INDUSTRIES

Table Saw Test #3
Checking Table Saw Alignment

One of the most frequent problems that table saw owners approach us with is on table saw alignment. With the average table saw, whether it is a "contractor" style (with the motor hanging out the back) or a large cabinet saw, this procedure can be a very frustrating experience. If you don’t have the proper tools and a good understanding of exactly what needs to be done to accomplish the job accurately, you’re probably only going to make problems for yourself by attempting to do an alignment procedure on your saw. Before I tell you how to approach your saw’s alignment problems, let me explain a couple of things that I did wrong, just to save you some headaches:

When I bought my first new saw (what is now my old Sears saw) in 1976, I was very disappointed with the way it cut "right out of the box". I decided to go through the manual and try to fix the problem. Well, I created more problems than I fixed! I loosened the bolts in both the front and rear trunnions, just like the manual told me to. I took my little adjustable square and placed one side of it against the side of one of the miter grooves that was toward the saw blade. I adjusted other side of the square until it made contact with one of the teeth on the saw blade. As I slid the square toward the back of the saw, I noticed a gap between the square and blade tip at the rear. I grabbed a hammer and piece of scrap wood, (which were the "fine-adjusting tools" recommended in the manual), and gave the rear trunnion a "tap" in what I thought was the correct direction. As I tried (for a couple of hours) to re-tighten the bolts, the trunnions kept moving. The bolts were dragging on the slots in the trunnion. Well, when I finally got things in what I thought was a good alignment, the saw cut worse than it did before I started!

Here’s where I had gone wrong:

1. I was not using proper methods of alignment as I slid the square along the plate of the saw blade. I made the assumption that the flange of the arbor was perfect, and that the saw blade was, too. If you performed Table Saw Test 2, (Arbor Flange and Blade Runout) you probably know by now that they may be very close, but not necessarily perfect. The arbor flange on my old Sears produces about .004" runout, and the blade that I got with the saw probably produced .008" - .010" runout. By referencing these two things, what I had done was throw my saw completely out of alignment!

2. I never should have loosened both trunnions on the saw at the same time.

What you are actually trying to accomplish when you align your saw is to position the arbor shaft perfectly square to the grooves in the table saw top. By doing this, we will accept the fact that there may be a little runout in the flange of the arbor and the saw blade, but the cut that is being made by the saw blade is perfectly parallel to the grooves in the saw. To accomplish this, we must use a specific point on the saw blade as a reference toward the front of the saw. We then rotate the saw blade toward the rear of the saw, and use this same point as we take any readings. By doing this, we can determine how far "out of parallel" the tips of the blade are with the grooves in the top of the saw because of improper squaring of the arbor shaft.

Only have one trunnion loose at a time. With the entire mechanism "hanging" below the top, almost any time that I touched something the mechanics shifted, causing more problems. If you are aligning a contractor style saw, loosen only the rear trunnion to make adjustments. If you can’t get the saw to align in this manner, then (with the rear trunnion locked down) you should loosen the front trunnion, give it a "tap" in the proper direction, and re-tighten it into position. You should then loosen the rear trunnion, and make adjustments as needed on the rear trunnion.

It’s almost impossible to adjust a contractor saw accurately. A hammer and block of wood can hardly be called a "micro-adjusting" system. If you want to get your contractor saw aligned perfectly, the easiest way that I know of is by installing our Precision Alignment and Locking System ("PALS"). This simple kit is available for most popular brand contractor saws, and allows you to adjust your saw with an Allen wrench, not a hammer. An added benefit to this kit is that when it is properly installed, it "locks" the rear trunnion into position, preventing the saw from coming out of alignment. You will find more information on this innovative product on the PALS page.

A saw with vibration problems is very difficult to keep aligned. Most of the vibration in a contractor saw is produced by inferior pulleys and belt provided with the machine. By installing our Contractor Saw Performance Package, with the machined steel pulleys and Power-Twist belt, you will not only decrease vibration by 80% - 90%, you will actually improve the overall performance of the saw. This also helps keep the saw in proper alignment.

Most table saw owners normally use the left guide slot when they are doing mitering or "cross-cut" work. I would recommend that you use the guide slot you normally use for these cuts when you check the alignment of your saw. If you have a contractor style saw, you should install the PALS System and Contractor Saw Performance Package prior to starting alignment. Assemble the A-LINE-ITÔ as shown in the photo. Be sure that the spring plungers in the "Smart Bar" are on the side of the guide slot furthest from the saw blade, and are pushing the bar toward the "blade side" of the slot. Pivot the dial indicator down to position the tip of the indicator near the top of the saw, and lock it into position by tightening the Allen screw that secures the indicator to the mounting bar. (This increases the distance where the measurements are taken, and maximizes the error shown on the indicator.

The following procedure will allow you to check (and set) arbor shaft and guide slot squaring.

1. With a blade installed on the saw, elevate the arbor to its maximum height, and then lower the arbor 1û4" or so.

2. Assemble the A-LINE-IT™ as shown in the photo, and position it into the guide slot that you want to use during the alignment procedure. Pivot the dial indicator downward, and place the tip as close to the saw top as possible without actually making contact with the saw top.

3. Using a felt tip pen, place a mark near any tooth on the blade that you want to use as a reference during the test. (I would recommend that you do not put the mark on a carbide tooth, but on the plate close to one. This gives us as large a reference as possible during the alignment procedure.)

4. Rotate the saw blade, and place the market tip toward the front of the saw.

5. Slide the A-LINE-IT™ to a position that allows you to place the tip of the indicator on the mark on the blade.

6. Zero the dial indicator.

1.  Slide the A-LINE-IT™ toward the rear of the saw as you rotate the blade backward with your other hand, and position the tip of the indicator on the mark on the blade as shown in the photo to the left. Note the reading on the dial indicator.

If you are really lucky, the reading at the rear will be within .002" (two thousandths of an inch) of zero. If it is, I would re-test the squaring, consider myself very lucky, and leave things alone. If it ain’t broke, don’t fix it!

If you are like most saw owners, the reading at the rear will be over .002", and should make a correction to the saw.

Let’s cover briefly what the dial indicator is telling us by these readings:

1. If the reading at the rear of the saw went negative (under the zero line), the distance between the saw blade and the guide slot is longer at the rear than it was at the front. The blade needs to be moved closer at the rear.

2. If the reading at the rear of the saw went positive (above the zero line), the distance between the saw blade and the guide slot is shorter at the rear than it was at the front. The blade needs to be moved away at the rear.

The chart below will tell exactly what action must be taken, depending on the type of saw you own and the type of reading shown on the dial indicator. Readings and adjustments are made as viewed from the front of the saw.