Setting Up a Radial Arm Saw

Several people have asked for various kinds of help with their radial arm saws. Many of these requests would be solved with a manual, but that has often been lost by a previous owner. This Instructable will take the reader through the steps involved in setting up a radial arm saw. Tools needed are: a couple of Allen wrenches, a couple of good squares, a screwdriver or two, a 7/16 inch, a 1/2 inch and a 9/16 inch wrench and a block. A hammer is also handy, but not absolutely necessary.

Power saws go out of alignment through the vibration that accompanies use. Also, radial arm saws do not like to be moved, and settings will probably drift when one is moved. But, a lot depends on how much precision the user is looking to have from his saw. If you plan to use the saw only to cut 2 x 4s to length, the accuracy you need is not the same as if you were doing fine cabinetmaking with the saw.

Step 1: Assemble the Stand

This is my homemade stand constructed of 2 x 4 pieces and plywood cleats. I made it to take down easily, so the brace pieces attach with corner brackets and wood screws. I made two tool trays that rest on cleats inside the frame assemblies of the stand. You want a stand that makes the table on your saw a comfortable height for working. Commercially made stands are also available. 

I like to have my saw away from the wall. For one thing, this allows me to hang blades and other fixtures on the back of the saw stand. It also allows me to walk around to the back of the saw rather than reach over the table for some set up and service procedures. And, I want to be able to put pieces of lumber eight feet long onto the table and take them off of the table from both sides of the saw. Workshop space is somewhat limited. Moving the saw out from the wall allows me to pass lumber in front of my workbench when things like my vise would otherwise obstruct.

Step 2: Set the Saw Base on the Stand

The saw base rests on the stand and adds stability to it by forming the side of a triangle. The base bolts to the stand. (See the second photo.) I used 1/4 inch carriage bolts. Tighten them firmly.

This radial arm saw breaks down into three major pieces for moving. Each weighs about 60 pounds (27 kg.), which makes each fairly easy to pick up and pack for moving. (We recently moved to a different house, which makes it convenient to do this Instructable now, since I did not need to take down my saw just to make photos, but could wait until I needed to take it down for moving, anyway.)

Each corner of the saw base has a mounting hole to be bolted down. 

Step 3: Install the Saw Arm

Rub some motor oil on the column surface on the saw arm. Lift the saw arm and let the column slide into its receiver. It also weighs about 60 pounds. Use the crank on the front of the saw base to bring the saw arm down a bit. At this point nothing holds the arm from rotating left or right.

See the second and third photos. Oil the shaft for the crank at both ends. The threaded shaft that raises and lowers the column needs some oil periodically, too. There is a hole on the arm above the column. Drip some oil into it now and then.

Step 4: Install the Key for the Column

In my hand I am holding the key for the column. This key keeps the column from turning left or right. The key is shaped like an hour glass. It fits inside the orange circle. A set screw on each side of the column casting (rear of the saw base) holds the key with just the right tension on it. See the yellow arrows. The left side set screw pulls the key toward the column. The right set screw keeps the key from being pulled too far into the column. You want the key to be tight in the column's keyway, but not too tight. Several attempts at tightening the set screws may be necessary to achieve satisfactory adjustment. The green arrow points to a screw that puts tension on a nylon button to add the right amount of drag on the column when it is cranked up or down. 

When you believe you have the key properly adjusted, grasp the knob on the end of the arm and try to move the arm right or left. (See the second photo.) There should be not discernible play between the column and its receiver. Yet, the arm should raise smoothly when cranked and without too much effort. 

Step 5: Prepare the Motor Yoke Assembly for Sliding Onto the Arm

The photo shows the top of the motor yoke assembly. The lever that tightens the yoke to prevent left or right rotation during use is the chrome arm under the yellow arrow. Pull it toward the back of the saw to loosen the yoke so it can be rotated. (A spring loaded release pin must also be raised and held. There is more about adjusting this release pin later in the discussion of removing heel.) Notice the two red lines. When the lever is tight, the lever should be behind the corner of the yoke by about the distance shown between the two red lines. As the saw wears, the lever will come closer and closer to the corner of the yoke when the yoke is tight. That can be adjusted. Notice the blue arrow. It points to a particular hole in a wheel full of holes. There is a locking screw in this hole. Remove it with an Allen wrench from beneath the yoke. Turn the wheel with the holes clockwise one or two holes and insert the locking screw from below again. The handle should now lock the yoke with the proper amount of space before it is too close to the corner.

Notice the four bearing rollers. The two marked with orange arrows have eccentric cams. As the mounting bolts are turned clockwise, the rollers move toward the center of the yoke assembly. Those indicated by the green arrows simply bolt to the top of the yoke assembly without any eccentric cams. These roller support the yoke assembly on the recessed ways in the saw arm. 

Note: On some slightly newer saws the bearing rollers are concave rather than convex. Instead of riding in recessed ways, they ride against round rods fastened to the sides of the saw arm. 

Step 6: Slide the Yoke Onto the Arm

There is a large Allen screw under the arm at the end near the adjustment knob. See the first photo. This Allen screw keeps the yoke assembly from rolling off of the end of the arm. Remove the Allen screw from the arm. Cradle the motor and yoke in both hands and guide the bearing rollers into the recessed ways on the arm. Put the Allen screw back in place and tighten it.

Make the electrical connections for the switch and install its mount on the top of the saw arm. (I use an aftermarket switch from Radio Shack on my saw because the original switch is no longer available from Sears. See this Instructable for details.) See the second photo.

Step 7: Set the Tension on the Bearing Rollers

Tighten the roller bearings with the eccentric cams. The yoke assembly should slide back and forth on the rollers easily and with the same amount of drag over the length of the saw arm. Place a hand under the yoke assembly and pull upward with some force. (See the second photo.) There should be no sensation of looseness between the yoke assembly and the saw arm. While two wrenches are visible in the first photo, my hand is not on one of them in order for me to be able to hold the camera for the photo. Try to make the tension on both the front and the rear bearing rollers as nearly the same as possible.  

Step 8: Choose the Electrical Service

This saw can operate on 115 or on 230 volts. The plate on top of the motor tells which wires to connect in order to switch from one voltage to another. The saw draws 10 amps at 115 volts, or 5 amps at 230 volts. The connections are to be made under this cover. I have never run the saw on 230 volts, but there are situations where that option would be an advantage.  There is also a reset button. I have had this saw 40 years. In that time I remember using the reset button once. I believe the blade bound up in something and the reset stopped the motor before I could reach the switch.

Step 9: Level the Table Support Rails

Two rails support the saw table. It is important for dado cuts, etc. that the height of the saw table relative to the arm be uniform. A high corner could destroy accuracy. Each rail is attached with two bolts, one near the front of the saw base and one near the rear. Loosening the bolts a little allows tapping the ends of the rails up or down just a little. The photo demonstrates the recommended way to set the rails. Rotate the motor in the yoke assembly so the shaft is vertical. Rotate the arm and move the yoke assembly on the arm until the shaft is directly above one of the bolts. Raise or lower the saw arm until one of the wrenches used for attaching the saw blade slides between the end of the motor shaft and the top of the rail with just a little drag. Lock down all adjustments to the motor yoke (adjustment knob at the end of the arm and the stop on the motor carriage) to eliminate possible error. Tighten the bolts on the rails when finished and check the position of the rails above each bolt again.

Step 10: Installing the Table

Place the saw table onto the support rails. Align the four bolt holes and bolt the table to the rails. 

The saw table has some movement when the bolts are loose. That can be used to adjust the front of the saw table (where the fence will be positioned) so it is exactly 90 degrees to the travel of the motor and yoke on the saw arm. See this Instructable where I added two blocks to the underside of the saw table and inserted screws through them to make alignment blocks. The tips of the screws ride against the frame of the saw base and allow instant, precise alignment once the screws in the blocks have been adjusted after initially adding the blocks.

Note: It can happen that one of the rails from the previous step is too far forward and the holes in the table do not align with the holes in one of the rails. It may be necessary to repeat the previous step while moving one rail forward or backward a little.

It can also happen that someone acquires a radial arm saw, but the saw table is missing. You can make your own from a flat piece of 3/4 inch MDF or plywood. Here are the dimensions for a Sears Craftsman saw like mine. (See the second graphic.) The original saw table is 3/4" x 19" x 36". (After almost 40 years of cut marks I made a new table 48 inches wide.) You need four 3/8" dia. holes. Also drill into each hole to make a countersink for the bolt heads. This should be deep enough that the blade will not reach them during use. The first pair are set back from one edge of the table 1 1/8" on center. The second set are set back from the same edge 11 1/8" on center. Each hole is 8 1/4" in from both outer edges. In addition to the basic table you need a fence 3/4" x 1 1/2" x 36" and a support piece behind the fence that is 3/4" x 5" or 6" x 36".

Step 11: Adjust the Motor Tilt

Set a square against the blade to see if it is square with the table when set at zero degrees. In the first photo you can see a gap at the top of the square. The four Allen screws visible need to be loosened. The bottom two screws are not accessible until the locking knob is removed. Loosen all four screws.

The motor is heavier on the right side and it will sag. A neat trick to make aligning the motor tilt easy is to put a block under the right side of the motor. The crank that raises and lowers the column can be gently tweaked to make the blade parallel to the leg of the square. Put the locking knob back into place. Leave it loose. Push the handle in a clockwise direction to take out the play. Tighten the adjustment knob. Gently tighten the top two Allen screws, alternating between them. Remove the knob and tighten the two bottom Allen screws. Insert the knob again. Swing the motor into place and lock the knob.* Check the blade with the square. Adjust the pointer on the degree scale, if necessary.

*When I bought my saw in the store the motor tilt knob would not lock the motor in place. The internal mechanism consists of a metal wedge pushed inward by the knob. See the third graphic. The sides of the wedge push two sets of two nylon cylinders outward against internal castings. The nylon cylinders next to the metal wedge have a square end and a rounded end. One of these had been inserted backwards at the factory. I had to remove the motor from the yoke. Paint marks on the rear pivot of the motor helped me get the motor back into place again.

Step 12: Check for Fence to Arm Alignment

Use a good square to check the travel of the blade so it is at 90 degrees to the fence. Pull the motor down the length of the arm. The blade should lightly touch the square the length of travel. Flip the square over and check from the other side of the blade, too. See this Instructable for a more precise way of checking by cutting two square pieces of thin plywood simultaneously, flipping one over, and checking to see if their edges meet consistently or if they form a "V."

As you can see, my saw does not have the floating blade guards seen on newer saws. Someone will surely comment that there has been a recall on these saws and free floating blade guards are available. That is true for some older saws, but the serial number on mine is not included as eligible for that offer. A government video to illustrate the alleged dangers of a saw without the floating blade guards shows the operator with his hand flat on the table in the path of the blade. No one with any intelligence would ever place his hand in the path of the blade like that. (The proposed floating blade guards would not save a hand firmly on the saw table in front of the blade travel, anyway.) According to the government, those of us who have this saw are supposed to cut the electrical cord to the motor and mail a 60 pound yoke assembly to the manufacturer for a $100 rebate. I prefer to keep my hands away from the blade and continue to use the saw just as I have done very safely for the last 40 years.

Step 13: Check for Heel

"Heel" means the blade moves through the wood cocked a little to one side. Heel results in burn marks on at least one side of the cut. You can also detect heel when the blade kicks up splinters as it exits the cut at the rear of the cut. 

Use a framing square to check for heel. Set one leg against the fence. Bring the other leg against the saw blade. If there is no heel, the square and the saw blade will meet consistently from the front of the blade to the rear. If there is a "V"-shaped gap, the blade has some heel that will need to be removed. (The hammer in the first photo is supporting the square so I can check for heel below the motor shaft for more accuracy.) 

In the second photo my finger points to one of the two bolts that lock down the indexing pin mount. Loosen these two bolts a moderate amount and the pin mount can slide left or right. Hold the indexing pin up and rotate the yoke until the square indicates the heel is gone. Gently lock the yoke in place. Push the indexing pin mount to the right of the photo and lock it down with the two bolts. Loosen the yoke and swing it back into place. Tighten the yoke lever. Check settings with the square again. (The most certain test is to make some cuts in some wood and see how the saw performs.)

This can be a very tedious process. I think I have it just right, but when I loosen the yoke and swing it into position against the indexing pin, I learn I am "off" a fraction of a degree, perhaps more. I have found a fine adjustment is not too difficult if I tighten the knob that locks the yoke assembly in place on the arm, loosen the chromed lever that locks down the yoke, pull the yoke pin about halfway out of its socket (It is tapered, which allows some control over how much the yoke can turn under these conditions.), turn the yoke against the pin in the desired direction, lock the yoke with the chromed lever, loosen the indexing pin mount bolts, allow the pin to settle in its socket, slide the mount as much as possible in the required direction, and lock down the mount bolts. Then swing the yoke into position again and check alignment. (See the third photo for a helpful set up. When using this set up, move the square to the other side of the motor and check the reading on the rule. Tweak until the reading from both sides is the same.) 

Mechanical things do wear. Indexing holes that were once precise can wear at differing rates so that a saw adjusted for good crosscuts with no heel show quite a bit of heel on rip cuts. See this Instructable for my relatively simple solution to restore accuracy to the indexing holesthir.

All radial arm saw adjustments have some play in them. The suggestion is to set the saw up so that you always remove play by nudging the part being positioned in the same direction. I chose always to take the play out by nudging the parts in a clockwise direction. That means sliding the pin mount to the right in the photo before locking it down with the bolts after the chromed lever on the right side of the saw was loosened and the yoke was rotated to remove any heel so the chromed lever could be tightened again.

Make some crosscuts and some rip cuts in some scrap wood and check the cuts for heel and for square. If everything went well, you now have a very precisely adjusted radial arm saw. As mentioned in the Introduction, radial arm saws do go out of adjustment through use, through moving them, and through knocks and bumps that seem to be inevitable in a workshop. Most users will check all of the major settings for accuracy before beginning any important special project. It is important to set up the saw in the steps shown here because later settings are dependent upon earlier settings being precise.