Abrasive wheel. A grinding tool consisting of bonded abrasive grains. This includes diamond and reinforced wheels.

Blind hole. A hole drilled in an object, such as an abrasive wheel, that does not go all the way through.

Blotter. A compressible disc or washer, usually of blotting paper, plastic, cardboard, or gasket material, that is used between the wheel and the flanges to evenly distribute flange pressure on the wheel.

Cone and plug wheels (Types 16, 17, 18, 18R, and 19). Abrasive wheels manufactured with blind hole threaded bushings. They may be used on all surfaces except the flat mounting surface (D). Specific characteristics of the different cone and plug wheels are:

(a) Type 16 cones have a curved side with a nose radius;

(b) Type 17 cones have straight sides with or without a nose radius;

(c) Type 18 and 18R plug wheels are cylindrical in shape with either a square or curved grinding end;

(d) Type 19 cone wheels are a combination of cone and plug shapes.

Cutting-off wheels. Abrasive wheels used to cut material such as masonry, pipe, etc.

Designated person. A person selected or assigned by the employer or the employer's representative as competent to perform specific duties.

Discharge opening. An opening in a mower housing for discharging grass.

Flanges. Collars, discs, or plates between or against which wheels are mounted. There are four types of flanges:

(a) Adaptor;

(b) Sleeve;

(c) Straight relieved;

(d) Straight unrelieved.

Grass catcher. Parts or a combination of parts to collect grass clippings or debris.

Guard (abrasive wheels). An enclosure designed to restrain the pieces of an abrasive wheel and furnish protection to the operator if the wheel is broken during operation.

Guard. A part or assembly to prevent accidental contact with hazardous machine parts or to protect persons from other hazards created by the machinery.

Inorganic bonded wheel. Abrasive wheels that are bonded by means of inorganic material such as clay, glass, porcelain, sodium silicate, magnesium oxychloride, or metal.

Jack. A portable hand- or power-operated mechanism for lifting, lowering, or moving horizontally a load by applying a pushing force.

Modified Types 6 and 11 wheels (terrazzo). Similar to Type 6 "straight cup" wheels and Type 11 "flaring cup" wheels except for the bottom of the cup. The bottom of the cup is flat in Type 6 and 11 wheels. The modified wheels have bottoms that are sloped downwards towards the mounting hole. These modified wheels need to be mounted using a special tapered flange furnished by the tool manufacturer. These wheels are used in the terrazzo trade.

Mounted wheels. Bonded abrasive wheels of various shapes, usually two inches diameter or smaller, that are secured to plain or threaded steel mandrels.

Normal service (jacks). Raising or lowering axial loads that are eighty-five percent or less of the rated load under controlled conditions.

Organic bonded wheels. Abrasive wheels that are bonded by means of organic material such as resin, rubber, shellac, or other similar bonding agent.

Rated load. The maximum load that the jack is designed to lift or support.

Reinforced wheels. Organic bonded abrasive wheels which have webbing, fabric or filament to provide resistance to complete breaking of the wheel should it become cracked or damaged.

Terrazzo. A material of stone chips, such as marble, set in mortar and polished.

Threaded hole wheels. Abrasive wheels that have one central threaded bushing, securely anchored in place. They are mounted by being screwed onto a threaded machine spindle so that the wheel back seats firmly against an unrelieved flat back flange.

Tuck pointing wheels. Tuck pointing abrasive wheels are Type 1 reinforced, organic bonded wheels and have diameter, thickness and hole size dimensions. They are used to remove cement, mortar, or other nonmetallic jointing material.

Type 1 wheel. An abrasive wheel shaped like a disc with a mounting hole in the middle. Sometimes called a "straight wheel." It has diameter (D), thickness (T), and hole size (H) dimensions. Grinding is normally done on the periphery (outside curve) of the wheel (T dimension). Can be used for grinding, cutting-off, and tuck pointing.

Type 2 wheel. An abrasive wheel shaped like an open-ended, hollow cylinder. Sometimes called a cylinder wheel. It has diameter (measured from the outer wall of the cylinder), wheel thickness (height of the cylinder), and rim thickness (thickness of the cylinder wall). Grinding is done on the end of the cylinder (rim thickness dimension).

Type 6 wheel. An abrasive wheel shaped like a straight-sided cup or bowl with a mounting hole in the bottom of the cup. Sometimes called a "cup wheel." It has diameter (D), thickness (T), hole size (H), rim thickness (W), and back thickness (E) dimensions. Grinding is normally done on the cup rim (W dimension).

Type 11 wheel. An abrasive wheel shaped like a cup or bowl with a mounting hole in the bottom of the cup. The sides of the cup are not straight-sided but are angled outward. Sometimes called a "flaring cup wheel" since the sides are "flared" out. It has double diameter dimensions (top D and bottom J). It also has thickness (T), hole size (H), rim thickness (W), and back thickness (E) dimensions. Grinding is normally done on the cup rim (W dimension).

Type 16, 17, 18, 18R, and 19 wheels. See cone and plug wheels.

Type 27 wheel. An abrasive wheel similar to a Type 1 wheel, but the center of the wheel around the mounting hole is pushed back (depressed). Sometimes called a "depressed center" wheel. It has diameter (D), thickness (U) and hole size (H) dimensions. The depressed center allows grinding on the flat surface of the wheel without interference from the flange or mounting hardware.

Type 27A cutting-off wheel. Similar to a Type 27 wheel. Specifically designed for use on cutting-off machines.

Type 28 wheel. An abrasive wheel similar to a Type 27 wheel, but the face of the wheel is angled upward and away from the mounting hole. The face of a Type 27 wheel is flat and perpendicular to the mounting hole. A Type 28 wheel is also called a "depressed center" wheel. It has diameter (D), thickness (U), and hole size (H) dimensions. The depressed center allows grinding without interference from the mounting. A Type 28 wheel has a saucer-shaped grinding rim and is designed for corner grinding and side grinding.

Type 29 wheel. An abrasive wheel that has reversed, saucer-shaped grinding rims (similar to a partially opened umbrella).

This chapter applies to the tools and equipment shown in Table 1, Scope of this chapter.

Make sure hand-held portable power tools have safe switches (controls).

(1) You must make sure the operating switch is located in a position that makes it difficult to accidentally operate the tool.

(2) You must use the correct operating switch.

(a) Make sure hand-held gasoline-powered chain saws have a constant pressure throttle control that will shut off power to the chain when the pressure is released.

(b) Use a constant pressure switch that will shut off the power when the switch is released to turn on or operate any hand-held power tool.

Some tools can use a lock-on feature with the constant pressure switch if the lock-on feature can be turned off with a single motion of the same finger(s) that turned it on. You can use a lock-on feature with these hand-held tools:

1. Drills;

2. Tappers;

3. Fastener drivers;

4. Grinders using a wheel greater than two inches in diameter;

5. Disc sanders;

6. Belt sanders;

7. Reciprocating saws;

8. Saber, scroll and jig saws using a blade with a shank width greater than one-quarter inch;

9. Other similarly operating powered tools.

You can use a positive "on-off" switch with these hand-held tools:

1. Platen sanders;

2. Grinders using a wheel two inches or less in diameter;

3. Routers;

4. Planers;

5. Laminate trimmers;

6. Nibblers;

7. Shears;

8. Saber, scroll, and jig saws using a blade with a shank width of one-quarter inch (± .05 inch) or less.

Make sure portable circular saws are safe.

(1) You must use a constant pressure switch to turn on or operate any circular saw using a blade that has a diameter greater than two inches.

(2) You must remove cracked saws and saw blades from service.

(3) You must make sure power driven circular saws that have a blade diameter larger than two inches have guards above and below the base plate (shoe) as listed in Table 2, Portable circular saw guarding requirements.

Make sure portable belt sanding machines are safe.

(1) Nip points where the sanding belt runs onto a pulley;

(2) The unused run of the sanding belt.

This section applies to portable, hand-held compressed air powered tools. It also applies to airhose and plastic pipe used to supply compressed air to these tools.

Make sure compressed air and compressed air tools are used safely.

You must make sure a tool nozzle or an airhose opening is not:

(1) Pointed at anyone;

(2) Allowed to contact a person's body.

You must use the following when cleaning with compressed air:

(1) Air pressure that has been reduced to less than 30 p.s.i. static pressure at the nozzle;

(2) Effective chip guarding.

(1) You must make sure the airhose and hose connections are suitable for the:

(a) Air pressure;

(b) Use.

(2) You must make sure any plastic pipe used to supply compressed air for portable air tools has been specifically identified by the manufacturer as being suitable for compressed air use.

This section does not apply to:

1. Tools specifically for medical or dental use;

2. Tools specifically for use in the food processing industry;

3. Tools mounted in stationary installations;

4. Air hoists;

5. Construction and mining tools such as paving breakers, diggers, tampers, and rock drills.

You must make sure portable, hand-held air tools meet the requirements of:

(1) ANSI B186.1-1984, Safety Code for Portable Air Tools; or

(2) ANSI/ISANTA SNT-101-1993, Portable, Compressed-Air-Actuated, Fastener Driving Tools-Safety Requirements for.

This section does not apply to:

1. Tools specifically for medical or dental use;

2. Tools specifically for use in the food processing industry;

3. Tools mounted in stationary installations;

4. Air hoists;

5. Construction and mining tools such as paving breakers, diggers, tampers, and rock drills.

(1) You must relieve the pressure in the air line before disconnecting a compressed air tool from the line or disconnecting a hose joint unless there is automatic valve closing protection at the joint being separated.

(2) You must disconnect the tool from the compressed air supply before repairs are done.

(3) You must make sure that eye protection is worn at all times by:

(a) The person operating the tool;

(b) Other persons in the area where tools are being used.

(1) You must make sure any fastener driving air tool discharges all air in the tool when disconnected from the compressed air supply.

(2) You must make sure that all pneumatically driven nailers, staplers, and other similar equipment provided with automatic fastener feed have a safety device on the muzzle to prevent the tool from ejecting fasteners, unless the muzzle is in contact with the work surface.

This section applies to any powder actuated fastening system designed to use the expanding gases from a powder load to propel a stud, pin, fastener, or other object into hard structural material.

This section does not apply to:

1. Devices designed to attach objects to soft construction material such as wood, plaster, tar, and dry wallboard;

2. Stud welding equipment.

Make sure powder actuated fastening systems are used safely.

(1) You must make sure tools are used only by qualified operators.

(2) You must make sure operators have been trained by an authorized instructor.

(3) You must make sure all tool operators can:

(a) Understand the manufacturer's instructions;

(b) Clean the tool properly;

(c) Recognize any visibly worn or damaged parts;

(d) Identify power load levels;

(e) Operate the tool correctly.

(4) You must make sure tool operators have a valid qualified operator's card in their possession when they are using the tool.

(1) You must make sure eye or face protection is worn by:

(a) Tool operators;

(b) Assistants;

(c) Persons close to where the tool is being used.

(2) You must post signs where tools are being used and in adjacent areas where tool use could pose a hazard. Signs must:

(a) Be easily seen;

(b) Be at least 8 x 10 inches (20 x 25 cm);

(c) Use letters in boldface type at least one inch (2.5 cm) high;

(d) Read "powder actuated tool in use" or similar wording.

(1) You must make sure the tool meets the design and construction requirements of the American National Standards Institute (ANSI) standard ANSI A10.3-1995, Safety Requirements for Powder-Actuated Fastening Systems.

(2) You must make sure each tool has:

(a) Operator instructions and a tool service manual;

(b) Powder load and fastener chart;

(c) Service tools and accessories.

(1) You must make sure tools are properly labeled.

(2) You must make sure each tool has a readable, permanent label that shows the manufacturer's:

(a) Model number.

(b) Unique serial number.

(3) You must make sure there is a durable warning label on each tool that:

(a) Reads "warning - for use only by qualified operators according to manufacturer's instruction manual"; or

(b) Uses words with the same meaning.

(4) You must make sure the tool storage container has these labels:

(a) "powder actuated tool" on the outside of the container in an easily seen position.

(b) "warning - powder actuated tool. to be used only by a qualified operator and kept under lock and key when not in use" on the inside cover.

You must make sure powder loads and power levels are identified as specified in Table 3, Powder-Load Identification

You must use only a powder load that is:

(1) Recommended by the tool manufacturer for the particular tool; or

(2) One that provides the same level of safety and performance.

(1) You must use the lowest velocity class of tool and load that will properly set the fastener.

(2) You must use the proper shield, fixture, adaptor, or accessory that is:

(a) Suitable for the job;

(b) Recommended and supplied by the manufacturer.

(1) You must make sure the operator:

(a) Inspects the tool before using it, as recommended by the tool manufacturer;

(b) Uses the tool according to the manufacturer's instructions;

(c) Keeps the tool unloaded until just before using it;

(d) Unloads the tool at once if work is interrupted after the tool has been loaded;

(e) Does not leave a tool or powder load unattended where it would be available to an unauthorized person;

(f) Never points a tool (loaded or unloaded) at any part of a person's body.

(2) You must make sure tools are not used in an explosive or flammable atmosphere.

(3) You must do this if the tool misfires:

(a) Hold it firmly against the work surface for thirty seconds; then

(b) Follow the instructions in the tool manufacturer's instruction manual.

(4) You must hold the tool perpendicular to the work surface when fastening to any material.

This does not apply if the tool manufacturer recommends a different technique for a specific job.

(1) You must use fasteners:

(a) Recommended by the tool manufacturer for the particular tool; or

(b) Fasteners that provide the same level of safety and performance.

(2) You must keep the fastener from passing completely through the structural material by using a backing material when driving a fastener into any material that is any of the following:

(a) Easily penetrated;

(b) Thin;

(c) Of questionable resistance.

(3) You must make sure the material is suitable for fastening. Do not drive fasteners into very hard or brittle material such as:

(a) Cast iron;

(b) Glazed tile;

(c) Hardened steel;

(d) Glass block;

(e) Natural rock;

(f) Hollow tile;

(g) Most brick.

(4) You must make sure positive alignment with an existing hole is maintained by using a guide or other means supplied or recommended by the tool manufacturer before driving a fastener into the hole.

(5) You must make sure fasteners are not driven into any spalled (chipped or crumbled) area.

(6) You must drive fasteners into concrete only if the fastener shank will penetrate no more than one-third the thickness of the concrete.

(7) You must make sure fasteners are driven at least:

(a) One-half inch (13 mm) from the edge of steel;

(b) Three inches (75 mm) from the unsupported edge of masonry material.

This does not apply if an application is specifically required or recommended by the tool manufacturer.

(1) You must make sure any tool that is not in proper working condition is:

(a) Immediately removed from service;

(b) Tagged;

(c) Properly repaired as specified in the manufacturer's instructions before being used again.

(2) You must regularly service the tool and inspect it for worn or damaged parts at intervals recommended by the tool manufacturer.

(3) You must replace worn or damaged parts before the tool is used. This must be done:

(a) By a qualified person;

(b) Using only parts supplied by the tool manufacturer.

(4) You must keep a written record of inspection dates.

(1) You must make sure there is a container that can be locked for each tool.

(2) You must make sure tools and powder loads that are not being used are:

(a) Locked in a container;

(b) Stored in a safe place;

(c) Only available to authorized persons.

(3) You must store all manuals, maintenance tools, and accessories in the tool container when they are not being used.

This section does not apply to commercial equipment that is:

1. Designed primarily for agricultural purposes; or

2. Designed primarily to be operated with tractors having at least twenty horsepower for cutting grass or other growth on highways.

Make sure power lawnmowers are used safely.

(1) You must make sure equipment meets ANSI design and construction requirements.

(a) Make sure power lawnmowers manufactured on or after August 1, 2003, meet the requirements of the appropriate ANSI standard:

(i) ANSI B71.1-1998, American National Standard for Consumer Turf Care Equipment - Walk-Behind Mowers and Ride-On Machines with Mowers - Safety Specifications; or

(ii) ANSI B71.4-1999, American National Standard for Commercial Turf Care Equipment - Safety Specifications.

(b) Make sure noncommercial power lawnmowers manufactured before the effective date of this chapter meet the requirements in chapter 296-806 WAC, Machine safety.

(2) You must position, guard or shield all power-driven shafts, chains, belts, gears, friction drive components, nip and pinch points, and any exposed components hot enough to cause burns while:

(a) Starting;

(b) Mounting;

(c) Operating the machine.

(3) You must have a shutoff device that:

(a) Will stop the motor or engine; and

(b) Has to be intentionally and manually activated before the motor or engine can be restarted.

(1) You must make sure all positions of the operating controls are clearly identified.

(2) You must make sure warning and caution labels or decals on the mower are readable and replace them if necessary.

(1) You must make sure the operator understands all instructions for operating the mower that are in the manufacturer's instructions and on the machine.

(2) You must make sure the operator is thoroughly familiar with the controls and proper use of the mower before starting it.

(3) You must make sure the proper guards, plates, grass catcher or other safety devices are in place before starting the mower.

(1) You must follow the manufacturer's instructions for safe use of the equipment.

(2) You must keep people clear of discharge opening(s).

(3) You must keep people's hands and feet clear of rotating parts.

(4) You must clear the area of objects such as rocks, toys, wire, bones, sticks, etc., which could be picked up and thrown by the blade and create a hazard for the operator or other persons.

(5) You must make sure the operator stops the engine before:

(a) Leaving the equipment;

(b) Unclogging the grass discharge chute;

(c) Cleaning the mower.

(6) You must make sure the operator wears safety goggles or safety glasses with side shields when operating the mower.

This section does not apply to electric engines.

(1) You must make sure to:

(a) Keep the gas cap on whenever the engine is running.

(b) Shut off the engine before and during refueling.

(2) You must make sure not to refuel the machine indoors.

(3) You must make sure not to run the engine in a closed area.

You can refuel the machine indoors or run the engine in a closed area if the area was specifically designed for such use.

(1) You must make sure the operator wears substantial footwear when operating a walk-behind mower.

(2) You must mow across the face of a slope.

(1) You must make sure not to carry passengers.

(2) You must make sure the operator looks down and behind before and while moving backwards.

This section applies to portable hand- or power-operated:

(1) Hydraulic jacks;

(2) Mechanical ratchet jacks;

(3) Mechanical screw jacks.

Make sure jacks are safe to use.

You must make sure the rated load(s) of the jack is:

(1) Readable;

(2) Durably marked in an easily seen location on the jack.

(1) You must visually examine the general condition of the jack before each use.

(2) You must make sure the weight to be lifted or supported is within the rated load of the jack.

(3) You must make sure the base of the jack is on a firm foundation or blocked before lifting the load.

(4) You must make sure hydraulic jacks exposed to freezing temperatures function properly at the temperature they will be used.

(1) You must place a block between the load cap and the load if the load could slip off the jack.

(2) You must secure the load from falling or slipping immediately after it is raised by one or more of the following:

(a) Cribbing;

(b) Blocking;

(c) Some other equally effective method.

(3) You must make sure you do not exceed the limit of travel of the jack.

(1) You must inspect jacks at appropriate intervals:

(a) Make sure frequent inspections are done by the operator or other designated person as follows:

(i) Before a jack is first placed in service;

(ii) Monthly for a jack used in normal service;

(iii) Daily or before each use for a jack used for other than normal service;

(iv) Before using a jack that has been altered, modified, or repaired;

(v) Before using a jack that has not been used in one year or more.

(b) Make sure a periodic inspection of the jack is done once a year.

(c) Inspect the jack using Table 4, Jack Inspection Requirements, during any frequent or periodic inspection.

(2) You must make sure a jack that is out of order is:

(a) Tagged;

(b) Not used until repaired.

(3) You must make sure a jack is properly lubricated at regular intervals.

This section applies to portable tools using abrasive wheels.

This section does not apply to machines using:

1. Natural sandstone wheels;

2. Pulpstone wheels;

3. Coated abrasive products;

4. Loose abrasives.

Make sure abrasive wheel tools and wheels are safe to use.

You must make sure abrasive wheels and tools meet the design and construction requirements of:

(1) American National Standards Institute (ANSI) B7.1-2000, Safety Requirements for the Use, Care and Protection of Abrasive Wheels; or

(2) ANSI B186.1-1984, Safety Code for Portable Air Tools.

(1) You must use abrasive wheels only on machines that have safety guards.

(2) You must make sure the safety guard:

(a) Is mounted so it maintains proper alignment with the wheel;

(b) Is mounted with fasteners strong enough to keep the guard in position if a wheel breaks;

(c) Is positioned to deflect pieces of an accidentally broken wheel away from the operator;

(d) Covers the spindle end, nut, and flange projections.

Safety guards are not required on machines that use:

1. Wheels for internal grinding while advancing, retracting or within the work.

2. Mounted wheels two inches or less in diameter.

3. Types 16, 17, 18, 18R, and 19 cones and plugs and threaded hole pot balls where the work offers protection or the size does not exceed three inches in diameter by five inches long.

4. Notched, segmented, or continuous rim metal centered diamond lapidary wheels that are used with a coolant deflector and operated at 3,500 SFPM or less.

5. Type 1 wheels that are:

a. Two inches or less in diameter;

b. One-half inch or less thick;

c. Operating at peripheral speeds less than 1,800 SFPM;

d. Mounted on mandrels and used in portable drills.

6. Type 1 reinforced wheels that are:

a. Three inches or less in diameter one-quarter inch or less thick;

b. Operating at peripheral speeds of 9,500 SFPM or less;

c. Used by operators wearing safety glasses and face shields;

d. Valve seating grinding wheels.

(1) You must make sure safety guards are in good functional condition.

(2) You must replace any safety guard that:

(a) Is damaged, bent or severely worn; or

(b) Has been hit by parts from a breaking wheel.

You must make sure the safety guard covers the top and sides of the wheel for at least one hundred eighty degrees.

(1) You must make sure the safety guard:

(a) Covers the wheel's plane of rotation toward the operator for at least one hundred eighty degrees;

(b) Covers the side of the wheel toward the driving flange for at least one hundred eighty degrees;

(c) Has a skirt which is adjustable to within one-eighth inch of the plane of the surface of the wheel.

(2) You must make sure not to use a "revolving cup guard."

You must make sure safety guards:

(1) Cover the wheel's plane of rotation toward the operator for at least one hundred eighty degrees.

(2) Cover the side of the wheel toward the driving flange for at least one hundred eighty degrees.

(3) Have a lip on the outer edge that:

(a) Extends beyond the surface of the wheel throughout the one hundred eighty degree coverage; and

(b) Curls inward to deflect wheel fragments.

You must use a side handle on all four-inch and larger vertical and angle grinders.

(1) You must do the following before mounting a wheel:

(a) Visually inspect the wheel for cracks or damage;

(b) Perform a ring test for cracks (size and shape of the wheel permitting);

(c) Make sure the spindle speed of the machine is not greater than the operating speed of the wheel.

(2) You must make sure a damaged or cracked wheel is not mounted or used.

(1) You must make sure wheels fit freely on the spindle, wheel sleeves, or adaptors, and remain free under all grinding conditions.

(2) You must make sure wheel, blotter and flange surfaces that contact each other are flat and free of foreign particles.

(3) You must make sure any reducing bushing used in the wheel hole:

(a) Fits freely on the spindle and maintains proper clearance;

(b) Does not exceed the width of the wheel or contact the flanges.

(4) You must make sure that multiple wheels mounted between a single set of flanges are either:

(a) Cemented together; or

(b) Separated by spacers that have a diameter and bearing surface that is the same as the mounting flanges.

(1) You must mount all abrasive wheels between flanges that have a diameter at least one-third the diameter of the wheel.

This requirement does not apply to the following types of wheels:

1. Mounted wheels;

2. Cup, cone or plug wheels with threaded inserts or projecting studs;

3. Abrasive disc wheels (inserted nut, inserted washer and projecting stud type);

4. Plate mounted wheels;

5. Cylinder, cup, or segmental wheels mounted in chucks;

6. Types 27, 28, and 29 wheels;

7. Internal wheels less than two inches in diameter;

8. Modified Type 6 and 11 wheels (terrazzo);

9. Types 1 and 27A cutting-off wheels.

(2) You must make sure flanges are:

(a) Dimensionally accurate;

(b) Properly balanced;

(c) Flat;

(d) Free of rough surfaces or sharp edges.

(3) You must make sure, if a wheel is mounted between two flanges, that both flanges:

(a) Are the same diameter;

(b) Have equal bearing surfaces.

The following wheels do not require same diameter, equal bearing surface flanges:

1. Types 27, 28, and 29 wheels with adaptors;

2. Modified Types 6 and 11 wheels with tapered K dimension;

3. Internal wheels less than two inches in diameter.

(4) You must make sure the driving flange is:

(a) Part of the spindle; or

(b) Securely fastened to the spindle.

(1) You must make sure flange bearing surfaces are in good condition.

(2) You must replace or remachine any flange with a mounting surface that has any of the following problems:

(a) Warped;

(b) Burred on the bearing surface;

(c) Excessively worn (thickness or diameter);

(d) Out of true.

You must mount Type 1 cutting-off wheels between flanges that are:

(1) Properly relieved with matching bearing surfaces;

(2) At least one-quarter the wheel diameter.

You must mount Type 27A cutting-off wheels between flanges that are:

(1) Flat (unrelieved) with matching bearing surfaces;

(2) At least one-quarter the wheel diameter.

You must use a back flange to mount threaded hole wheels that is:

(1) Flat (unrelieved);

(2) Securely fastened and square to the spindle axis;

(3) Able to properly support the wheel.

You must mount cup, cone or plug wheels with threaded inserts or projecting studs against a straight, unrelieved flange.

(1) You must use a blotter between each flange and the abrasive wheel surface to uniformly distribute flange pressure.

(2) You must make sure the blotter covers the entire flange contact area.

(3) You must use a new blotter each time a wheel is mounted unless the wheel has a blotter already attached to it by the manufacturer.

(4) You must make sure scuffed or damaged blotters are not used.

You do not need to use a blotter with:

1. Mounted wheels;

2. Abrasive disc and Type 2 wheels which are mounted by inserted nuts, inserted washers, or projecting studs;

3. Plate mounted wheels;

4. Wheels mounted in chucks (such as cylinders and segmental wheels);

5. Types 27, 28, and 29 wheels;

6. Type 1 and Type 27A cutting-off wheels;

7. Internal wheels less than two inches in diameter;

8. Diamond and cubic boron nitride wheels with metal or carbon fiber cores.

You must mount modified Types 6 and 11 wheels (terrazzo) with a blotter applied to the flat side of the wheel only.