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
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
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
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
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
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
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
Step 8: Choose the Electrical Service
Step 9: Level the Table Support Rails
Step 10: Installing the Table
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
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
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
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.