- - AGRICULTURE CORE CURRICULUM - - (CLF2000) Advanced Core Cluster: AGRICULTURAL MECHANICS (CLF2400) Unit Title: WOODWORKING _____________________________________________________________________________ (CLF2404) Topic: WOODWORKING POWER TOOLS Time Year(s) 3 hours 1 / 2 / 3 / 4 _____________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the students will be able to: Learning Outcome #: (I-6) - Operate power tools correctly and safely, replacing blades and making adjustments as necessary. Special Material and Equipment: Portable circular saw, stationary circular saw, radial arm saw References: Cooper, Elmer L. (1987). AGRICULTURAL MECHANICS: FUNDAMENTALS AND APPLICATIONS. Albany, NY: Delmar Publishers. Jones, M. M. (1955). SHOPWORK ON THE FARM. New York: McGraw-Hill. Wagner, W. H. (1987). MODERN CARPENTRY. South Holland, IL: Goodheart Willcox. Evaluation: Quiz by instructor. TOPIC PRESENTATION: Woodworking Power Tools SAFETY IN POWER WOODWORKING* Safety Practices for Using Stationary Power Tools The following are general safety practices for using all stationary power tools. 1. Obtain the instructor's permission. Obtain instructor's permission before you use any stationary power tool. 2. Wear proper clothing. Do not wear loose-fitting clothing or jewelry that can get caught in moving parts. Do not wear gloves. Do not roll up long sleeves. 3. Protect your scalp and hair. Pull back long hair in a band or a cap to keep it from getting caught in moving machine parts. 4. Keep guards in place. Guards cannot protect you if they are not in place and in proper working order. 5. Avoid shock. Be sure that equipment is properly grounded. Do not use power tools in a damp or wet place without standing on a rubber mat. 6. Keep the work area clean. Keep the floor free of sawdust, grease, oil, and scraps. Cluttered work areas and benches invite accidents. 7. Unplug the machine. The electrical service to each machine must be disconnected when it is not in use, while it is being serviced, and when the accessories are being changed. 8. Work only at operating speed. Do not use a power tool before it has reached operating speed or while it is coasting to a stop. TABLE SAWS Safety Practices for Using Table Saws Before studying the specific safety practices for using table saws, review the general safety practices for using stationary power tools. 1. Do not roll up long sleeves. Do not wear loosefitting clothing such as coats and ties. 2. When operating the table saw, do not wear gloves. Gloves are bulky and may easily be caught on parts of the table saw, thus creating an additional safety hazard. 3. Remove rings, bracelets, and other loose-fitting jewelry which have the potential of getting caught on the saw or materials. 4. Check the saw blade periodically for broken teeth and cracks. 5. When operating the table saw, stand to one side of the saw blade. 6. Make certain the blade guard, splitter, and anti-kickback device are used for all possible sawing operations. 7. Never reach over the saw blade to remove or hold down a piece of stock. 8. Avoid awkward work positions that may result in slips and contact with the saw blade. 9. Never raise the saw blade more than 1/4" above the material being cut. Lower the blade below the table top before you leave the work area. 10. Do not attempt to rip round or irregularly shaped stock on the table saw. _____________________ * Reprinted by permission of Interstate Publishers, Inc., from MODERN AGRICULTURAL MECHANICS, 2nd ed., by Stanley R. Burke and T. J. Wakeman. Copyright 1992 by Interstate Publishers, Inc. A. Portable Circular Saw 1. Purpose and Parts Identification: a. The portable circular saw is an electric handsaw with a round blade used for making freehand cross, rip, miter, and bevel cuts in lumber and in assembled woodwork. b. Its parts and their purposes are as follows: 1) The handle allows the operator to hold onto the saw. 2) The safety switch controls the power to the saw's motor. 3) The motor converts electrical power into rotary motion. 4) The power cord supplies electrical power to the motor. 5) The shoe or base rests on the wood being cut. 6) The upper guard protects the operator's body from the top of the saw blade. 7) The telescoping guard protects the operator's fingers from the bottom of the blade. 8) The depth adjustment controls blade depth below the shoe. 9) The tilt adjustment tilts the shoe to control blade angle. 10) The arbor shaft supports and rotates the blade. 11) The circular blade cuts the wood. a) Rough cut combination b) Crosscut c) Rip d) Standard combination or miter 2. Safe Adjustment and Operation Procedures for Portable Circular Saw a. Always plug the saw's cord into a grounded outlet, and keep the cord clear of the blade. b. Adjust the depth of the blade so that it extends about 1/8 inch (approximately the depth of one tooth)beyond the thickness of the wood being cut. c. Check both the depth and angle adjustments to insure that they are tight. d. Before turning on the switch, rest the saw base firmly on the wood with the blade clear to turn freely. e. While cutting the wood, stand to one side of the cutting line, and keep the free hand away from the cutting direction and from underneath the wood. f. If the portable circular saw has two handles, keep both hands on them while cutting the wood. g. Always make sure the wood is well-supported so that the kerf does not close and bind the blade while cutting. h. Provide support for thin wood near the cutting line, and secure small pieces to a benchtop or sawhorse with clamps. i. Be alert while cutting in order to avoid cutting into sawhorses or other supports. j. Never use a blade that is dull or out of condition. k. Always stop and unplug the saw before changing blades or making adjustments. A. Table Saw (Stationary Circular Saw) 1. Purpose and Parts Identification: a. The table saw is a stationary circular saw (round blade) mounted in a table, which is used primarily for rip cutting wood. It can also do ripping, beveling, mitering, dadoing, etc. b. Its parts and their purposes are as follows: 1) The body houses the table saw parts. 2) The safety switch controls the electrical power to the motor. 3) The table provides the work area. 4) The circular blade cuts the wood. 5) The blade guard protects fingers from the blade. 6) The saw height wheel is the front wheel that adjusts the height of the blade above the table. 7) The arbor tilt wheel is the side wheel that adjusts the blade tilt angle. 8) The ripping fence guides the wood when making rip cuts. 9) The miter gauge guides the wood when making crosscuts. 2. Safe Adjustment and Operation Procedures for Table Saw a. Always obtain permission from the instructor before operating the saw. b. Use only saw blades that are sharp and properly set. c. During setup, make sure the blade is tightly fastened to the arbor with its teeth pointing towards the operator and able to spin freely. d. Make sure the saw guard, splitter guard, and kickback teeth are in place and use them whenever possible. e. Adjust the blade so that it extends 1/8 to 1/4 inch (approximately the length of one tooth) above the wood to be cut. f. Always hold the wood against the ripping fence or miter gauge when cutting, never freehanded. g. Before using the ripping fence, make sure that it is locked into position at the proper distance from the blade. h. Never use the ripping fence as a guide for crosscutting, or kickback may occur. i. Before using the miter gauge, make sure it slides freely down the entire length of the slot. j. When using the miter gauge, hold the wood firmly against it and down on the table. k. Stand to one side of the spinning saw blade to avoid kickback, and never reach over it. l. Tail off when cutting long or bulky material, but do not push or pull the wood through. m. Always keep a 4-inch margin between fingers and the blade, and use a push stick when ripping narrow pieces. n. Always push the wood clear of the blade before releasing it. o. Never try to cut warped or rough lumber on the saw. p. Stop and disconnect the saw before making adjustments. q. When the cut is complete, turn off the switch and remain by the saw until the blade has stopped. B. Radial Arm Saw 1. Purpose and Parts Identification a. The radial arm saw is a motor and circular blade supported by an overhead arm that is primarily used for crosscutting long lumber on a stationary table. It differs from the table saw in that the wood is usually held stationary while the blade is moved. Like the table saw, it can also be used for mitering, beveling, dadoing, and ripping but it is not as accurate as the table saw. b. Its parts and their purposes are as follows: 1) The overarm supports the motor and blade over the table and allows them to cut miters and move back and forth. 2) The safety switch controls the electrical power to the motor. 3) The miter scale indicates the miter angle of the overarm. 4) The elevating crank raises and lowers the blade. 5) The column supports the overarm and saw. 6) The yoke supports the motor and blade over the table and allows them to turn parallel to the fence to rip wood. 7) The handle pulls the blade into the wood to make the cut. 8) The upper guard protects the operator's body from the spinning blade. 9) The lower guard protects fingers from the blade. 10) The antikickback fingers prevent the blade from kicking back pieces of wood. 11) The fence holds the wood in place for cutting. 12) The table provides the work area. 2. Safe Adjustment and Operation Procedures for a Radial Arm Saw a. Obtain permission from your instructor before using the radial arm saw. b. Use only saw blades that are sharp and properly set. c. During setup, make sure the blade is tightly fastened to the shaft with its bottom teeth pointing away from the operator and able to spin freely. d. Make sure the guards and kickback fingers are in place and use them whenever possible. e. Adjust the blade so it penetrates 1/16 inch below the surface of the table. f. Make sure the adjustment knobs and levers are tight and the carriage lock released. g. Hold the wood to be cut firmly on the table and against the fence, making sure the ends of long boards are supported even with the table. h. Keep a 6-inch margin of safety between your hand and the blade, and keep your arms parallel to the line of cut while holding the wood. i. Before starting the motor, make sure the blade is clear of the wood, and before cutting allow it to accelerate to full speed. j. Never force the saw or cut too fast, because this may bind the blade. k. Since the direction of the teeth pull the blade into the cut, it may be necessary to apply back pressure against the handle to control the speed of the cut. l. When crosscutting, always pull the blade towards you and return the saw to the rear of the table after completing the cut. m. When ripping, always feed the wood into the blade from the side where the bottom teeth are pointing towards you. n. Stop and disconnect the saw before making adjustments. o. After finishing a cut, do not leave the saw until the blade has completely stopped. _________________________________________________________ ACTIVITY: 1. Take a safety test for each power tool. 2. Change blades and adjust the power tools. 3. Operate the power tools correctly and safely to cut lumber and wood panels for an ongoing wood project, such as a toolbox or sawhorse. _________________________________________________________ 6/20/91 OLR/tf #%&C