Woodworking shops can be very dangerous. There are blades, cutting edges, and shapers which have no more respect for flesh than for wood. Improperly or inadequately guarded machines are one of the top OSHA violations. Not only are lacerations and amputations and eye injuries of concern in woodworking shops but also wood dust and finishing chemicals. These guidelines are not all inclusive but rather serve to provide a framework for shop safety. The following applications are reviewed:
- Milling equipment
Milling equipment includes table saws, radial saws, jointers, and planers. Production machines includes table, band and scroll saws, lathes, jointers, shapers, planers, drill presses, sanders, tenon/mortising machines, jig saws, routers, circular saws, drills, and pneumatic guns. The major area of concern related to the assembly of production material is related to ergonomics. Finishing generally involves chemicals and the hazards associated with their use. Issues associated with wood dust, noise, electricity and machine maintenance are addressed separate from each section.
Injuries can occur if the operator’s hands slip as the stock is being fed into the saw or the hands are too close to the blade. The operator can also be injured when removing wood from the table.
The portion of the saw above the table should have a self adjusting guard. The guard must adjust to the thickness of the material being cut and remain in contact with it.
The motor’s arbor should have a brake to stop the saw from continuing after it has been shut off. If a brake is not practical the operator should remain at the station until the blade stops turning.
Hands should never be placed in the cut line and both should remain in contact with the stock, table or push stick at all times when blade is turning. A push stick should be used when pushing stock past the blade.
The blade under the table and the power transmission apparatus should be enclosed or situated in such a way to prevent operator contact.
A kickback occurs when the blade catches the stock and throws it back toward the operator. Kickbacks are more likely to occur when ripping rather than crosscutting. These can result if the blade isn’t properly maintained or the height isn’t correct. Poor quality lumber is a major contributor to kickback.
For ripsaws a spreader should be used to prevent materials from squeezing the blade or kicking back. Anti-kickback fingers should be used to hold the stock down in the event that the saw kicks back the stock.
- Use the proper blade
- Operate the saw at the proper speed
- Use a well maintained sharp blade
- Stand to the side of the blade
- Properly support all pieces of the stock
- Guide stock parallel to the rip fence
- Avoid crosscutting long boards on table saws
- Remove damaged blades from service
- Flying particles may be thrown by the saw eye protection must be worn
Radial saws have circular blades that either rip or crosscut. They are much more versatile than table saws. The saw arm can be raised or lowered and swung to adjust the depth and angle of the cut. The blade can be replaced shaping cutters, sanders, and other accessories.
The most significant hazard is contact with the turning saw blade. The upper half of the saw should have a fixed hood. The lower half should be guarded with a self adjusting, floating guard that automatically adjust to the thickness of the stock. The cutting head should return to its original position when released by the operator. An adjustable stop should be installed to limit forward travel distance of the blade during repeat cuts.
Stock may be measured against a stop gauge without turning the blade off. The blade must be stopped before moving materials or measuring by ruler.
A kickback may occur if stock is caught in the blade or fed in the wrong direction. When ripping non kickback fingers should be installed on both sides of the blade. A spreader may be used when ripping to prevent binding the blade. The hood should show the direction of blade rotation so stock will be in the correct direction. When crosscutting operator the saw on the side of the table with the handle.
- Flying particles may be thrown by the saw eye protection must be worn.
- Use the proper blade
- Remove damaged blades from service
- During crosscutting operate the saw on the side of the table with a handle
Jointers are used to join pieces of material. The operator passes stock over a cylindrical multiple knife cutter head while keeping the stock flush against a guide. The depth of the cut is adjustable.
Injuries occur when fingers contact the cutting knives. For hand fed jointers with a horizontal cutting head the head should be enclosed with an automatic 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 must remain in contact with the material at all times. The cylindrical cutter head knife should be adjusted so that the knife projects no more than 1/8 inch beyond the cylindrical body of the head. The clearance between the path of the knife projection and the saw table should be no more than 1/8 inch. The clearance between the table and the head should be as small as possible. For versatile head jointers the cutter head should be completely enclosed except for the slot to apply the stock for jointing.
- Use hold down push blocks foe wood narrower than 3 inches
- Avoid deep cuts. Make several shallow cuts
- Eye protection is required
- Knives should be checked regularly for proper seating and adjustment
Planers are used to dress and size sawed lumber on one or more sides. The cutter heads are located above or below the stock. The stock passes under or between cylindrical cutter heads with multiple knives. An operator’s hands can come into contact with the point of operation while adjusting the blades. They may also be pinched between the stock and rollers if the feed system isn’t properly guarded.
Belts and pulleys shall be completely enclosed. Guards shall be used regardless of the location of the line shaft. The cutting heads shall be curved with a metal guard or cage. Barriers shall be at the loading and unloading sides to keep hands out of the point of operation. Guards shall be in place to prevent clothing, hair, and hands from being caught by and pulled into the automatic feed mechanism. Guard feed allows boards to pass but keep the operators fingers out.
- Stand to the side after starting boards through the planer
- Do not feed boards of different thickness without adjusting properly
- Wear eye protection
- Make sure planer is anchored to a solid foundation
This section covers the major hazards associated with saws and other tolls used in finishing wood stock. A variety of saws, shapers, sanders, drills, and pneumatic equipment are included. Engineering controls and work practices for minimizing exposure to these hazards are outlined.
Band saws use thin, flexible, continuous steel strips with cutting teeth on one edge. The blade runs on a driver and idle pulley and through a work table when stock is manually fed. The two types of band saws are horizontal and vertical. The operator is required to hand feed and manipulate the stock against the blade to saw along the line. The stock must be kept flat on the work table and the operator must exert the correct cutting pressure.
The most common operator injury is caused by contact with the blade. The blade should be guarded entirely except at the point of operation. A self adjusting guard should be used for the portion of the blade between the sliding guide and the ripper saw so it raises and lowers with the guide. The pulley mechanism should be fully enclosed. Feed rolls should be guarded. The saw should be equipped with a tension control device to indicate proper blade tension. The blade guide post should be adjusted to fit the thickness of the stock.
- Use a blade of the proper size and type
- Set the guard to just clear the stock when it is near the blade
- Use a jig when cutting small pieces of stock
- Use a push stick whenever possible
Scroll saws are used for precision cutting of curves and patterns. They have small thin blades that are held in upper and lower chucks that keep the blade tight. The blade moves rapidly up and down through the opening in the saw table.
Scroll saws are not as dangerous as most other saws. However, contact at the point of operation can cause hand and finger injuries. The portion of the blade below the table must be guarded.
Lathes are used for shaping parts. Automatic and manual feed lathes are used. In an automatic feed lathe the stock is mounted on a carriage and is moved into contact with multiple knife cutter head that runs the length of the stock. The stock rotates at low speed while the cutter rotates faster.
In a hand feed lathe the stock rotates rapidly while the operator applies a simple point tool to the wood. The operator holds the tool on the tool rest and advances it along the length of the rest to shape the stock.
The hazards associated with lathes are contact with rotating parts at the point of operation. Hands, clothing, or jewelry may be caught on the rotating parts and pulled into the machine. The hazard is greater with hand fed lathes because the operator is in close proximity to the rotating stock and the cutting tool.
For automatic lathes with rotating knives a metal shield or hood that completely covers the knives and stock except at the contact points must be in place when the machine is in operation. For manual lathes cover the cutter heads as completely as possible with the shield or hood. For lathes used for turning long stock; long stock guards should be present which would prevent the stock from being thrown from the machine should the stock come loose. The power transmission should be enclosed.
- Set the tool rest close to the stock
- Don not support the tool with your hands use the rest
- Make adjustments to the rest when the lathe isn’t running
- Never allow operators to wear loose clothing, long hair, jewelry, or gloves
- Do not use stock that has splits, cracks, or knots
- Allow glue joints to fully dry
- Hold tools firmly
Woodworking shapers are machines that are used to shape the edges of stock. Cutting occurs by hand feeding stock against a vertical rotating cutter mounted on a spindle. The cutting edges rotate at 7200 to 10000 rpm.
Operators should listen for chatter. This indicates the knives are out of balance. Knives must be balanced, properly fitted, and precision ground to minimize the possibility of being flung from the cutter head.
In order to lessen the potential of kickback double-spindle shapers shall have starting and stopping device for ach spindle. Automatic feed rollers should be guarded.
- Operators should not wear loose clothing, long hair, jewelry, or gloves
A drill press uses a rotating tool to produce a hole in stock. Normally drill presses are vertical and have variable speeds. Some may have multiple spindles for gang drilling. The most common machines are single spindle and belt driven.
The most common accident results when the operator attempts to hand hold the stock while drilling. When the drill enters or passes through stock it can catch and twist the stock which could result in an uncontrolled rotating piece of wood. Clamps or some type of hold-down fixture should be utilized.
As with most wood working machines flying wood chips are a hazard. Good housekeeping is essential when using a drill press. The work area must be kept clear of debris.
Power transmission components should be enclosed for machines that have adjustable belt drives. Automatic and high production machines should use barricades or enclosures to separate the operator from the drilling machine.
Sanders finish stock by using a coated abrasive surface to remove material. The three general types of sanders are drum, Belt, and disc. Sanders produce a considerable quantity of wood dust. Controls and hazards of wood dust are addressed in a separate topic. The major safety hazard associated with belt sanders is that operators may catch their hand, clothing, or jewelry in the in running rolls. Contact with the abrasive surface may cause abrasions and lacerations.
On automatic sanders feed rolls should be guarded to prevent operator contact. The guard design must allow for adjustment to any thickness of stock. The unused sum of the sanding belt should be guarded to prevent accidental contact. Drum and disc sanders should be enclosed with guards except for the portion of the 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. Power transmission pulleys should be enclosed with a fixed guard.
- Keep hands away from abrasive surfaces
- Sand on the downward moving side of the disc or belt
- Replace torn, frayed, worn or damaged belts or drums
Routers are used for cutting and shaping decorative pieces, making frame and panel doors and milling mouldings. Routers have spindles that spin variously shaped small diameter cutting tools at high speeds. The cutting tool is held in a collet chuck and protrudes through a flat, smooth bace that slides on the surface of the wood. The spindle is driven by belts and pulleys or by a high speed motor.
Inadvertent conduct with the cutting head when handling stock or removing scrap from the table is the most likely cause of injuries. For stationary routers the tool should be enclosed with an adjustable guard. Feed rolls should also be guarded.
- Operators should not wear loose clothing, long hair, jewelry, or gloves.
- Use cutting tools at the proper spindle speed.
- Feed stock in the proper direction.
- Use good quality stock that is unlikely to break.
Tenoning machines use cutter heads or saw blades to cut projections (tenons) on pieces of stock. Each tenon can be inserted into a cavity (mortise) or another piece of wood to form a mortise and tenon joint.
For stationary machines guarding is utilized to prevent operator contact with the cutter head or saw blade. Feed chains and sprockets shall be enclosed except for the portion of the chain conveying stock. The cutting heads and blades should be guarded to prevent operator contact.
Mortising machines use cutter heads or chains to cut cavities into a piece of wood. Generally a tenon is inserted to make a mortise and tenon joint.
To lessen the possibility of operator contact with the boring bit or mortising chain a number of guards are used. The boring bits should be enclosed with a guard that covers the bit and chuck above the material being worked. Operating treadles should be covered with U-shaped guards to prevent accidental tripping. The top of the cutting chain and driving mechanism should be enclosed. Safety bit chucks with no projecting screws should be used.
Handheld Production Tools
Handheld production tools include sanders, jigsaws, routers, drills, circular saws and pneumatic nailers /staplers. Typically handheld tools are not as inherently dangerous as larger stationary tools of the same type. However potential hazards related to handheld tools do exist and cause more injuries than their larger stationary cousins.
Handheld sanders finish stock by using a coated abrasive surface to remove material. A belt sander uses a system of pulleys to move the abrasive across the stock. Typically the sanding belt is pressed toward the wood which is located on a work table. Orbital sanders operate in the same manner but utilize a disk rather than a belt.
Abrasion injuries may occur when the operator’s hands contact the abrasive material. The moving parts of the sander should be enclosed to prevent fingers from coming into contact with nip points.
- Worn or frayed belts or disks should be replaced.
Jigsaws are useful for precision cutting of intricate curves and patterns on thin stock. The thin blades move rapidly up and down. A hold down adjusts to the thickness of the material being cut.
Jig saws are not considered as dangerous as many other saws. However, contact with the blade at the point of operation can cause injuries. The blade should be guarded.
- Make turns slowly.
- Use a narrower blade for sharp turns.
Routers are used for cutting and shaping, making frame and panel doors and milling mouldings. Routers have spindles that turn variously shaped small diameter cutting tools at high speeds. The bit is made of steel or carbide. It is held in a collet chuck and protrudes through a flat smooth base that slides on the surface of the work. Routers may be used in conjunction with a router table.
The most serious injury occurs when the operators hand contact the cutting bit. As much guarding as possible should be utilized.
- Never start routing at the end grain.
- Increase speed to prevent kickbacks.
A drill uses a multiple cutting edged rotating tool to cut a hole in the stock. Normally drills have variable speeds.
One of the most common accidents occurs when the operator attempts to hand hold stock while drilling. When the drill enters the stock it can catch and twist the stock from the operator. The result is an uncontrolled piece of wood. Guarding is especially difficult because of the nature of the tool. Whenever possible a hold down apparatus should be used rather than the hands.
Circular saws are used for strait sawing. They can be used for crosscutting or rip sawing.
Injuries can occur if the operator’s hands slip while cutting stock or if they are in the line of cutting. Kickbacks are another major cause of injuries. They are more likely to occur when ripping or cutting poor quality lumber. When ripping, a spreader should be used to prevent material from squeezing the blade or kicking back during ripping. If the saw kicks back anti-kickback fingers should be used to hold down the stock.
- Use the proper blade for the cutting being performed.
- Properly support stock.
- Operate saw at proper speed.
- Maintain and sharpen blades.
- Remove damaged blades from service.
Pneumatic Nailers /Staplers
To prevent injuries the nailer/stapler must be equipped with a device to keep fasteners from being ejected unless the muzzle is pressed against the work surface. A positive locking device attaching the air hose to the tool should be utilized. If an air hose greater than ½ inch in diameter is used a safety excess flow valve should be installed at the source of the air supply to reduce pressure in the event of hose failure.
Exposure to wood dust is associated with a variety of adverse health effects. Contact with the irritant compounds in wood sap can cause dermatitis and other allergic reactions. The respiratory effects of wood dust exposure include asthma and bronchitis. Treated wood dust may contain toxic chemicals.
The OSHA exposure limit for nuisance dust is 15mg/m3. A level of 0.5mg/m3 has been recommended for western red cedar based on its asthma effects. Some species of hardwood such as oak, mahogany, beech, walnut, birch, elm, and ash have been reported to cause nasal cancer.
The primary method of controlling wood dust is local exhaust ventilation. Exhaust collection ports should be located as close as possible to the emission source. For local exhaust ventilation systems to provide protection they must be properly maintained. The system should be periodically cleaned, inspected, and repaired as necessary. Sanders, shapers, and routers produce the greatest amount of dust. Collection of dust for these and other tolls can be difficult. Keeping dust and debris cleaned goes a long way in limiting dust exposure.
Noise levels can be a significant problem in the workshop. There are three basic approaches toward controlling noise. These include source control, path control, and hearing protection. Source controls provide the most effective means of noise reduction and are therefore the preferred methodology.
Source control begins with an analysis of the noise generating equipment. All noise sources within a piece of equipment as well as the ways in which the noise is transmitted should be identified. Sources generally include motors, gears, belts, pulleys, points of operation, and any moving parts. Transmitters include frames, footings, and equipment housings.
To reduce noise levels at the source a member of methods may be used. Motors and all moving parts should be maintained in very good condition. Maintenance involves lubricating and cleaning, replacing worn parts, maintaining proper belt tension, bolt torque, and properly balanced pulleys, blades, and rotating parts. The speed of operation of the equipment should be as slow as possible which is consistent with product quantity and quality goals. Equipment frames should be as rigid as possible. The equipment should be firmly seated on a solid floor. Equipment should not be in contact with other equipment or walls. Noisy equipment should be isolated with rubber footings or springs. Vibration damping materials should be applied to all resonating surfaces.
Path controls involve isolating or reducing noise intensity before it reaches personnel ears. There are three basic ways to do this. Operations may be segregated to limit the number of individuals exposed to excessive noise. Equipment may be enclosed with barriers designed to absorb or reflect noise. Moving noise producing equipment away from people is the most effective method.
Hearing protection protects the ear from harmful noise. They should be worn as the final defense against noise hazards. EHS can perform a workplace noise survey to determine the level of exposure. Levels above 85 dBA require a hearing conservation program. More information regarding hearing conservation is available on the EHS website.
Hand help and stationary tools that transmit vibration through a work piece can cause problems. Raymond’s syndrome is a disease of the hands and feet in which the blood vessels collapse. It can be caused by repeated exposure to vibration. The skin and muscles do not get the oxygen needed and eventually die. Hand-arm vibration syndrome (HAVS) is a more advanced condition that may affect the entire hand or arm. Early signs of HAVS are feelings of numbness and/or tingling in the fingers, hands or arms, or numbness and whiteness in the tips of the fingers when exposed to cold. As the disease progresses a person’s experiences more frequent and severe attacks of numbness and pain and it may become difficult to use their hands. Advanced HAVS may disable a person for a long time.
Engineering controls are the best way to limit exposure to vibration. Vibration isolators or dampening techniques on equipment offer the best effective protection. Felts, liquid mastics and elastomeric dampening sheets are effective dampening material. Determining the correct type and quantity of dampening material to use for a particular machine is a complicated process and should be done by a safety professional. The frequency emitted by the machine, the vibration reduction level desired and the weight and size of the machine are factors.
A number of work practices may be utilized. Machines should be maintained in good working order. Unbalanced, rotating parts or unsharpened cutting tools may give off excessive vibration. Work tasks may be arranged so vibrating and non-vibrating tools are used alternatingly. The hours that a vibrating tool is used can be restricted. Employees should have a 15 minute task break from the vibration source each hour. All exposed personnel should be trained regarding the hazards of working with vibrating tools. Training should include instruction regarding sources of vibration, early signs and symptoms of HAVS and ways of minimizing vibration exposure.
Electrical components in a woodworking facility are a significant hazard. Safety precautions should be followed otherwise serious injury or death could result.
All of the metal framework on electrically driven machines must be grounded. This includes the motor, casing, legs, frame, and lights that may be mounted on the machine. Circuit breakers and fuse boxes must be labeled to indicate what areas/equipment is served. Appropriately rated fuses and circuit breakers must be used. Unused slots in electrical boxes must be covered. All electrical components must be approved by a nationally recognized testing laboratory. All machines should have a main power disconnect. Lockout/tagout procedures should be used. Machines should not automatically restart after a power failure. An emergency stop should be within reach of the operator working in the normal operating position. Controls should be clearly marked and within easy reach of the operator.
Each year thousands of employees are injured while repairing or maintaining machines. Workers may be injured at the point of operation, drawn into moving part, electrocuted, or suffer crushing injuries.
All power sources including electrical, mechanical, pneumatic, and hydraulic must be shut off and locked/tagged out during maintenance. The elements of the UA lockout/tagout plan should be followed. This includes identifying power sources, and the correct procedure for shutting down, testing, and re-energizing the equipment.
Fire and Explosions
Wood working shops are a significant fire and explosion risk. They typically contain large quantities of fuel and flammable materials. They also have ignition sources such as electrical wiring, electrical motors, sparking tools, cutting and welding operations. Preventing the buildup of sawdust is one of the key elements for controlling fire and explosion hazards. The principal engineering control of sawdust is exhaust ventilation. Dust collection is accomplished at the source. Good housekeeping is essential. Periodically the entire work shop should be cleaned to remove dust that will accumulate in out of the way areas. It is also very important to inspect and clean the exhaust ventilation system. Never blow accumulated dust with compressed air while ignition sources are present.
Storage and segregation are also vital elements of reducing the possibility of fire and explosion. Flammable materials such as paint, finishes, adhesives, and solvents should be stored in proper primary and approved secondary containers. Combustible and flammable materials such as wood stock and chemicals should be segregated from each other and ignition sources. Tasks that are prone to fire and explosion hazards such as spray painting, welding and cutting should be separated from other work.
Most problems related to the assembly of materials are related to ergonomics. About 25% of the accidents reported in industry each year are associated with the manual handling and assembly of stock and production wood. Ergonomics is the study of the relationship between the worker and the work environment. Musculoskeletal stress and repetitive motion are the greatest concerns. All of the assembly process should be studied to determine if certain processes can be made less stressful on the joints and musculoskeletal frame. Repetitive motions can be especially damaging and should be eliminated whenever possible.
Finishing operations present a wide range of health and safety hazards due primarily to the volume and physical properties of the chemicals involved. The specific chemicals in use should be identified and the hazards evaluated. Engineering controls should be used to reduce potential exposure to acceptable levels.
Chemicals enter the body through inhalation, ingestion or skin contact. People working in wood shops are generally exposed through inhalation or absorption. Lacquers and varnishes contain toxic solvents. The most common solvents are toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone and methanol. Many varnishes contain formaldehyde. All of these solvents have short term effects such as irritation of the eyes, nose and throat, headaches, dizziness, confusion, fatigue and nausea. Long term effects include damage to the lungs, liver, kidneys, reproductive and central nervous systems.
Many of the adhesives used in finishing wood products also contain toxic chemicals. The most hazardous are epoxy resin and urea-formaldehyde resin adhesives. Epoxy resin adhesives are particularly toxic. Some of the components may be carcinogenic and may also cause dermatitis and sensitization.
In addition to the health hazards posed by the chemicals many are extremely flammable. These materials can pose significant fire and explosion hazards if used in large quantities, in unventilated or enclosed areas or in processes such as spray finishing which can create large airborne concentrations.
Engineering controls are the preferred method of eliminating exposures to hazardous contaminants or conditions. When finishing wood with coating and adhesives; try to use materials that are less toxic. Adequate ventilation should be provided for all coating and gluing processes; which includes spraying, rolling, brushing, automated coating processes and dip coating. Open surface tanks used for dip coating should be ventilated with an enclosure or hood. Spray booths should be used whenever possible for the application of spray coatings. The requirements for air flow and make up air are very specific. Excessive air pressure decreases efficiency and may cause a backlash of vapors and over spraying into adjacent areas. Dirty air filters decrease air flow in the booth and must be cleaned or replaced periodically.
Failure to provide employees and users with information and training related to hazardous chemicals is one of the most frequently cited regulatory violations. EHS has developed a comprehensive Hazard Communication Program. The three major components are safety data sheets, training and labeling. Safety data sheets provide information on the chemical constituents that make up a material. Manufacturers must provide safety data sheets and these shall be available to employees and users. Employees and users must be trained regarding the hazards of the chemicals they work with. Container labels must include information about the contents and their associated hazards.
Personal protective equipment (PPE) includes respiratory equipment, gloves, boots, safety glasses, coveralls and other clothing or equipment that may be necessary to protect users. PPE cannot be used instead of engineering controls. Engineering methods such as ventilation are the first step to control exposures and limit hazards. PPE is used to augment engineering controls.