.See the "Personal Protective Equipment" section of this guide for additional information.
  
  

• Ripsaws and crosscut saws. Enclose the portion of the saw above the table with a self- adjusting guard, as shown in Figure 11. The guard must adjust to the thickness of the material being cut and remain in contact with it [29 CFR 1910.213 (c)(1) and (d)(1)]. Hinge the guard so that the blades can be easily changed.
• For ripsaws, use a spreader to prevent material from squeezing the saw or kicking back during ripping [29 CFR 1910.213(c)(2)]. Use anti-kickback fingers to hold the stock down in the event that the saw kicks back the material [29 CFR 1910.213(c)(3)].
• Guard all belts and in-running nip points [29 CFR 1910.212(a)(1), 1910.219(d) and (e)].
• Always guard the portion of the blade below the table. Operators must be protected from possible contact when reaching under the table [29 CFR 1910.213(a)(12)].

• Attach a brake to the motor's arbor to stop the saw from coasting after it has been cut off, or have the operator remain at the saw station once the motor is shut off until the blade stops turning.
• Guard feed rolls on self feed circular saws by ahood or guard to prevent hands from coming into contact with in-running rip points [1910.213(f)(1)].
  

• Keep hands out of the line of the cut.
• Use proper blade for cutting action (for ex ample, don't use crosscut blade for ripping).
• Operate saw at speed specified by the manufacturer.
• Maintain and sharpen blade [1910.213(s)(2)].
• Leave sufficient clearance for stock.
• Remove cracked saws from service [29 CFR 1910.213(s)(7)].
• Stand to side of the saw blade to avoid injury due to kickback.
• Guide stock parallel to the rip fence to minimize the potential for kickback.
• Use a push stick for small pieces of wood and for pushing stock past the blade. [1910.213(s)(9)]
• Avoid crosscutting long boards on table saws. Considerable hand pressure is required close to the saw blade, and the boards create a safety hazard to other people.
• Use a filler piece between the fence and the saw blade when necessary (e.g., when there is little clearance on the fence side).
• Properly support all pieces of stock, including the cut and uncut ends, scrap, and finished product.
  
  

Overhead Swing and Straight Line Pull Cutoff Saws

These are special types of circular saws, which are also used for straight cutting. They are preferred for cutting long pieces of stock. The overhead swing saw is suspended from the ceiling, as shown in Figure 12; the saw is generally attached directly to the motor shaft. To run the saw the operator pulls it forward like a pendulum.


Figure 12. Overhead Swing Saw

Injuries can occur if the operator reaches to remove a section of board while the blade is coasting or idling, or if the operator tries to measure a board or position it while the saw is still running. Injuries can also occur if an improperly adjusted saw swings beyond its safe limits.

• Enclose upper half of saw and arbor end with a fixed guard; enclose the point of operation (the lower part of the blade) with a self-adjusting hood. The hood must drop on top of and remain in contact with the table or stock. When the saw returns to the back of the table, the hood must cover the lower portion of the blade [29 CFR 1910.213(g)(1)].
• Ensure that the saw contains an automaticdevice (for example, a counterweight) to return the saw to the back of the table after the cut has been made [29 CFR 1910.213(g)(2)].
• Install a latch with a rachet release on the handle, nonrecoil spring, bumper, or other device to keep the saw from rebounding from its idle position.
• Use limit chains or other means to keep saw from moving beyond the front or back edge of the table [29 CFR 1910.213(g)(3)]. (See Figure 12.)
• Enclose overhead drive with a fixed guard [29 CFR 1910.219].

• Position the piece to be cut before starting the saw.
• Stand at the side of the saw blade when the sawis running, and use the hand nearest the handle to operate the saw. (This keeps the operator's body out of the line of the saw.)
• Remove cracked and defective saw blades from service [29 CFR 1910.213(s)(7)].
• Keep hands out of the line of the cut.
• Make sure guards and counterweights areproperly adjusted at all times. Take improperly adjusted saws out of service [29 CFR 1910.213 (s)(1)].
  

• Enclose the upper half of the saw (from the blade down to the end of the saw arbor) with a fixed hood. Guard the lower half with a self-adjusting, floating guard that rises and falls and automatically adjusts to the thickness of the stock [29 CFR 1910.213(h)(1)]. Figure 13 shows a radial saw with a self-adjusting guard covering the lower half of the blade.

• Make sure the saw has a return device. The front end of the unit must be slightly higher than the rear, so that the cutting head will return to its original position when released by the operator. This should also prevent the cutting head from rolling or moving the arm due to gravity or vibration [29 CFR 1910.213(h)(4)].
• Install an adjustable stop to limit forward travel distance of the blade during repeat cuts [1910.213(h)(3)].
• Guard feed rolls [29 CFR 1910.213(b)(7)].
• For ripping, install non-kickback fingers on both sides of the saw blade [29 CFR 1910.213(h)(2)].
• Use a spreader in ripping operations to prevent the cut in the wood from immediately closing and binding the blade.

• During crosscutting, operate the saw on the side of table with the handle.
• Make sure that stock is fed in the correct direction. Post a warning label on the hood showing the direction of saw rotation [29 CFR 1910.213(h)(5)].
• Measure boards against a stop gauge, or turn off the saw if measuring by rule. (Wait for the blade to stop before moving materials or making measurements.)

• Guard the blade entirely except at the point ofoperation (the working portion of the blade between the bottom of the guide rolls and the table) [29 CFR 1910.213(i)(1)]. (See Figure 14.)
• Use a self-adjusting guard for the portion of the blade between the sliding guide and the upper saw so that it raises and lowers with the guide [29 CFR 1910.213(i)(1)].
• Properly adjust the blade guide post to fit the thickness of the stock and to provide additional guarding.
• Fully enclose the pulley mechanism [29 CFR 1910.219(d)].
• Guard feed rolls [29 CFR 1910.213(i)(3)].
• Install a brake on one or both wheels to minimize the potential for coasting after the saw has been shut off; or do not retrieve material until the blade has stopped.
• Make sure the saw includes a tension control device to indicate proper blade tension [29 CFR 1910.213(i)(2)].
  

• Use a blade of an appropriate size and type (for example, do not force a wide saw to cut on a small radius).
  
  
  Figure 14. Adjustable Guard on Band Saw
  
  
• Never stop the saw too quickly or thrust a piece of wood against the cutting edge of the teeth after the power has been shut off.
• Periodically examine blades; remove cracked ordefective blades immediately [29 CFR.1910.213(s)(7)].
• Make cuts only when the power is on and not while the saw is coasting.
• Set the guard to just clear the stock being cut.
• Use a push stick to control the stock when it is near the blade.
• Use a special jig or fixture when cutting small pieces of stock.
  
  

• Use a threshold rest (slotted foot) to hold the stock.
• Guard the blade with an adjustable or self-adjusting guard (see Figure 15).
• Guard drive belts and pulleys [29 CFR 1910.213(a)(9)].
• Guard the portion of the blade below the table.

• Make turns slowly; do not make sharp turns with a wide blade; use a narrow blade for sharp turns.
• Make sure the blade is properly attached and secured.
  

• Enclose cutter head with an automatic (springloaded, self-enclosing) guard that exposes the cutter head only when the stock is being fed. The guard must automatically adjust to cover the unused portion of the head, and it must remain in contact with the material at all times [29 CFR 1910.213(j)(3)]. Figure 16 shows the appropriate use of a self-adjusting guard.
  
  
  
  Figure 16. Jointer with Self-Adjusting Guard
  
  
• Adjust the cylindrical cutter head so that the knife projects no more than 1/8 inch beyond the cylindrical body of the head [29 CFR 1910.213(j)(1)].
• Adjust the cutter head so that the clearance between the path of the knife projection and the rear table is no more than 1/8 inch [29 CFR 1910.213(j)(2)].
• Keep the clearance between the table and the head as small as possible [29 CFR 1910.213(j)(2)].
  

For vertical head jointers:

• Completely enclose cutter head, except for slot to apply the material for jointing. This guard can be part of the local exhaust system.

Work Practices

• Use hold-down push blocks when jointing wood narrower than 3 inches.
• Avoid deep cuts; they increase the likelihood of kickbacks and require a larger table opening.
• As a general rule, never joint pieces of material that are less than four times the width of the bed opening.
• Check knives regularly for proper setting and adjustment, but only when the power is shut off.
  
  

• As shown in Figure 17, enclose the spindle with an adjustable guard or cage [29 CFR 1910.213(m)(1)]. For straight-line shaping, the fence frame should include the guard. The fence should contain as small an opening as possible for the knives, and should extend at least 18 inches on either side of the spindle. Split adjustable fences are useful for guarding when the entire edge of the stock is to be shaped.
  
  
  Figure 17. Sharper with Adjustable Guard
  
  
• Mount a ring guard around the cutting bit to reduce contact with the bit.
• Guard automatic feed rollers [29 CFR 1910.213(b)(7)].
• Ensure that double-spindle shapers have a starting and stopping device for each spindle [29 CFR 1910.213(m)(3)].
• Use a safety collar to minimize the potential for tool projection.
  
  

• Maintain the knives. Make sure they are preci-sion-ground to apply uniform pressure. Make sure the knives are balanced and fit properly [29 CFR 1910.213(s)(2)].
  Train operators to listen for "chatter," which indicates that knives are out of balance. To start the machine, operators should apply the power in a series of short starts and stops to slowly bring the spindle to operating speed.
• Use templates, jigs, and fixtures to distance the operator's hands from the point of operation. Featherboards may be clamped to the fence for straight line shaping.
• Cut in the opposite direction of the spindle's rotations.
  
  

Power-Feed Planers/Moulders

Also called surfacers, planers are used to dress and size rough-sawed lumber on one or more sides. They plane boards to an even thickness. Stock passes under or between cylindrical cutter heads with multiple knives. (See Figure 18.) Planers are similar to jointers except that the cutter head is above, or above and below, the stock. The operator adjusts for the cut and then feeds stock into the in-feed side of the machine. The surface board is retrieved from the out-running end.

Specific Woodworking Equipment Hazards and Controls

Automatic feeding mechanisms make this equipment less hazardous. However, operators' hands may be pulled into the cutting area, and can come in contact with the point of operation while adjusting blades. Operators' hands also may be pinched between the stock and in-running rolls, if the feed system is not properly guarded.


Figure 18. Planer

• Completely enclose belts and pulleys of line shaft with sheet metal or heavy mesh guards; guards must be used regardless of the location of the line shaft [29 CFR 1910.219(a)(1)].
• Cover cutting heads with a metal guard or cage. The exhaust system may be integrated with the guard [29 CFR 1910.213(n)(1)].
• Guard feed rolls with a wide metal strip or bar that will allow boards to pass but that will keep operators' fingers out [29 CFR 1910.213(n)(3)].
• Provide barriers at the loading and unloading ends to keep hands out of point of operation.
• Install anti-kickback fingers on the in-feed side across the width of the machine.
• Use a barrier or guardrail when the machine isrunning.
  
  

• Stand back once the boards have been put through to avoid injuries from kickback and flying splinters.
• Do not feed boards of different thicknesses. Thinner boards will be kicked back.
  
  

• For automatic wood-turning lathes with rotating knives, cover the cutter head with a metal shield or hood that completely covers the knives and material, except at the contact points, when the machine is in operation [29 CFR 1910.213(o)(3)]. A hinged shield permits adjustments when needed.
• For manual lathes, cover the cutter heads as completely as possible with a hood or shield [29 CFR 1910.213(o)(2)].
• Cover lathes used for turning long stock with long curved guards extending over the top of the lathe [29 CFR 1910.213(o)(4)]. Such guards prevent the stock from being thrown from the machine, should the stock come loose.
• Install a brake for bringing the stock to a complete stop after the power is shut off.
• On hand-fed lathes, guard the tool and point of operation with a plexiglass tool guard, as shown in Figure 19.
  
  
  Figure 19. Plexiglass Guard on Lathe Protects Operator from Flying Chips
  
  
• Enclose the power transmission with a fixed guard [29 CFR 1910.219].

Sanders Sanders finish stock by using a coated abrasive surface to remove material. Figures 20 and 21 show the three general types of sanders: drum, belt, and disc. A belt sander uses a system of pulleys to move the abrasive material across the stock. Either the wood is fed manually or automatically into the machine or the sanding belt is pressed toward the wood, which is located on a working table.


Figure 20. Drum Sander


Figure 21. Belt and Disc Sander

Sanders produce a considerable quantity of fine wood dust. Wood dust hazards and controls are discussed in detail in the section "How Can I Protect My Employees from Wood Dust?" All sanders should be carefully ventilated. The primary safety hazard of belt sanders is that workers may catch their hands, clothing, or jewelry in the in-running rolls. Also, contact with an abrasive surface can cause abrasions and lacerations.

• Guard feed rolls with a semi-cylindrical guard to prevent the operator's hands from coming in contact with the in-running rolls on automatic sanders. The guard design must allow for adjustment to any thickness of stock [29 CFR 1910.213(p)(1)].
• Guard the unused run of the sanding belt against accidental contact. These guards must prevent the operator's hands or fingers from coming in contact with nip points [29 CFR 1910.219].
• Enclose drum and disc sanders with guards, except for the portion of the sander's drum above the table. The guard can consist of a protective cover at the rear side of the wheel and a hinged cover around the wheel periphery [29 CFR 1910.213(p)(2) and (p)(3)].
• Enclose power transmission pulleys with a fixedguard [29 CFR 1910.219].
  
  

• Replace torn, frayed, or excessively worn belts or drums. A worn-out belt, disk, or drum can cause massive heat buildup, which can cause the belt, disk, or drum to tear or break and pelt the surrounding area with projected bits.
• Keep hands away from abrasive surfaces.
• Sand on the downward-moving side of the disk or belt.
  
  

• Enclose the tool with an adjustable tool guard, as shown in Figure 22 [29 CFR 1910.213(m)(1)].
  
  
  Figure 22. Router with Adjustable Tool Guard
  
  
• Equip routers with a spindle braking system that gradually engages.
• Guard feed rolls [29 CFR 1910.213(b)(7)].
  
  

• Properly attach and secure tools to the holder.
• Label cutting tools and holders with the maximum permissible spindle speed.
• Use tools only as intended.
  

Tenoning Machine

Tenoning machines use cutter heads and/or saw blades to form projections (tenons) on pieces of stock. Each tenon can be inserted into a cavity (mortise) on another piece of wood to form a mortise and tenon joint. Figure 23 shows a single-end tenoning machine.


Figure 23. Single-End Tenoning Machine

• Enclose feed chains and sprockets of double end machines, except for the portion of the chain conveying stock [29 CFR 1910.213(k)(1)].
• The cutting head and saws must be guarded with metal guards. Cover the unused part of the periphery of the cutting head. If an exhaust system is used, the guard must form part of the exhaust system [29 CFR 1910.213(k)(3)].
  

• Use safety bit chucks with no projecting screws [29 CFR 1910.213(l)(1)].
• Enclose boring bits with a guard that encloses the bit and chuck above the material being worked [29 CFR 1910.213(l)(2)].
• Enclose the top of the cutting chain and driving mechanism [29 CFR 1910.213(l)(3)].
• If a counterweight is used, prevent it from dropping by bolting it to the bar or attaching a safety chain to it [29 CFR 1910.213(l)(4)].
• Cover operating treadles with inverted U-shaped guard to prevent accidental tripping [29 CFR 1910.213(l)(6)].
  
  

• All of the metal framework on electrically driven machines must be grounded, including the motor, motor casing, legs, and frame. This includes other equipment such as lights that may be mounted on the machine.
  
  
• All circuit breakers and fuse boxes must be labeled to indicate their purpose-that is, what area of the plant they power or protect. Appro priately rated fuses must be used. All unused holes in electric boxes must be covered.
  
  
• Electrical cords, cables, and plugs must be kept in good repair. Flexible cords and cables must be fastened so that there is no direct pull on joints or terminal screws. Cords and cables must be free of splices and must not run through windows, doorways, or holes in the wall.
  
  
• Junction boxes, outlets, switches, and fittings must be covered.
  
  
• All electrical components must be approved by a Nationally Recognized Testing Laboratory for the specific location where the equipment will be used.
  
  
• All machines must have a main power disconnect for lockout/tagout.
  
  

• A magnetic switch or other device to prevent automatic restarting of the machine after a power failure. Such an unexpected start-up could expose the worker to moving parts.
  
  
• An emergency stop device (panic bar or deadman switch) within reach of operators working in the normal operating position.
  
  
• Clearly marked controls that are within easy reach of the operator and away from the hazard area.
  
  

• They contain large quantities of fuel in the form of wood and wood products, sawdust, and flammable materials such as paints, oil finishes, adhesives, solvents, and liquid propane for internal combustion engines. Woodworking facilities are especially at risk for fire due to the abundant production of sawdust, which will ignite and burn far more easily than whole pieces of lumber. Sanders, routers, and shapers in particular produce large amounts of fine dust. Very fine wood dust is especially hazardous. It can accumulate on rafters and other building structural components and in unexpected spots all around your facility, far from the point of generation.
• They contain ignition sources, such as potentially faulty electrical wiring, cutting and welding operations, sparking tools, propellant-actuated tools, and employee smoking. There is also the potential for static electrical discharges and lightning.
  
  

• Ensure the proper use and storage of flammable materials, such as paints, finishes, adhesives, and solvents.
  
  
• Segregate tasks particularly prone to fire and explosion hazards, such as spray painting, welding, and use of powder-actuated nail guns.
  
  
• Train employees to recognize, avoid, and correct potentially hazardous conditions and behaviors. Train employees so that they are acquainted with the special equipment and aspects of building design related to dealing with fires and explosions.
  
  
• Control ignition sources. This involves using electrical systems rated for the projected use and protected by appropriate circuit breakers, grounding all equipment prone to accumulating static electrical charges, grounding entire buildings against the possibility of lightning strikes, and controlling and banning smoking in and around the workplace. Consult Subpart S of OSHA's General Industry Standards for more information on electrical design requirements.
  
  
• Never permit blow-down of accumulated dust with compressed air. Blowing dust with compressed air will create the very type of dust cloud that presents the greatest explosion hazard.
  
  
• Provide continuous local exhaust ventilation on all woodworking machines. The local exhaust systems must have a suitable collector. Dust collection systems must be located outside the building, unless the exceptions described in NFPA standards are met.
  
  
• Segregate combustible and flammable materials such as lumber stock and chemical solvents from each other and from ignition sources.
  
  
• Ensure that you use equipment with a hazard classification appropriately rated for your work environment.
  
  

• Fire-resistant construction and/or fire-resistant materials (particularly fire doors that could be used to contain the spread of a fire).
  
  
• Explosion relief devices, such as blow-out panels in walls, floors, and ceilings that protect structural integrity in the event of an explosion.
  
  
• Multiple emergency exits that are well marked and easily accessible. These exits should lead people directly away from the areas of greatest likely hazard.
  
  
• Emergency alarms and communications systems to promote rapid evacuation and fire fighting response.
  
  
• Automatic sprinkler systems designed for a worst-case fire scenario.
  
  
• Readily accessible, portable fire extinguishers fully charged with fire retardants appropriate to the types of fires likely to occur in that area.
  
  

• Install an alarm system to warn for necessary action or safe escape [29 CFR 1910.165].
  
  
• Establish emergency plans and fire prevention plans [29 CFR 1910.38].
  
  
• Install battery-operated emergency lighting along the floor to aid in the evacuation of smoke- filled buildings.
  
  
• Store fire-retardant blankets, clothing, and masks in areas where workers could conceivably need them to pass through smoke and flames to reach exits.
  
  
• Maintain first-aid kits designed for the initial treatment of burns and smoke inhalation. These kits should be stored outside the area of fire risk.
  
  

• Exhaust the saw through the bottom of the table. Provide LEV under the blade slot. To decrease the open area between the table and the lower hood, attach a strip of flexible material to the machinery that will cover this area when the hood operates.
  
  
• For increased dust control, add a local exhaust hood above the top of the saw blade. The hood should be integrated with the guard on the upper part of the blade.
  
  
• For further information on control of wood dustfrom circular and other kinds of table saws, please consult the NIOSH Hazard Controls HC10 (See Appendix B).
  
  

• Provide LEV under the blade slot. To increase the collection area of the hood, add holes (1/8 inch in diameter) in the table around the slot area.
  
  
• To collect wood dust from the saw teeth, place a suction nozzle above the table, at the rear of the saw blade.
  
  

• Place a hood underneath the machine head.
  
  

• Control each head with an open-faced hood, located on the table behind the head. For additional protection, use a combination of fixed and adjustable hoods. A fixed open-faced hood can be attached to the rear of the table between the shaper heads. Movable open-faced hoods also can be used on the table. For further information please consult the NIOSH Hazard Controls HC5: Wood Dust from Shapers (See Appendix B).

• Place open-faced hoods above the spinning heads of planers. Each head can be ventilated separately, or one hood can be used to control several heads.
  
  
• Place open-faced hoods around the spinning components of moulders. Each head should be separately controlled.
  
  
• For increased dust control, add a small open-faced hood along the side of the moulder between the main head and the worker.
  
  

• Place an open-faced hood attached to a movablemechanical arm at the point of operation.

• Enclose disc sanders with an exhaust hood, installed below the table; cover the back of the sanding disc at points above the worktable. A system has been developed that supplies pressurized air to the disc inside the hood. The jet of high speed air blows dust particles out of the disc air layer so that they can be captured by the exhaust hood.
  
  
• On random orbital sanders, use an aspirator in combination with a perforated sanding pad. The aspirator creates a vacuum that draws wood dust up through the holes of the sanding pad. An innovative dust control system has been developed that uses additional exhaust and a slotted sanding pad.
  
  

• A new dust control plenum has been designed for orbital sanders. The plenum fits between the sanding pad and the sander body and has a series of exhaust slots along its edges.
  
  
• Enclose horizontal belt sanders with exhaust hoods covering each end of the belt. These hoods control the dust carried by the belt. To further control dust emissions, install an additional hood above the area where the wood is processed. To increase the effectiveness of this system, add a narrow hood and a stripper.
  
  

• Place two open-faced hoods behind the heads of the router table. Connect the hoods to the exhaust ductwork via a flexible hose.
  
  
• Locate an open-faced or slot hood at the rear end of the router table.
  
  
• For further information please consult theNIOSH Hazard Controls HC6: Wood Dust from Automated Routers (See Appendix B).
  
  

• Maintain machines in proper working order. Unbalanced rotating parts or unsharpened cutting tools can give off excessive vibration.
  
  
• Arrange work tasks so that vibrating and nonvibrating tools can be used alternately.
  
  
• Restrict the number of hours a worker uses a vibrating tool during the workday. Allow employees to take 10 to 15 minute breaks from the source of the vibration every hour.
  
  
• Train workers about the hazards of working with vibrating tools. Instruction should include: the sources of vibration exposure, early signs and symptoms of hand-arm vibration syndrome, and work practices for minimizing vibration exposure.
  
  
• Instruct workers to keep their hands warm and dry, and to not grip a vibrating tool too tightly. Workers should allow the tool or machine to do the work.
  
  

• Blows to the head from stock and equipment at certain locations within your manufacturing and shipping operations.
• Threats to the eyes and face from flying wood chips and splinters, dust, and machine parts.
• Cutting and tearing hazards, particularly to the hands and arms, during equipment operations.
• The threat of kickback blows to the body, groin, and legs during stock-cutting and shaping.
• Crushing and laceration threats to the feet, particularly around loading equipment (for example, forklifts) and hand-held power tools (such as chain saws).
• Irritation of the skin, mouth, nose, throat, and lungs from dust, paint, adhesives, and other chemicals.
• The constant threat to hearing from machine noise.
  
  

• Prescription safety glasses,
  
  
• Goggles that fit well over their regular eyeglasses, or
  
  
• Goggles that incorporate corrective lenses mounted behind the protective lens.
  
  

• Equipment and/or materials are stored, operated, or in any way manipulated above shoulder level.
• Fixed objects, such as exposed pipes and beams, present low clearance.
  
  

• Heavy objects (for example, tools, equipment, fork lifts, heavy-duty dollies, drums, wood stock) rolling over, falling onto, or striking them in the feet or legs.
• Sharp objects (for example, broken saw teeth, broken router blades, nails, spikes, or other fasteners) piercing the soles or uppers of their shoes.
• Slippery surfaces.
  
  

• Develop and implement a monitoring program to sample noise levels within the workplace, identify employees for inclusion in the hearing conservation program, and enable the proper selection of hearing protectors.
  
  
• Establish and maintain an audiometric testing program in which qualified professionals periodically test the hearing of all workers whose noise exposures equal or exceed a daily 8-hour average of 85 dBA.
  
  
• Provide hearing protection, at no charge, to all employees exposed to such levels of noise.
  
  

• Suffer from problems associated with wood dust inhalation.
  
  
• Routinely handle wood finishes, adhesives, solvents, or other chemical compounds in containers open to the air they breath.
  
  
• Work in paint spray booths (or booths where other chemicals are sprayed).
  
  

• When feasible, use automated systems for applying coatings and adhesives. Automated systems should be ventilated.
  
  
• Substitute the traditional solvent-based coatings and adhesives with coatings and adhesives that are less toxic. Hot melt, heat seal, aqueous-based, and polyvinyl acetate adhesives are good, less-toxic alternatives to solvent-based adhesives. Higher-solids nitrocellulose, aqueous-based, ultraviolet-cured, and polyester/polyure-thane coatings are also less toxic than solvent-based coatings.
  
  
• Provide adequate local exhaust ventilation for all coating and gluing processes. This includes manual spray, rolling, and brushing operations, automated coating processes, and dip coating. Manual spray operations should be performed in a spray booth or a separate, ventilated spray area. Dip coating should be ventilated with an enclosure or capture hood. Consult the OSHA standard on dip coating (open surface tanks), 29 CFR 1910.108, for detailed requirements on dipping operations.
  
  • The OSHA standard for spray finishing operations, 29 CFR 1910.107, provides detailed requirements for the design and construction of spray booths and rooms, air filters, velocity and air flow requirements, and the (make-up) air supplied to the booth. It is important to maintain the proper air flow in a spray booth. Excessive air pressure decreases the efficiency of the operation, wastes material, and may cause a backlash of vapors and overspray into adjacent work areas. Dirty air filters can decrease the air flow in the booth. Ensure that filters are cleaned and replaced as needed. Although these provisions are designed to prevent the occurrence of a fire or explosion in spray finishing operations, they also assist in protecting workers from the health hazards of the chemicals used in the operation by removing the chemicals from the atmosphere.

• OSHA's Hazard Communication standard, 29 CFR 1910.1200, requires employers to inform their employees about the hazardous substances they handle. Hazard communication programs have three important components: material safety data sheets (MSDSs), training, and labeling requirements.

• Provide respirators and gloves for workers performing manual spray operations. Consult the MSDS to determine what type of glove to use. Operators working downstream of the objects being sprayed inside the booth must be provided with an air-supplying respirator. Provide dip-coat operators with gloves, boots, aprons, and jackets, sleeves, or coats to protect them from possible splashes. Consult the MSDS to determine the appropriate material of protective clothing to provide. The "Personal Protective Equipment" section of this guide provides detailed information on PPE requirements.

• Auxiliary Ventilation System
  Typically, belt sander emissions are controlled only by an exhaust hood covering the drive pulley. The new ventilation system reduced wood dust emitted into the workroom by more than 75% and can easily be built into new belt sanders or added to existing ones. The system consists of two devices: a narrow Auxiliary Hood and an Air Jet Stripper (see Figure 25). The Auxiliary Hood is located between the belt surface and the worktable downstream from the sanding operation. The Air Jet Stripper is located inside the main exhaust hood. These two devices, in combination with the main exhaust hood, decrease wood dust in the workroom without affecting the sanding operations. In addition, the Jet Stripper cleans the belt, reducing the frequency of belt changes. This dust control device is not currently commercially available.

Figure 25. Auxiliary Ventilation System for Horizontal Belt Sanders

Control of Wood Dust from Shapers

Hazard

Wood shapers are a major source of wood dust emissions. Workers exposed to wood dusts have experienced a variety of adverse health effects such as eye and skin irritation, allergy, reduced lung function, asthma, and nasal cancer. NIOSH, therefore, recommends limiting wood dust exposures to prevent these health problems.

Controls

Surveys by NIOSH researchers found that the dust from wood shapers tends to be poorly controlled. The amount of wood dust emitted was found to depend on the sharpness of the cutter, the depth of the cut, the rate at which the wood is fed into the shaper, and the location of the exhaust hood. After studying the usual hood exhaust placement, researchers developed an improved hood configuration that significantly reduced wood dust emissions.

• Modified Exhaust Hood
  Wood shaper emissions are usually controlled by an exhaust hood located at the back edge of the work table which allows the operator to freely move the workpiece over the table. Placing the exhaust hood nearer the cutting head would maximize dust collection, however, this would restrict the operator's freedom to move the workpiece. To overcome this problem, a hood extension with a flexible face opening is added (see Figure 26). The flexible face opening consists of cloth-covered chains that allow the wood to pass through, but stops the wood dust particles. The extension also increases the hood face velocity by minimizing the open face area. This dust control device is not currently commercially available.

Figure 26. Improved Hood Configuration for Shapers

Control of Wood Dust from Automated Routers

Hazard

Automated routers have been found to create significant amounts of wood dust. Workers exposed to wood dusts have experienced a variety of adverse health effects such as eye and skin irritation, allergy, reduced lung function, asthma, and nasal cancer. NIOSH, therefore, recommends limiting wood dust exposures to prevent these health problems.

Controls

NIOSH researchers found that the wood dust generated by automated routers is generally not adequately controlled. To address this problem, researchers designed and tested a new control system that substantially reduced dust emissions.

• Jet Stripper System Automated routers, consisting of a moving router head and table, are capable of routing in any direction. These high speed machines generate substantial amounts of wood dust. Generally, the wood dust is controlled by a local exhaust system located at the router head. Despite this control, significant amounts of wood dust are emitted into the workroom. A computer controlled Jet Stripper System was developed to control these emissions (see Figure 27). This system consists of 24 jets combined into 8 operational units uniformly located around the inside periphery of the brush holder. The Jet Stripper and brush surround the router bit. The jets are supplied with pressurized air and are activated by pneumatic valves as needed. The air slows down the dust particles so they can be collected by the local exhaust hood. Testing shows that this system reduces wood dust emissions by 90 percent. The Jet Stripper does not interfere with the operator, requires minimal maintenance and is inexpensive to install and operate. This control can also be used with conventional, one-dimensional routers with some modification. This dust control device is not currently commercially available.

Figure 27. Computer-Controlled Jet Stripper System for Controlling Emissions from Automated
Routers

Control of Wood Dust from Large Diameter Disc Sanders

Hazard

The use of large diameter disc sanders creates significant amounts of wood dust. Workers exposed to wood dusts have experienced a variety of adverse health effects such as eye and skin irritation, allergy, reduced lung function, asthma, and nasal cancer. NIOSH, therefore, recommends limiting wood dust exposures to prevent these health problems.

Controls

Surveys by NIOSH researchers found that wood dust created by large diameter disc sanders is often not effectively controlled. To address this problem, researchers designed a ventilation control system that significantly reduced wood dust emissions into the workroom.

• Jetstripper System
  The standard dust control arrangement for disc sanders usually consists of an exhaust hood under the worktable that covers the lower half of the disc and a cover around the back of the sanding disc above the worktable. Even with this control, significant amounts of wood dust are emitted into the workroom. A Jet Stripper System was designed to improve dust control (see Figure 28). The Jet Stripper supplies pressurized air to the disc inside the hood. The jet of high speed air blows the dust particles out of the disc air layer so they can be captured by the exhaust hood. Also, the jet removes the dust particles embedded in the sanding disc. The Jet Stripper System reduced wood dust emissions by an average of 60 percent in laboratory studies. The advantages of this control are that it does not interfere with the operator, requires minimal maintenance and is inexpensive to operate. The Jet Stripper may also extend the life of the sanding discs by dislodging the wood dust from the sanding surface. This dust control device is not currently commercially available.

Figure 28. Jet Stripper System for Improving Dust Control from Disc Sanders

Control of Wood Dust from Random Orbital Hand Sanders

Hazard

Random orbital (rotating) hand sanders have been found to create significant amounts of wood dust. Workers exposed to wood dusts have experienced a variety of adverse health effects such as eye and skin irritation, allergy, reduced lung function, asthma, and nasal cancer. NIOSH, therefore, recommends limiting wood dust exposures to prevent these health problems.

Controls

NIOSH researchers found that wood dust created by random orbital hand sanders is often poorly controlled. To address this problem, researchers designed and tested a new control system for these hand sanders that significantly reduced dust emissions.

• Additional Exhaust System
  Random orbital hand sanders are widely used in woodworking applications. The dust generated by these tools is sometimes controlled by an aspirator in combination with a perforated sanding pad. The aspirator creates a vacuum to draw wood dust up through holes in the sanding pad. It was found that, in spite of this control, large amounts of wood dust were still emitted into the workroom. A new control system that uses Additional Exhaust and a Slotted Sanding Pad was implemented to increase dust control (see Figure 29). The increased suction of the additional exhaust alone causes the sanding pad to be pulled to the work surface making the tool difficult to use. To alleviate this problem, curved slots are cut into the sanding pad. This relieves the pressure caused by the extra suction and provides additional dust control at the pad periphery. The new dust control system reduces dust emissions by approximately 90 percent compared with the currently used aspirator controlled sander. The new sander does not interfere with the operator, requires no special maintenance and is inexpensive to operate. This dust control device is not currently commercially available.

Figure 29. Dust Control System for Random Orbital Hand Sanders

Hazard
Orbital hand sanders have been found to create significant amounts of wood dust. Workers exposed to wood dusts have experienced a variety of adverse health effects such as eye and skin irritation, allergy, reduced lung function, asthma, and nasal cancer. NIOSH, therefore, recommends limiting wood dust exposures to prevent these health problems.

Controls
NIOSH researchers found that the wood dust generated by orbital hand sanders is often poorly controlled. To address this problem, researchers designed and tested a new control system for these hand sanders that significantly reduced dust emissions.

• Dust Control System
  Orbital hand sanders are extensively used in woodworking processes. The dust from these sanders is generally not controlled although some are equipped with dust removal capabilities. However, even the sanders having dust removal do not effectively control the wood dust generated by the sanding operation. Therefore, a new control approach was developed. A Dust Control Plenum was designed and tested on an orbital sander (see Figure 30). The plenum fits between the sanding pad and the sander body and has a series of exhaust slots along its edges. An exhaust connection on the top of the sander pad connects the plenum with a vacuum source. Laboratory tests show that the plenum reduces wood dust emissions by approximately 90 percent. The plenum does not interfere with the operator's activities, requires no special maintenance, is inexpensive to operate, and can be used on any sander, pneumatically or electrically powered. This dust control device is not currently commercially available. Call NIOSH for more information.

Figure 30. Dust Control Plenum for Orbital Hand Sanders

Control of Wood Dust from Table Saws

Hazard

Table saws have been found to create significant amounts of wood dust. Workers exposed to wood dusts have experienced a variety of adverse health effects such as eye and skin irritation, allergy, reduced lung function, asthma, and nasal cancer. NIOSH recommends limiting wood dust exposures to prevent these health problems.

Controls

NIOSH researchers found that the wood dust generated by table saws is often poorly controlled. To address this problem, researchers designed and tested a control system for table saws that significantly reduced wood dust emissions.

• Local Exhaust Hood
  Table saws are widely used in many types of woodworking operations. Although they are sometimes used only sporadically, they are found to generate significant amounts of dust. The traditional method of dust control for table saws is exhaust through the bottom of the table. This is often not adequate to control the large amounts of high speed dust that are generated by the saw blade. To better control the dust, NIOSH researchers added a Local Exhaust Hood to the table saw (see Figure 31). Another modification involved the addition of a divider plate in the table base to increase the exhaust velocity and aid clean out. The table exhaust location was also relocated. The exhaust hood, when placed over the top of the blade saw, contains the dust as it is thrown from the saw blade. Laboratory testing indicates that the exhaust hood reduces wood dust emissions by greater than 90 percent when it is installed on a typical table saw. The hood is designed so that it will not interfere with the operator's activities, is easy to install and maintain, and is inexpensive to operate. This dust control device is not currently commercially available.

• request full-service consultation assistance;
• involve their employees in the development, operation, and improvement of all elements of the program;
• work with project consultants for at least one year to improve worker protection at the site; and
• meet other program requirements. In return, employers receive public recognition for exemplary efforts and achievement, reap the benefits of extensive professional assistance, and
• may be eligible to receive a 1-year exemption from OSHA general scheduled inspections.