Sliding Compound Miter Saw

Safety

Description of the Saw and its parts/controls:

The Saw is displayed as purchased (with no dressing). The students can observe the fact that the Saw in its raw state, has a backstop with adjustable openings and a slot in which the blade can be dropped into. (These openings are rather large, but function just fine for cutting up framing lumber. This type of Saw is commonly used on construction sites to cut framing lumber, and the parts are generally large enough to bridge across both back rails without getting grabbed and thrown through the gap between the back rails. There is often some “tear-out” at the back edge of the lumber, but that doesn’t matter much when you’re framing a house. At the Miter Saw, the operator places the work piece on the Saws platform, and moves the blade through it while the material is securely braced against the backstop. This Saw is only to be used for cross cutting, not ripping, since there is no safe way to support a rip-cut.

This machines’ official name is “Sliding Compound Miter Saw”, but over the years on construction sites, it earned the nickname, “Chop Saw”, for the sake of brevity. This is a finely tuned instrument, and can be used to make very accurate cuts, even with small pieces of material. Of course large pieces can be cut accurately also. It can slide out to make crosscuts up to 12 inches across by unlocking the slide mechanism, which in this case is an articulated arm. This is called an “Axial-Glide system.”

You can unlock the axial glide by pressing down on the release lever on the left side of the Saw. Pivoting the Saw left or right, and tilting the Saw left or right can make compound miter cuts. A Compound miter is a combination of both a miter and a bevel. Pivoting sets up the miter angle and tilting sets the bevel angle. Using these two features together can create some complex joinery, but more often, only one or the other is used.

Miter Pivoting Mechanism

To pivot the Saw left or right for miter cuts, you must first loosen this miter arm locking knob located at the front of the machines’ miter arm, by turning it counterclockwise a couple of times. There’s a spring-loaded lever underneath the locking knob, which must be lifted up. This releases the detent pin from the detent rack under the Saw table. Lifting and holding up on the Detent Release Lever allows the Saw to be pivoted left and right. There’s a row of slots, or “detents” on the detent rack under the side table that allow the operator to quickly lock the miter position to standard settings such as zero, 22 1/2°, and 45°. The angle gauge is visible on top front edge of the table. There are several other detents along the rack that are commonly used in framing construction, such as roof pitch and gable angles, and all of these detents provide a way to quickly and accurately set the most commonly used standard miter angles. The maximum miter settings are 60 degrees right and 52 degrees left.

You must always lock the miter arm, regardless of the miter setting. Extreme force is not necessary.

Bevel Tilting Mechanism

The bevel tilting mechanism controls are similar to the miter controls in that there is a locking lever, a spring-loaded detent pin, and an angle gauge to allow the operator to see a precise angle to set the bevel.

(Optional Demonstration…) The entire head of the Saw can be tilted for making bevel cuts, by first releasing the bevel lock handle. Lift the red handle on the left side of the Saw table miter arm to unlock. Pull outward on the detent pin and rotate it clockwise to disengage it. Now you can manually tilt the Saw head to the left and lock it at your desired bevel angle. To tilt it to the right, you will first need to move the right hand back rail to the right so that it will be out of the way. You will then need to override the 0 degree positive stop, by turning the red knob on the front right side of the miter arm clockwise. Now the Saw can be tilted to the right and locked at a desired angle. At this point, the right hand back rail can be adjusted to clear the Saw, and locked in position.

Dressing

Now imagine that you need to cut some small parts for a model, and that you need precise clean cuts. That would be nearly impossible to accomplish with these large openings, because the small parts would just be thrown out the back by the Saw blade, and they wouldn’t be cleanly cut since there is no support for them. They could also drop into the Saw table slot along the miter arm. So it becomes relevant to add some “dressing” to the Table and back rails to give support for small parts. Typically, the dressing material we use, is ½” thick MDF (Medium Density Fiberboard), cut at 12” widths for the platform of the Saw, and 4” widths for the back rails. The lengths of these dressing pieces may vary, providing that they are long enough to adequately support the work piece being cut. They can also be made of any other wood-based material of equal thickness. MDF works best because it tends to be flat, ridged, and smooth.

Since most of the parts we make with this Saw are small, you will often find that it is already dressed, and that the platform already has several cuts in it. That is OK, as we try to make the dressing last through multiple uses.  At this point, you will need to go ahead and set your Miter angle because the dressing will soon be covering the angle chart. You will also need to set the depth stop so that you don’t cut all the way through the platform dressing. This preserves the platform for several uses. The depth stop is an adjustable threaded rod located at the top right side of the motor. It lands on a metal plate, which can be disengaged by swiveling it to the left. This reveals a hole that the rod can drop down into for “full depth” cuts. Set the depth to leave about ¼” of the platform intact. Now you will need to dress the back rails.

The Power Switch is located in the control handle of the Saw, and is a squeeze type trigger. It has a safety lock system to prevent accidental activation. To unlock the Power Switch, you must unlock it by sliding the red button on the handle towards the center. So, for a right-handed operation, use your thumb to slide the left button to the right, and then squeeze the trigger. For a left-handed operation, use your thumb to slide the right button to the left, and then squeeze the trigger. You don’t need to keep pressure on the buttons, once you’ve unlocked the trigger. Turn on the dust collector with the red paddle switch located on its’ motor housing, and then make a fresh cut in the dressing.

The dressing will support work pieces all the way up to the blade, and you also have a very clear indication of the Saw kerf. This allows you to accurately set up precisely measured cuts. Lets pretend that you need to make several pieces that are 1” long. You can make a mark at 1” from the end of a part and set up a stop block that distance from the saw kerf. Notice that the corners of the stop block have been sanded back slightly. This is to allow sawdust a place to escape so that the measurement is not impeded by it. Cut-offs, if trapped between the blade and the stop, need to be stabilized so that the blade won’t lift and destroy them. You need to stabilize this 1” cut off with a hold down stick. Now lets pretend that you need 30 pieces this size. You can certainly continue to use the stop block setting in the same way, or you could tape multiple parts together to save time. You need to use paper tape such as masking or painters tape, not cloth tape, and if you take a few minutes to prepare bundles, you will ultimately save more time. Make a left-handed cut to clean up the end of the bundle. Now you can proceed to cut 1-inch sections, using a right-hand cutting technique.

Saw Operation

When making the cut allow the saw to reach full speed rotation above the intended cut material. Bring the saw down through the material at a constant rate, if the saw resists or sounds like it is straining, slow down the drop rate. Once the saw has completely cut the material and in in the saw bed take your hand off the power trigger and allow the saw to stop while in the saw bed. Once the saw has come to a complete stop raise the blade up. This technique will help keep small pieces from being thrown off the saw and reduce the amount of shredding to the cut material.

Hand Hold Down

When operating the saw you will typically use your right hand to turn the saw on, off, and control the cut drop speed. Your left hand will hold the material down on the saw bed and back against the saw fence. Always keep your left hand 6 inches away from the saw cutting area at all times. While making the cut keep constant pressure down and back until the saw has gone all the way through the material and has stopped rotating.  Always place the material to be cut against the back rail (fence) for support. Do not try to cut unsupported work pieces, as the blade will forcefully throw them back into the support fence, which could cause injury and potentially damage the saw. Also, DO NOT ATTEMPT TO CUT ODD-SHAPED WORK PIECES, such as Circular or multi-faceted parts which have no support directly behind the blade path.

Hold down Stick

When making any cuts that require you to hold your materials closer than 6 inches you must use the supplied hold down stick. Note the length of the hold down stick; your hand should always be at the end of the stick allowing for 6 inches of distance from the cutting area while allowing you to hold your material down on the table and back against the fence. Always use a hold down stick over 6 inches long to support parts being cut that are shorter than 6 inches.