Table saws are a fantastic asset in any woodworking shop; in fact, the number one tool in any shop in the United States. Able to break material down into manageable sizes to 1/64” precision, cut accurate miters and bevels, and create dozens of common and unique woodworking joinery tasks. Of course, all of this greatness can only be achieved if the saw is set up correctly! A task that honestly should take less than 30 minutes every few months or so and is well worth your time!
Everything starts at the blade. The accuracy of the fence, miter slots, and any accessories that ride in those slots are based on the blade. So, let’s start there. A bent or misaligned blade will cause a wider kerf, kickback, and generally inaccurate cutting. So first we want to check the runout on the blade or make sure that it rotates without any “slop”. When you mount the blade on the arbor spindle, it will come to rest against a fixed washer. As you put the blade on (with the saw unplugged), visually check that fixed washer for any burrs or dirt that would keep the blade from fitting tight against the washer. Then mount the blade, outside washer and nut, tightening as you would for operation.
Since we haven’t aligned the miter slots yet,
we’ll use a magnetic-based dial indicator to
check the runout. Raise the blade to its maximum height and mount the dial
indicator so that the spring-loaded stylus indicator is touching the body of
the blade just below the carbide teeth, not the teeth themselves. Then manually
reach inside the saw and slowly turn the blade by moving the belts (turning by
the blade will affect the reading). Watch the dial readout, and regardless of
the setting, it should not vary much at all as the blade is rotated. If it does, something isn’t right,
and it’s time to check the blade for flatness, and both the blade and the
mounting washers for debris.
With the blade running square on the arbor, we
can now check the miter slots against the blade. This involves a similar
process as checking runout, but in this case we want to register our dial
indicator in the miter slot. We’ll use an EZ-Align
Alignment Gauge that has a bar attached designed to adjust fit snugly in
the miter slot, giving an accurate reading. Rather than measure from the top of
the blade, we’ll measure in three locations against the blade body. First, a
measurement in the middle of the blade.
Note the dimension shown or adjust the dial indicator to read an easily read
dimension. Then move the alignment gauge to both the infeed and outfeed edge of
the blade, taking measurements at both locations. If there are variations in the measurements, it means your saw’s table is misaligned with the arbor. Adjusting the table isn’t always an
easy task, and usually requires loosening bolts under the top that attach the
top to the motor assembly. You should read your saw’s instructions to determine
how this is done, as each saw will have slightly different adjustment methods.
Most table saws have two miter slots, so it’s a good idea to do a quick check
that they are both correctly aligned with the blade. You can also simply
measure between the two slots to make sure the distance between is the same at
the front and rear of the table saw’s top.
With the miter slots (and thus the table itself) in parallel with the blade, it’s time to square the fence to the blade. Once again, we’ll use the EZ-Align alignment gauge in one of the miter slots. There are a number of articles that will tell you that exact parallel may not be what you want for setting your fence, (the idea that toeing the fence away from the blade slightly on the outfeed side will reduce binding). It’s my experience that when you have the saw properly aligned and the fence parallel to the blade, binding isn’t a concern. So, you want to take a measurement at the infeed and outfeed points of the blade against your fence. Make sure the fence is locked firmly in place while taking the readings. If there is variation, again use your manufacturer’s instructions to adjust the fence until the readings match.
One of the benefits of using a table saw is being able to tilt the blade to make angled cuts. Some blades will tilt to the left, and others will tilt to the right. Regardless, two significant settings should be accurate when tilting the blade: the zero – or straight – setting, and the 45° setting. These settings are commonly a bolt with a jam nut in two locations on the front trunnion of the table saw. Again, a little tricky to dig into the saw and find, but your instructions will tell you where to look. But first, let’s see if you need to adjust the bolts. With your blade not tilted at all (straight up and down) and firmly against the 0° setting, use either an angle cube or an engineer’s square to check the angle of the blade. In the photo, I’m using both because I found that the angle cube accurately told me that my floor wasn’t flat, so I adjusted the blade to the square, then used the zeroing function of the cube to set zero. If you’re not getting a 0° reading, or see light through your square, you’ll need to adjust that set screw on the trunnion. Next, tilt the blade to 45° and again use the angle cube to check the setting. Adjust as necessary.
Now let’s move back to the fence and make sure that your fences’ indicator scale is reading correctly. Set your fence to an easily-read dimension (3”) using a steel rule, or a set-up block and measure between the fence and the teeth of the blade (not the body this time as the cut happens at the teeth). If your reading is inaccurate (I’m slightly off in the photo), adjust the scale according to the manufacturer’s instructions.
One last set-up step, but a critical one. As material is pushed across the tabletop, it naturally passes over the throat plate. If the plate is higher than the tabletop, wood can catch and interrupt the cut. If the plate is lower than the tabletop, the material can dip and again interrupt the cut or bind material against the blade. Both situations are dangerous and will lead to inaccurate cuts. Use a straight edge to check across the throat plate at multiple locations to make sure the plate is perfectly aligned with the table or err to being slightly below the table height as this is less hazardous.
As we use our saws, things can move out of alignment. These simple check-up steps will keep your saw safe and accurate if repeated on a regular basis. And, of course, keep things clean and sharp for the best operation and accuracy.
- David Thiel