Circular Saw

The material for this handout has been adapted from Chapter 54 (pages 350-364) of Wood: Technologyand Process, by John L. Feirer, Mission Hills, California: Glencoe/Macmillan, 1987.

After studying this handout, you will be able to:• Identify the main parts of the circular saw.• List those precautions that must be followed in operating the circular saw.• Describe how to rip with the circular saw.• Describe how to perform a crosscutting operation on the circular saw.• Describe how to cut a miter with a circular saw.• Describe how to cut a groove on the circular saw.• Describe how to cut a rabbet with a circular saw.• Describe the use of a dado head with the circular saw.

LOOK FOR THESE TERMS

antikickback pawls guard saw-raising handwheelarbor miter gauge saw-tilt handwheelcarbide tip push stick splittercircular saw ripping fence table sawdado head

The circular saw, or table saw, is a machinefor cutting wood. Ripping and crosscutting arethe chief cutting operations. The machine partsare shown in Fig. C-1. In addition, all circularsaws should have a guard, a splitter, andantikickback pawls (fingers) to protect theoperator from injury. Fig. C-1. Saw size isindicated by the largest diameter of saw bladethat can be used on the machine. The mostcommon sizes are 8, 10 & 12 inch tilt arborsaws. The saw-raising handwheel is usuallyunder the front of the table. It is used to raiseand lower the saw blade. The saw-tilt

handwheel, usually on the left side, is used to tiltthe arbor for cutting at an angle.

SELECTING A SAW BLADE

There are many kinds of circular saw blades.The most common are ripsaw (riptooth),crosscut, and combination. Fig. C-2. Whenmany different operations are done one afteranother, it is a good idea to use a combinationblade. Fig. C-3. Many saw blades have carbidetips. Carbide is extremely hard. It keeps theblade sharper for a longer period of time.

C-1 Circular Saw

SAFETY

• Raise the saw blade from l/8 to 1/4 inch (3 –6 mm) higher than the thickness of the stockto be cut.

• When changing saw blades or using a dadohead, make sure the main switch is off.When possible, pull the plug from thereceptacle to prevent accidental starting.

• Hold the stock to be sawed against the fenceor miter gauge. Never try to saw "freehand"(without holding the stock against the fenceor miter gauge). Use a ripping fence forripping operations. Use a miter gauge for allcrosscutting operations.

• Keep the saw guard down over the saw bladewhile operating the saw.

• Make all adjustments when the saw is at adead stop. These adjustments include heightof the saw blade, angle setting, fenceadjustments, and all special setups. Alwaysstop the saw before changing anyadjustments.

• When setting up the saw for any sawingoperation, check to see that the saw bladerevolves freely in the correct direction.Check that it is securely fastened to thearbor. Check that any clamps or knobs onthe fences are properly tightened.

• Make sure that the antikickback pawls(fingers) behind the saw blade are always inplace. These resist the tendency of the sawto throw the stock upward and toward theoperator.

• Use the splitter guard and antikickbackpawls or fingers when ripping. Wood cutwith the grain tends to spring the kerf closedand bind the blade. Fig. C-4. The splitterprevents this from happening. If the splitteris not used, stop the machine and insert awedge in the kerf just as soon as the cut haspassed the back of the blade. Fig. C-5.

• Always use the saw guard. The saw guardcovers the blade and the area around it, whileallowing the stock to slide under it. Neveroperate the saw without the guard in place

C-6 When ripping long stock, have someone helpyou.

• unless a special jig or fixture is used as aguard.

• Use a push stick to push the stock past theblade if the space between the saw blade andthe fence is 6 inches (150 mm) or less.

• Stand to one side of the saw blade. No oneshould ever stand in line with the blade wherekickback could cause serious injury.

• Stock to be ripped must have a straight, trueedge and must lie flat on the table. Never cutstock on the saw if it is warped, "in wind," orhas a rough or bowed edge.

• Whenever helping to "tail-off," hold theboard up and allow the operator to push thestock through the saw. Never pull on aboard being ripped. Fig. C-6.

• Fasten a clearance block to the ripping fencewhen cutting off short lengths of stock.Make sure the block is clamped ahead of theblade. Use a sliding miter gauge to hold thestock. Never use the ripping fence as a stopwhen crosscutting. It will cause kickback.

• Do not force stock into a saw blade fasterthan it will cut.

• Never reach over the saw blade! Have ahelper take the stock away.

• Do not allow your fingers to come closerthan 5 inches (125 mm) to the saw bladewhen cutting stock.

• Use a stick or board to clear away scrapsclose to the saw blade. Do not use yourhand.

• Have your instructor check all special setupsand blade changes before the saw is started.

• Remove all special setups and the dado headfrom the saw after use.

• Do not try to cut cylindrical (round) stock onthe saw.

CHANGING A BLADE

Snap out the throat plate around the saw.Obtain a wrench that will fit the arbor nut. On

most circular saws, the arbor has a left-handthread and must be turned clockwise to loosen.Fig. C-7. However, some manufacturers use aright-hand thread on the arbor. If so, you mustturn the arbor nut counterclockwise to remove it.Always check the thread before loosening. If thenut does not come off easily, force a piece ofscrap wood against the blade to keep the arborfrom turning. Remove the nut, the collar, and theblade. Now mark the arbor with a slight file cutor prick-punch mark. Always turn the arbor sothe mark is "up" before putting on a new blade.Place the trademark on the blade at the top, inline with the mark on the arbor. Replace thecollar and nut.

RIPPING

Before you rip stock to width on the circularsaw, make sure that one edge of the stock is true.If it is not, plane one edge. Then, with the poweroff, adjust the saw blade to a height of l/8 to 1/4inch (3 – 6 mm) more than the thickness of thestock. Figs. C-8 and C-9.

Adjust the ripping fence to the correct width.Do this by holding a rule or try square againstthe fence and measuring the distance to the sawblade. On many machines, the width for rippingis found directly on a scale mounted on the frontedge of the saw table. Lock the ripping fence soit is tight. Make sure the guard, splitter, andantikickback pawls or fingers are in place.

Turn on the power. Place the stock on thetable. Stand to one side, not directly in back ofthe saw blade. To start the cut, apply forwardpressure with one hand as you hold the stockagainst the fence with the other. Do not applytoo much forward pressure on a small saw. Thiswill make the saw burn or stop altogether.Continue to feed the work into the saw with evenpressure. Figs. C-10, C-11, and C-12.C-7 Removing a blade. With the plug pulled, hold a piece of

wood against the blade to keep it from turning. Then turn thenut with a wrench of the proper size. On most saws the arborhas a left-hand thread and must be turned clockwise to loosen it.However, some arbors have a right-hand thread. If so, you mustturn it counter-clockwise to remove it.

C-10 The fence for ripping can be placed on either the right or left side

If the stock is hardwood and quite thick, youmay need to begin with the saw set at less thanthe total thickness. You may need to run itthrough several times rather than trying to cutthrough the thickness in one operation.

When cutting to narrow widths, hold the pushstick in your right hand. As the rear edge of thestock clears the table, apply forward pressurewith the push stick until the cut is completed.Figs. C-13, C-14, and C-15.

CROSSCUTTING

The miter gauge fits into either groove of thetable but is most often used in the left groove.Some operators attach a squared piece of stock

C-11 Ripping stock. Push with your right hand and hold the stockagainst the fence with your left. If the stock is narrow, have a pushstick handy for finishing the cut. Keep your hands away from theblade.

C-12 Use of the operators hand for ripping. When the spacebetween the saw blade and the fence is greater than 6 inches(150 mm), the operator can safely push the stock with her/hishand. The two fingers locked over the fence helps to keep theother fingers away from the saw blade.

C-14 Custom designed push sticks. Operators can useproblem solving techniques to design push sticks for

specific operations on the circular saw.

C-15 Cutting thin pieces. This push block, which slidesalong the fence, makes it easy to cut thin pieces safely. Extracare must be taken when cutting thin pieces because it isdifficult to perform this operation when a guard is in place.

the same width as the miter gauge to its face tobetter support the work. To make a square cut,set the gauge at a 90 degree angle. Check byholding a try square against the gauge and thesaw blade. Mark the location of the cut clearlyon the front edge or face of the stock. Fig. C-16and C-17.

Set the blade to the correct height. Hold thestock firmly against the gauge and slide both thework and gauge along the table to complete thecut. Fig. C-18 and C-19. If you must cutseveral pieces to the same length, use one of thefollowing methods:

• Set the stop rod that is attached to the mitergauge to the correct length. Fig. C-20.

• Clamp a small block of wood to the rippingfence just in front of the saw blade. Thefence with block attached acts as a lengthguide. The attached block must be provideenough space between the blade and thefence to allow a cut-off piece of material toturn diagonally without touching the bladeor the fence. Fig. C-21. Never use theripping fence only as a length guide. If youdo, the piece will lodge between therevolving saw and the ripping fence. Itmay kick back with terrific force.

C-16 Accurate cross cutting. With the guard lifted and theblade stopped, align the squared line on the edge of the stockto cutting edge of the saw tooth so that the saw blade will cuton the waste side of the line. Gripping the stock and mitergauge tightly; pull the stock back from the blade, set the guardin place, start the saw and make the cut.

C-17 A second method for cross cutting. A line on thetable directly behind the saw blade will make it easy toline up the cut. Note, changing the saw blade mayrequire the operator to establish a new line.

C-18 Crosscutting. The miter gauge is set at a rightangle to the blade. An even forward pressure should beapplied to the stock.

C-19 Safely finishing a cross cut. As soon as the sawblade cuts through the stock, gently slide the stock beingheld against the miter gauge slightly away from the sawblade, pull the stock and the miter gauge back. Turn thepower off and allow the saw blade to stop completelybefore attempting to remove the cut off piece.

• Fasten a wood extension to the miter gauge.Then clamp a stop block to it to control thelength of cut. Fig. C-22.

CUTTING SHEET STOCK

Sheet stock, such as plywood, particle board,and hardboard, comes in large sizes (usually 4 x8 feet). These are hard to handle. It is often agood idea to cut the large sheets into smallersizes with a hand saw or portable power saw.However, some circular saws have extensiontables that make it possible for one person tohandle large sheets safely. Use a fine-toothedcrosscut saw to cut plywood. Use a carbide-tipped saw to cut the other materials. Placeplywood on the table with the good side up.

MITERING

To make a miter cut, adjust the miter gauge tothe correct angle and proceed as in crosscutting.Hold the stock firmly against the miter gaugebecause it tends to creep toward the revolvingsaw as the cut is made. Figs. C-23 and C-24.To make a compound miter cut, set the gauge tothe correct angle and tilt the blade.

BEVELING AND CHAMFERING

To cut a bevel or chamfer when you are eitherripping or crosscutting, you must tilt the sawblade to the correct angle for the cut. The

gauge, which shows the angle of tilt of thesawblade, is on the front of the saw just belowthe table. After making the adjustment, checkthe angle by holding a sliding T-bevel againstthe tabletop and saw blade. After you have thecorrect angle, you can proceed as for ripping orcrosscutting. Fig. C-25.

GROOVING

Cutting a groove on the circular saw willsimplify the making of a spline joint. Fig. C-26. Lay out the groove on the edge of the stock.Set the circular saw to a height equal to thedepth of the groove. Adjust the ripping fence toallow the cut to be made just inside the layoutline. Hold one surface of the stock firmlyagainst the fence and make a cut. Reverse thestock and make a second cut. If necessary, youcan make several cuts in the waste stock of thegroove. Clean out the groove with a sharpchisel. A groove can also be cut with a dadohead.

RABBETING

A rabbet can easily be cut on the end or edge ofstock with a circular saw. Lay out the rabbetjoint. Set the saw blade to a height equal to thedepth of the rabbet. If the rabbet is to be cut atthe end of the board, hold the stock against amiter gauge and make the shoulder cut. Fig. C-27. Then set the saw blade to a height equal tothe width of the rabbet. Set the ripping fence to aposition that will permit the saw kerf to be justinside the layout line. Hold the stock on end withthe surface opposite the rabbet firmly against theripping fence. Make the second cut.

An edge rabbet is cut in the same way, exceptthat the ripping fence is used for making bothcuts.

TENONING

Making mortise-and-tenon joints is quite simplewhen the tenon is cut on the circular saw. Layout the tenon. Set the saw blade to a height equalto the thickness of stock to be removed from oneside of the tenon. Hold the stock against themiter gauge and make the shoulder cuts. Afterthis is done, set the saw blade to a height equal tothe length of the tenon. Now select a homemadeor commercial tenoning jig. Figs. C-28, C-29,and C-30. The simplest method of cutting thecheek is to clamp the stock to the tenoning jig andposition the jig and fence so as to cut out thecheek on the side away from the jig. Fig. C-31.

Then turn the stock around and cut the othercheek without changing the location of the fence.

USING A DADO HEAD

A dado head will cut grooves or dadoes from1/8 to 2 (3 – 50 mm) inches in width. Figs. C-32and C-33.

This head is equally adapted to cutting with oracross the grain. One dado blade will cut agroove 1/8 inch thick. Two will make a cut 1/4

inch thick. Cutters of different widths can be putbetween these two dado cutters to cut a groove ofany width. This attachment is especially usefulfor cutting grooves, tenons, dadoes, and lapjoints. Figs. C-34 and C-35.

USING AN ADJUSTABLE DADO HEAD

An adjustable dado head gives a good, cleancut and is easy to use. Figs. C-36 and C-37.Set the width by loosening the arbor nut androtating the center section of the head untilthe width mark on this part is opposite thecorrect dimension. This adjustable dadohead will make cuts from 1/4 to 13/16 inch (6– 21 mm) wide and up to 3/4 inch (19 mm)deep. It can be used for making all kinds ofcuts.

CUTTING A TAPER

The best way to cut a taper is to use anadjustable taper jig. Fig. C-38. Mark a line toindicate the taper to be cut. Then adjust the jiguntil the line of the taper cut is parallel to thefence. Fig. C-39.