Machine Shop Safety Engineering Class Instructor: Mr. Leis Technology Education Department Baldwin High School

The Machine Shop Safety Lessons are offered only to students in Baldwin High School’s Engineering Course. If a student misses a lesson during the above mentioned instruction it will be their responsibility to schedule an appointment with the classroom teacher to make up any and all work missed during the class periods in questions. Students will not be able to operate any machines in 216 without having completed all classroom instruction time related to “Machine Shop Safety”. The classes will cover the following topics:

• The Baldwin High School Technology Education Department Safety Policy and safe operation of shop machinery, highlighting safety aspects of shop and location of important information.

• Fundamentals of lathe use, including facing, turning, drilling, tapping, and proper cleaning of machine tools.

• Fundamentals of mill use, including setting up a mill vise, side milling, face milling, drilling and proper cleaning of machine tools.

• Fundamentals of drill press use, including setting up & clamping materials to drill press table service, drilling and proper cleaning of machine tools.

• Fundamentals of vertical band-saw use, cutting materials and proper cleaning of machine tools.

• Fundamentals of horizontal band-saw use, cutting materials and proper cleaning of machine tools.

• Fundamentals of bench top grinder use and proper cleaning of machine tools. • Fundamentals of belt sander use and proper cleaning of machine tools.

These topics are covered in a series of modules. Students are required to complete the safety modules to obtain classroom shop privileges.

DRILL PRESS Drilling machines, or drill presses, are primarily used to drill or enlarge a

cylindrical hole in a workpiece or part. The chief operation performed on the drill press is drilling, but other possible operations include: reaming, countersinking, counterboring, and tapping.

The floor type drill press used in the Student Shop is a very common machine, found in both home and industrial workshops. This style drill press is composed of four major groups of assemblies: the head, table, column, and base. The head contains the motor and variable speed mechanism used to drive the spindle. The spindle is housed within the quill, which can be moved up or down by either manual or automatic feed. The table is mounted on the column, and is used to support the workpiece. The table may be raised or lowered on the column, depending upon the machining needs. The column is the backbone of the drill press. The head and base are clamped to it, and it serves as a guide for the table. The cast-iron base is the supporting member of the entire structure. PROCEDURE Successful operation of the drill press requires the operator to be familiar with the machine and the desired operation. The following are some good observations to follow when drilling a hole:

1. Prior to drilling a hole, locate the hole by drawing two crossing lines. Use a center punch to make an indentation for the drill point to aid the drill in starting the hole.

2. Select the proper drill bit according to the size needed. 3. Select an appropriate size center drill. 4. Select a cutting fluid. 5. Properly secure the workpiece to the table. 6. Select the correct RPM for the drill bit. Take into account: size of bit, material,

and depth of hole to be drilled. 7. Use an interrupted feed, called peck drilling, to break up the chips being

produced. 8. Pilot holes should be used on holes larger than 3/8” dia. Holes are to be

enlarged in no more than 1/4” increments. 9. Clean the drill press and surrounding area when finished.

TOOLING Drills-

A drill is a pointed cutting tool used for making cylindrical holes in the workpiece. It has helical flutes along its length for clearing chips from the holes. Drills are the most common used today, but there are many other styles with different purposes. A twist drill is composed of three major parts: a shank, body, and point. The shank is the part of the drill bit held in the spindle of the drill press. The drill press’ power is transferred through the shank. Shanks are either one of two styles, straight or tapered. Straight shank drills are held in a friction chuck. Slippage between the drill bit and the chuck is often a problem, especially for larger drills. When using drill bits larger than 1/2” dia., tapered shank drill bits are often used. These provide greater torque with less slippage than straight shank drill bits. The body, as described above, generally has two flutes to clear chips. These flutes are not cutting edges and should not be used for side cutting as an end mill. The point of the drill bit does all of the cutting action, which produces the cut chips. The point is ground on the end of the drill bit.

Holes produced by twist drill bits are generally oversize by as much as up to 1% of the bit’s dia. The accuracy of the hole is dependent on the following factors: size of the bit, accuracy of the bit’s point, accuracy of the chuck, accuracy and rigidity of the spindle, rigidity of the press, and rigidity of the workpiece in its setup. All holes to be drilled should be started with a centerpunch, centerdrill, or both. DRILL FORMATS

• Number sizes: #80 (.0135”) to #1 (.228”) • Letter sizes: A (.234”) to Z (.413”) • Fractional sizes: 1/64” (.0156”) upwards by 64ths/inch

Countersinks-

Countersinking is an operation in which a cone-shaped enlargement is cut at the top of a hole to form a recess below the surface. A conical cutting tool is used to produce this chamfer. When countersinking, the cutter must be properly aligned with the existing hole, and should be rotated about 1/3 the cutting speed of the drilling operation for the hole. Countersinking is useful in removing burrs from edges of holes, as well as providing a flush fit for flat-headed fasteners. Counterbores-

Counterboring is the process of cylindrically enlarging a hole part way along its length. A counterbore cutter is similar to a drill bit in that it has a shank and fluted body, but instead of a point, it has a smaller diameter pilot portion. The pilot fits into a pre-drilled hole, and guides the counterbore. Therefore the counterbore must be aligned with the original hole, so the pilot will follow the hole properly. Counterbores are used to accommodate studs, bolts, or socket head capscrews where a flush surface application is required. Tapping-

A tap is a tool used to cut internal threads in a cylindrical hole. A tap is fluted like a drill, but the flutes actually perform the cutting operation. The flutes extend the length of the threaded section and also serve to remove the chips being produced. The most common taps used are:

• The starting or tapered tap. This tap is used to start threads. At least the first six threads of this tap are tapered before the full diameter of the thread is reached.

• The plug tap. This is the general use tap, and is used to cut threads after the taper tap has been used and removed. Three to five of its first threads are tapered. This is the last tap used if the hole extends all the way through the workpiece.

Cutting fluids should always be used when tapping holes. It is also recommended

to advance the tap one full turn and the reverse it 1/4 turn to break the chip being formed. Always use a tap handle, not pliers or a crescent wrench to turn the tap. They can damage the tap, and the unequal torque provided can cause a thread to be cut poorly. SAFETY

The drill press can be a safe machine, but only as long as the student is aware of the hazards involved. Chips are produced in great quantities, and must be safety handled. The rotating chuck and cutter can also be a hazard. Develop safe working habits in the use of protective clothes, set-ups, and tools. The following rules must

be observed when working on any drill press in the Student Shop:

1. No attempt should be made to operate a drill press until you are certain you understand the proper procedures for its use.

2. Dress appropriately. Remove all watches and jewelry. Safety glasses or goggles are a must.

3. Plan out your work thoroughly before starting. 4. Know the location of the OFF button. 5. Clamp all work securely to the table. 6. Always remove the chuck key immediately after using it. A key left in the

chuck will be thrown out at a high velocity when the machine is turned on. Never let the chuck key leave your hand except to put it back into its holder.

7. Never stop a drill press spindle with your hand after you have turned off the machine. Chips often build up around the chuck.

8. Use a brush, not your hands, to remove chips from the machine. Do not clean up while the machine is running.

9. Remove burrs from drilled workpieces as soon as possible. 10. Keep the floor area clean. Immediately wipe up any oil spills.

MILLING MACHINES A milling machine is a power driven machine that cuts by means of a

multitooth rotating cutter. The mill is constructed in such a manner that the fixed workpiece is fed into the rotating cutter. Varieties of cutters and holding devices allow a wide rage of cutting possibilities.

The mills in the Student Shop are vertical milling machines, commonly called “Bridgeport” style mills. These versatile mills are capable of performing many operations, including some that are similar to those performed on the drill press like drilling, reaming, countersinking, and counterboring. Other operations performed on the mill include but are not limited to: side and face milling, flycutting, and precision boring.

Mills are classified on the basis of the position of their spindle. The spindle operates in either a vertical or horizontal position. The amount of horsepower the mill is able to supply to the cutter is also often important. MILL CONSTRUCTION

The vertical milling machine is made up of five major groups: base and column, knee, saddle, table, and head, (see figure). The base and column are one piece that forms the major structural component of the milling machine. They are cast integrally, ad provide the mill with its stability and rigidity. The front of the column has a machined face which provides the ways for the vertical movement of the knee. The knee supports the saddle and table. It contains the controls for raising and lowering the saddle. Sitting atop the knee is the saddle which supports the table. The saddle slides in dovetailed grooves into and away from the machine, providing the mill with its Y-axis movement. On top of the saddle sits the table. Being moved side-to-side, left-right, over the saddle furnishes the mill with its X-axis movement. The workpiece is secured to the table through the use of various types of holding devices. The head is the most complex assembly in the major parts groups. This contains the following components:

1. The drive motor and on/off switch. 2. Drive belt, gear train, and range lever selector. 3. Quill, spindle, and draw bar. 4. Quill feed, lock, and digital depth read out (Z-axis).

Vertical Milling Machine-Head

The spindle is located within and moved up or down by the quill. This is the Z-axis movement for plunge operations on the vertical mill. The quill is moved by the quill feed lever, and can be locked in place with the quill lock. Depth of plunge moves are measured with the electronic digital read out located on the front of the mill head. PROCEDURES

Proficiency in milling operations involves more than simply cutting metal. There are two main categories of procedures when machining on a milling machine: the preliminary operations, and the machining operations. Preliminary Operations- Cleaning-

The first, (and last), procedure in any machining operation. Without clean equipment and tools, the accuracy of the finished product diminishes quickly. The

accuracy, durability, and longevity of the equipment and tools depend on being kept clean. In today’s high tolerances in engineering, cleanliness is critical. Set-up-

For most jobs performed on a milling machine, setting up the workpiece is the most difficult, critical, and time consuming part of the job. The workpiece must not only be securely clamped, but held in such a way so that very surface to be machined will accurately align with other surfaces when finished. Several types of holding devices are used in mounting the workpiece o the milling machine. The most common used in the Student Shop are the vice, table clamps, index chuck, and rotary table. The vice is probably the most widely used fixture. There are two configurations for the vise. The plain vise, which rests with the jaws parallel to the X-axis. The second style is with the swivel-base mounted under the vise allowing it to be rotated and set at a variety of angles. Large workpieces can be held directly on the table surface through a combination of T-nuts, bolts, and clamps. An index chuck permits the rapid positioning of the work, usually indexing in 15° increments. The rotary table gives the mill its 4th axis with its circular movement. Circles, partial curves, angularly spaced holes, curved slots, and O- ring grooves. This fixture is graduated in degrees and minutes of a degree. Tooling-

End mills are the most common cutter used on the vertical milling machine. They are extremely versatile in that they can be used for surface cuts, slotting, and side (or profiling) cuts. End mills come in many types, each being suited for a particular application. End mills are fluted, much like drills, and the number of flutes determines what the end mill can do. Two fluted end mills are used for machining aluminum, and are favored for plunge cuts. Four fluted end mills are used in machining the harder metals like steel. Generally, it is not a good idea to use a four fluted end mill when machining aluminum or brass however, since the flutes can fill with material, and no longer cut. The other main characteristic of the end mill is the cutting end of the tool its self. Some end mills are bottom cutting, meaning they can be plunged into material much like a drill, while some are not, and are only useful for cutting on the side. Be careful not to plunge an end mill that is not bottom cutting. Other types of end mills includes the ball end mill, which has a radiused end used to produce a fillet, and corner radiusing end mills, used to round the edges of a workpiece.

Other types of cutters include slitting saws for cutting grooves, shell milling cutters for faster milling of surfaces than is possible with an end mill, flycutters (which are single point cutters for facing large workpieces), formed cutters for cutting special shapes like gears; and groove cutters like T-slot and dovetail cutters. Milling cutters are expensive and easily ruined if not taken care of when using or storing. Failure to obtain satisfactory results on a job can many times be attributed to inappropriate selection of the proper milling cutter. Machine Controls-

The speed or RPM of the spindle is set through a variable- speed changing mechanism. This is a dynamic adjustment. Speed changes are done only with the motor running. This is different than the range changes, which are done only with the motor turned off, static. The feed is the rate that the workpiece is fed into the cutter. The shop mills are equipped with a variable power feed. This means that while it is easy to feed at a very slow feed, it is also easy to accidentally feed too fast when using a small cutter, possibly breaking the cutter while in operation. May

factors and conditions influence the speed and feed at which the material is worked. The operator must take into account rigidity of the workpiece and cutter, the depth of cut, and the desired finish. It is generally a good idea to start with a slow feed rate, and increase it until an efficient removal rate is achieved. Feed rates are decreased for finer finishes or greater depths of cut, and maximized for roughing cuts. MACHINING OPERATIONS

Once the preliminary operations and selections have been accomplished, a quick check should be made to be sure that work and fixtures will clear any parts of the machine, and that the cutter will not strike the table or fixtures. All table movements that will not be used on a cut should be locked, and those that will be used should be unlocked. The head controls should be checked for proper range and speed. When starting the motor, make certain the cutter is rotating in the proper direction. Do not stop the cutter in mid cut and make no adjustments with the cutter in contact with the workpiece.

There are two types of milling to be discussed. Conventional milling is where the workpiece is fed opposite the direction of the rotation of the cutter, and climb milling is when the workpiece is fed in the direction of rotation of the cutter. Each has its own advantages and disadvantages. Climb milling draws the part into the cutter, and can violently take up any backlash in the table. However, it does produce a smoother finish. Conventional milling is the more preferred method, and will be used for every cut except the finishing cut. When using an end mill, there are certain general rules that should be followed when making cuts.

1. The greatest depth of cut should never be more than 1/2 the diameter of the end mill.

2. Do not plunge an end mill more then 1-1/2 times its diameter. This is also true for slotting. Do not, in a single pass, cut a slot deeper than 1-1/2 its width.

3. Do not edge mill to a depth of more than 1-1/2 times the diameter of the cutter.

SAFETY

The vertical mill can be a safe machine, but only if the student is aware of the hazards involved. In the machine shop you must always keep your mind on your work in order to avoid accidents. Distractions should be taken care of before machining is begun. Develop safe working habits in the use of safety glasses, set-ups, and tools. The following rules must be observed when working on the milling machines in the Student Shop:

1. No attempt should be made to operate the mill until you understand the proper procedures for its use and have been checked out on it.

2. Dress appropriately. Remove all watches and jewelry. Safety glasses or goggles are a must.

3. Plan out your work thoroughly before starting. 4. Know were the location of the OFF switch is. 5. Be sure the work and holding device are firmly attached to the table. 6. Get help in moving any heavy attachments associated with the mill. 7. Stop the machine before making any adjustments or measurements. 8. Never reach over or near any rotating cutter. 9. Take care to prevent running the cutter into the vice or table.

10. Never leave a machine running unattended.

11. top the machine before removing chips, ( remember that chips can be very sharp).

12. Keep the floor around the machine clear of chips. Wipe up spilled cutting fluids immediately.

13. Use a piece of cloth for protection of the cutter and your hands when handling the milling cutters.

LATHE One of the most important machine tools in the metalworking industry is the

lathe. A lathe operates on the principle of a rotating workpiece and a fixed cutting tool. The cutting tool is feed into the workpiece, which rotates about its own Z-axis, causing the workpiece to be formed to the desired shape.

The lathes in the Student Shop are commonly referred to as “engine lathes”. This is the most popular type of lathe in industry because of its versatility and ease of operation. Some of the more frequently performed operations on the engine lathe are: turning cylindrical surfaces, facing flat surfaces, drilling and boring holes, and cutting internal or external threads. Although relatively simple, these few operations provide a wide range of manufacturing ability.

Lathes are classified according to the maximum diameter, (know as the “swing”), and the maximum length of the workpiece that can be handled by the lathe. Another important characteristic of any lathe is the maximum horsepower that can be supplied to rotate the workpiece. A new way lathes are being classified today is by their controls, manual, computer-numerically-controlled, (commonly called CNC), and the latest referred to as hybrid lathes. Hybrid lathes are a cross between the standard manually operated lathe and the computer operated lathe, CNC. LATHE CONSTRUCTION

There are four main groups of components that comprise the basis for all engine lathes. These consist of the: bed, headstock, tailstock, and the carriage. Please refer to figure for clarity.

The bed is the foundation of the engine lathe. The bed is a heavy, rugged casting made to support the working parts of the lathe. The size and mass of the bed gives the rigidity necessary for accurate engineering tolerances required in manufacturing today. On top of the bed are machined ways that guide and align the carriage and tailstock, as they are move from one end of the lathe to the other. The headstock is clamped atop the bed at the left-hand end of the lathe. The headstock contains the motor that drives the spindle through a series of gears. The workpiece is mounted to the spindle through means of a chuck, faceplate, or collet. Since the headstock contains the motor and drive gears, the speed or RPM at which the spindle rotates is also controlled here. The headstock also contains the power feed adjustments, which are the controls for the rate at which the carriage moves when the power feed lever in engaged.

The carriage assembly moves lengthwise, (longitudinally), along the ways between the headstock and the tailstock. The carriage is composed of the cross slide, compound rest, saddle, and apron. The saddle is an H shaped casting mounted on top of the ways, and supports the cross slide and compound rest. The apron is fastened to the saddle, and houses the automatic feed mechanisms. The cross slide is mounted on top of the saddle, and can be moved either manually or automatically across the longitudinal axis (Z-axis) of the spindle. This provides the lathe’s X-axis, which is the diameter the workpiece is machined to. The compound rest holds the tool post, which supports the cutting tool. Mounted on top of the cross slide, the compound rest can be swiveled to any angle in the horizontal plane. This is useful when cutting angles and short tapers on the workpiece. PROCEDURES

Proficiency in lathe operations involves more than simply “turning” metal. Quality work can be produced on the lathe if the job is planned in advance. There are two main categories of procedures to be followed when machining parts on a lathe: the preliminary operations, and the machining operations.

Preliminary Operations- Cleaning- The first, (and last), procedure in any machining operation. Without clean equipment and tools, the accuracy of the finished product diminishes quickly. The accuracy, durability, and longevity of the equipment and tools depend on being kept clean. In today’s high tolerances in engineering, cleanliness is critical. Holding the workpiece- There are several types of holding devices used on the engine lathe. The most common is the three-jaw chuck (see figure). This chuck permits all three jaws to work simultaneously, automatically centering round or hexagonal shaped pieces. Each jaw only fits with the particular groove in the exact chuck it was made for, so the jaws are not interchangeable between chucks. The advantages of this type of chuck are that it is very versatile, quick set-up, large range of sizes, and uniform holding pressure on the workpiece. The disadvantage is that is the least accurate of the holding devices in the Student Shop. The three-jaw chuck only has an accuracy of between +0.005” to +0.010”, depending upon its condition.

The second type of chuck is the four-jaw chuck, (see figure). This is also called the independent chuck because each of its jaws operates independent of the other three. This permits odd shaped work to be held and centered about a feature. The advantages are that it is versatile, provides a secure hold o the workpiece, large range of sizes, and has extremely accurate centering method. The four-jaw chuck is accurate to +0.0005”. The main disadvantage is the long process necessary to center the workpiece, requiring a high level of in the use of a dial indicator.

A third important holding device is the spring collet. This is a popular style due to its ease of use and good accuracy. The spring collet will usually repeat within +0.001”. Disadvantages to the spring collet are limitations to the size of each collet, (+0.005”), restrictive to only round workpieces, and a maximum diameter of 1-1/16”.

Tooling- Tools must be clamped securely to the tool post regardless of what type of

tool is being used. It is also recommended to have the cutting tool extended the least amount possible to reduce torque and vibrations induced in the tool when cutting. The tools must be adjusted so that their cutting edge is at the height of the

exact center of the workpiece. This Defined as a line running between the center of the headstock and tailstock spindles. Each lathe has a turning, facing and parting tool as part of its tooling accessories. Machine Controls-

Many factors must be considered when determining the correct speed, (RPM), and feed rates. Some of these are: 1. Type of material being machined. 2. Desired finish to the workpiece. 3. Condition of the lathe. 4. Rigidity of the workpiece. Smaller diameters are less rigid. 5. Shape and size of the workpiece. 6. Size and type of tooling being used.

MACHINING OPERATIONS

Once the set-up is complete, a quick check should be made of the machine settings. Next, the work should be checked that it is in the holding device correctly. This is done with the machine OFF, manually rotate the chuck, seeing if there are any interference points or possible inference points. Once this is complete, the machining operations can being. There are usually two phase to machining, roughing and finishing.

The roughing operation is the process of removing the unwanted material to within about 1/32”, (about 0.030”), of the finished dimension. Roughing speeds are approximately 80% of the finishing speeds. Roughing feed rates are from 0.005” to 0.010”/revolution. Sizes and lengths should be check after the roughing operation before going on to the finish operation.

Finish operations are used to bring the workpiece to the required size, length, shape, and surface finish. Depending upon the surface finish desired, feed rates are generally between 0.001” to 0.005”/revolution.

The main difference between roughing and finishing cuts is the depth of cut. Depth of cut refers to the distance the cutter has been fed, or advanced, into the workpiece surface. The depth of cut, like feed rates, varies greatly with the machining conditions. Material, hardness, speed, and total material needed to be removed all play a part in figuring the depth of cut amount. Roughing depth of cuts are greater, or deeper than finishing depth of cuts, which are finer or shallower. All cuts, whether roughing or finishing, should be made from right to left. Traveling towards the chuck as oppose to away from it offers the greatest rigidity and therefore the greatest safety. SAFETY

The lathe can be a safe machine, but only if the student is aware of the hazards involved. In the machine shop you must always keep your mind on your work in order to avoid accidents. Distractions should be taken care of before machining is begun. Develop safe working habits in the use of safety glasses, set-ups, and tools. The following rules must be observed when working on the lathes in the Student Shop:

1. No attempt should be made to operate the lathe until you understand the proper procedures for its use and have been checked out on it.

2. Dress appropriately. Remove all watches and jewelry. Safety glasses or goggles are a must.

3. Plan out your work thoroughly before starting. 4. Know were the location of the OFF switch is. 5. Be sure the work and holding device are firmly attached. 6. Turn the chuck by hand, with the lathe turned OFF, to be sure there is no

danger of striking any part of the lathe.

7. Always remove the chuck key from the chuck immediately after use, and before operating the lathe. Make it a habit to never let go of the chuck key until it is out of the chuck and back in its holder.

8. Keep the machine clear of tools. Tools must not be placed on the ways of the lathe.

9. Stop the lathe before making any measurements, adjustments, or cleaning. 10. Support all work solidly. Do not permit small diameter work to project too far

from the chuck, (over 3X’s the work’s diameter), without support. 11. If the work must be repositioned or removed from the lathe. Move the cutting

tool clear of the work to prevent any accidental injuries. 12. You should always be aware of the direction of travel and speed of the

carriage before you engage the automatic feed. 13. Chips are sharp. Do not attempt to remove them with your hand when they

become “stringy” and build up on the tool post or workpiece. Stop the machine and remove them with plies.

14. Stop the lathe immediately if any odd noise or vibration develops while you are operating it. If you can not locate the source of the trouble, get help from the instructor. Under no circumstance should the lathe be operated until the problem has been corrected.

15. Remove sharp edges and burrs from the work before removing it from the lathe.

16. Use care when cleaning the lathe. Chips sometimes get caught in recesses. Remove them with a brush or short stick. Never use a floor brush to clean the machine. Use only a brush, compressed air, or a rag.

Benchtop Grinder Safety Rules A bench grinder is a machine used to drive an abrasive wheel or wheels. Depending on the grade of the grinding wheel, it may be used for sharpening cutting tools. PROCEDURES 1. Inspect & Adjust Grinder

• Ensure area around grinder is clean and well maintained. Side guard must cover the spindle, nut and flange and 75% of the abrasive wheel diameter*.

• Check the work rest gap – must be no greater than 1/8 inch – adjust if necessary*.

• Note: Replace abrasive wheel if work rest gap cannot be adjusted to less than 1/8 inch.

• Check the tongue guard gap – must be no greater than 1/4 inch – adjust if necessary*.

• Check abrasive wheel for cracks or flaws – replace if necessary*. • If abrasive wheel is worn unevenly, redress using appropriate dressing tool. • Verify the maximum RPM rating of the grinder does not exceed the RPM

rating on each abrasive wheel. • Eye shields must be clean and in position – replace if cracked or broken. • Check work rest and tongue guard gap periodically during use – adjust as

necessary*. • Before a new abrasive wheel is mounted, a visual inspection for cracks or

flaws and a “Ring Test” must be performed. Ring Test: Place your finger through the mounting hole of the new abrasive wheel and lightly tap its face with a hammer or metallic object. A “ring” will sound from a good wheel while a “dull thud” will sound from a wheel with an internal fracture. Do not use cracked, flawed or internally fractured wheels.

2. Don required Personal Protective Equipment (PPE) • Splash-Proof Eyewear or Face Shield and Safety Glasses • Hearing Protection In addition, when applicable don: • Overalls or Apron • Dust Mask • Gloves – Caution: Wear snug fitting gloves to avoid snagging on abrasive

wheel or wire brush 3. Switch “on” Grinder

• Secure loose clothing, • Stand to one side and switch on grinder, • Do not grind soft metals such as lead, solder or aluminum.

4. Grinding • Allow grinder to reach full rpm before grinding, • Position yourself to avoid overbalancing, • Firmly grip object to be ground, • Keep hands and fingers clear of abrasive wheels, • When grinding avoid placing excessive pressure on abrasive wheels, � Grind

object evenly across entire abrasive wheel face, • Do not grind objects on sides of grinding wheels, • Materials may become hot when grinding – use gloves when necessary, • Use an Aluminum Oxide wheel to grind aluminum & other non-ferrous

materials. Use a Silicone Carbide wheel to grind steel & other ferrous materials. Wheels must be “Dressed” when loading (build up of material on wheel face) occurs. “Dressing” is the process of removing bonded material

from cutting grains in the face of the wheel to expose new, sharp cutting edges and provide chip clearance for the material removal process.

5. Switch off Grinder • Switch off grinder when done • Clean area and dispose of grinder particles

SAFETY

1. Abrasive wheel machinery shall not be operated without the appropriate guards in place.

2. Toolrests on bench or pedestal grinders shall be set no more than 1/8 inch from the wheel.

3. Never use a wheel that has been dropped or received a heavy blow, even though there may be no apparent damage. Such wheels may be weakened or unbalanced enough to fly apart on startup.

4. Stand to one side when starting machine. 5. Do not grind on side of wheel unless wheel is specifically designed for such

use. 6. Do not use excessive pressure while grinding. On surface grinder do not

exceed .0005” inch downfeed at any time. 7. Report to the Shop Manager immediately any cracked, broken or otherwise

defective wheels. 8. Have the Shop Manager mount and balance new wheels. 9. Keep the grinding wheel dressed. Dressing a small amount frequently is

better than having to dress a lot later and will allow the wheel to cut faster, cooler and with a better surface finish. Dressing is cleaning and smoothing the surface of the grinding wheel.

10. Hold work securely while grinding, use the toolrest to support the work when off-hand grinding on bench or pedestal grinders.

11. Do not grind aluminum. It will clog the wheel and aluminum dust is explosive. Check with shop staff for safety instructions if aluminum must be ground.

12. Always wear safety glasses when grinding on bench or pedestal grinders. The addition of a face shield is recommended.

13. If a magnetic chuck is being used, on the surface grinder, make sure it is holding the work securely before starting to grind.

Disc and Belt Sander Safety Rules The belt sander is extremely useful for doing many different sanding jobs. It

will produce a smooth surface on a board in less time and with less work than hand sanding.

The belt sander also offers an important advantage over disc sanders: The abrasive belt travels in one direction only, leaving no swirl marks. With a belt sander, you can sand parallel to the grain of the wood. This will produce a smooth finish free of scratches and tiny blemishes.

In addition, the belt sander has capabilities which permit you to sand end, miter, and bevel cuts quickly and accurately, sand convex and concave shapes, "round over" the edges and the ends of workpieces, and create compound curves in wood. You can also use the belt sander to sharpen tools.

The belt sander works by driving a continuous abrasive belt over two drums: a drive drum and an idler drum. The drive drum is covered by a nonslip rubber sleeve and drives the belt continuously in one direction. The idler drum is spring loaded to automatically tension the belt. The tension knob on the left side of this drum releases a torsion spring that presses the drum forward to tension the belt. The tracking knob (behind the tension knob on the left side of the belt sander) changes the angle of the idler drum in relation to the drive drum. This, in turn, centers the abrasive belt on the backup plate. Since the abrasive belt moves in a straight line, the machine is particularly suitable for sanding parallel to the wood grain. In some particular instances, especially when a lot of material must be removed, crossgrain or diagonal sanding techniques may be used.

The belt width doesn't limit how wide stock must be in order to be sanded. Repeat passes and special procedures permit smoothing materials that are wider than the belt itself. SAFETY

1. Danger Zone—The belt sander danger zone is 3" out from the abrasive belt in all directions. When you're working with the worktable parallel to the belt or without the worktable, the danger zone also extends 6' in back of the belt sander; the moving belt can throw stock in this direction. Never stand in line with the rotation of the belt.

2. Wear proper eye and ear protection. 3. Connect a hose from your dust collection system to the dust chute on the belt

sander or wear a dust mask. When doing a lot of sanding, wear a respirator. 4. If you're not using a dust collection system, always keep your hands away

from the dust chute when the machine is running. 5. Be sure the bottom edge of the worktable is not more than 1/16" above the

abrasive belt when you are working. Because of the direction of rotation of the belt, small pieces of stock—or a finger, for that matter—can be drawn down between the abrasive belt and the worktable. The smaller the clearance between the belt and the worktable, the easier it is to prevent accidents. However, never let the edge of the worktable touch the abrasive belt. This will grind away part of the worktable.

6. Never tilt the table toward the belt. The rotation of the belt could wedge your hands between the table and belt.

7. Use the belt sander in either the vertical or horizontal position. Avoid positions in between unless you install the extra bolt.

8. Do not use worn belts. • Let glued-up stock dry at least 24 hours prior to sanding. •

9. Never sand particle board or paint that contains lead.

10. Don't attempt to sand pieces that are too small or too large to be safely controlled. To maneuver small workpieces on the belt sander, grip them in a pair of pliers (Figure 19-5), clamp them in a drill chuck, or make a special fixture to hold them. (Metal jaws should be covered with tape or leather so they don't leave marks on the stock.) This will give you better control and keep your fingers out of the danger zone.

11. Always check the machine before you turn it on. Remove any adjust- ing wrenches or anything that may be resting on the belt.

12. Be certain the abrasive belt is tracking properly and does not rub against any part of the belt sander.

13. • Whenever possible, support the workpiece by backing it up or guid- ing it with the worktable.

14. Check that the worktable is locked securely in place. 15. Always turn the belt sander on first; then put the workpiece in posi- tion.

Never turn the machine on with a workpiece resting on the belt. 16. Never spin the abrasive belt, drive shaft, pulley, or V-belt to start the belt

sander. Keep your hands away from these parts when the machine is plugged in.

17. The belt sander must be unplugged from its power source before performing any adjustments or repair procedures, with the exception of belt tracking and crowning. Do not rely solely on the power switch.

Vertical Bandsaw Safety Rules Band saws use thin, flexible, continuous steel strips with cutting teeth on one

edge. They are used primarily for cutting curves in stock or in food processing plants to cut and trim meat, poultry, and fish. The blade runs on two pulleys, driver and idler, and through a work table where material is manually fed. Automatic feeds can be used for production cutting. However, this machine is usually considered a manual-feed tool. The two types of band saws, horizontal and vertical, are named for their respective cutting blade positions. Blade Terminology

A. Kerf: Amount of material removed by blade during cutting. B. Tooth Set: Amount each tooth is bent left or right from blade. C. Gauge: Thickness of blade. D. Blade Width: Widest point of blade mea- sured from tip of the tooth to back

edge of the blade. E. Tooth Rake: Angle of tooth from a line per- pendicular to length of blade. F. Gullet Depth: Distance from tooth tip to bot- tom of curved area (gullet). G. Tooth Pitch: Distance between tooth tips. H. Blade Back: Distance between bottom of gullet and back edge of blade. I. TPI: Number of teeth per inch measured from gullet to gullet.

PROCEDURES

• Select the proper blade width, refer to a chart which gives the blade width for minimum radii cuts.

• The teeth on the blade of a properly installed bandsaw should point downward in the direction of blade travel.

• Check tension and tracking of the blade frequently, make adjustments as needed.

• Disconnect power and turn wheels by hand to see if the blade is tracking in the middle of the wheel.

• Be sure material being sawed is free of nails, paint and other obstructions. • Plan your cuts carefully. Lay out work clearly, use relief cuts, and avoid

backouts. • Do not cut stock until the machine is running at full speed. • Always place stock flat on the bandsaw • Do not force the stock into the blade at a rate faster than it can be readily

cut. • If sawing freehand, use one hand to guide the stock into the blade and the

other hand to push the stock into the blade. DO NOT PUSH STOCK WITH HANDS IN LINE WITH THE BLADE.

• Do not place excess stress on the blade by twisting the stock, cut curves gradually.

• If a problem develops and the blade has to be backed out, shut off the machine and wait until the blade has stopped.

• If the blade breaks, shut off the power and move away from the machine. Never try to free a blade while the wheels are turning.

• An indication of a cracked blade is a rhythmic click as the cracked portion of the blade passes through the wood.

• Cylindrical stock should be mounted in a holding device to keep it from spinning and crowding the blade while being cut.

• Make sure the band saw has stopped before leaving it. SAFETY

1. The upper guide and guard should be set as close to the work as possible, at least within 1/2 inch.

2. If the band breaks, immediately shut off the power and stand clear until the machine has stopped.

3. Examine blade before installing to see if it is cracked, do not install a cracked blade.

4. Use the proper pitch blade for the thickness of the material to be cut. There should be at least 3-4 teeth in the material when cutting.

5. Do not run the band saw at a higher speed than recommended for the material being cut.

6. If the saw stalls in a cut, turn the power off and reverse the blade by hand to free it.

7. Band saw rpm is to be adjusted while the band saw is running. Band saw speed range is adjusted when the machine is stopped.

Horizontal Bandsaw Safety Rules Band saws use thin, flexible, continuous steel strips with cutting teeth on one

edge. They are used primarily for cutting curves in stock or in food processing plants to cut and trim meat, poultry, and fish. The blade runs on two pulleys, driver and idler, and through a work table where material is manually fed. Automatic feeds can be used for production cutting. However, this machine is usually considered a manual-feed tool. The two types of band saws, horizontal and vertical, are named for their respective cutting blade positions. Blade Terminology

J. Kerf: Amount of material removed by blade during cutting. K. Tooth Set: Amount each tooth is bent left or right from blade. L. Gauge: Thickness of blade. M. Blade Width: Widest point of blade mea- sured from tip of the tooth to back

edge of the blade. N. Tooth Rake: Angle of tooth from a line per- pendicular to length of blade. O. Gullet Depth: Distance from tooth tip to bot- tom of curved area (gullet). P. Tooth Pitch: Distance between tooth tips. Q. Blade Back: Distance between bottom of gullet and back edge of blade. R. TPI: Number of teeth per inch measured from gullet to gullet.

PROCEDURES

1. Examines workpiece to make sure it is suit- able for cutting. 2. Adjusts blade tilt, if necessary, to correct angle of desired cut. 3. Adjusts fence to desired width of cut, then locks it in place.

4. Checks outfeed side of machine for proper support and to make sure workpiece can safely pass all the way through blade without interference.

5. Securely clamp workpiece into horizontal bandsaw vise. 6. Puts on personal protective equipment, and locates push sticks if needed. 7. Starts saw. 8. Feeds workpiece all the way through blade while maintaining firm pressure on workpiece

against table and fence, and keeping hands and fingers out of blade path and away from blade.

9. Stops machine. TIPS FOR HORIZONTAL CUTTING • Use work stop to quickly and accurately cut multiple pieces of stock to same length. • Clamp material firmly in vise jaws to ensure a straight cut through the material. • Let blade reach full speed before engaging workpiece • Never start a cut with blade in contact with workpiece. • Wait until blade has completely stopped before removing workpiece from vise, and

avoid touching cut end—it could be very hot! • Support long workpieces so they won't fall when cut, and flag ends of workpieces to

alert passers-by of potential danger • Positions blade guides approximately ¼” from workpieces to minimize side-to-side

blade movement. • Use coolant when possible to increase blade life.