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Before aligning a table saw fence, first check that the blade is parallel to the miter slot. The fence can be perfectly straight and still burn wood, pinch stock, or cause kickback if the blade points slightly toward or away from the slot. This check also prevents you from “fixing” a blade-parallelism problem by skewing the fence.
What you are checking
The goal is to compare the blade’s position at the front and rear of the table saw relative to one miter slot. You are not checking whether the fence is parallel yet. You are checking the saw’s trunnion or table alignment, depending on the design.
For most cabinet and contractor saws, a practical target is within about 0.003 to 0.005 inch from the front of the blade to the rear. Some manufacturers allow more, and many saws will cut acceptably at roughly 0.010 inch, but tighter alignment reduces burning and binding. The blade should usually be set parallel to the slot, or very slightly farther away from the slot at the rear. A rear edge that points toward the slot is the dangerous direction because it can pinch the work against the blade.
Tools needed for the check
Unplug the saw before removing the throat plate or reaching near the blade. You need a clean blade, a reliable reference, and a way to measure the difference. A combination square works for a basic check, while a dial indicator gives more useful numbers.
- A sharp combination square or a table saw dial indicator alignment gauge
- A pencil or fine marker
- A tape measure or ruler for rough checks
- A hex key or wrench for the trunnion mounting bolts, if adjustment is needed
- A clean, flat-toothed or ordinary carbide blade
Do not rely on a cheap tape measure for a few thousandths of an inch. It is useful for confirming that you are measuring at the same points, not for measuring the actual error.
Prepare the saw before measuring
Disconnect power and remove the fence. Clean sawdust from the miter slot, table surface, arbor flange, and blade. A chip under the blade flange can create apparent wobble. Check that the blade is fully seated and that the arbor nut is snug, but do not overtighten it.
Raise the blade to its normal cutting height, typically with the gullets about 1/8 to 1/4 inch above the workpiece. A higher blade exposes more tooth movement and makes the check easier. Lock the blade height and bevel at 0 degrees. Confirm the blade is actually vertical with the saw’s bevel scale or a reliable square.
Pick one tooth near the front of the blade and mark it with a pencil. Rotate the blade by hand until that same tooth is at the front measurement point. Using the same tooth matters because carbide teeth are not always set identically around the blade.
Choose a measurement method
| Method | Typical precision | Best use | Main drawback |
|---|---|---|---|
| Combination square | About 1/32 inch, depending on technique | Quick check or rough diagnosis | Hard to distinguish blade wobble from alignment error |
| Steel rule or feeler gauges | About 0.005 to 0.010 inch | Low-cost, repeatable setup | Requires careful contact without touching the tooth edge |
| Dial indicator | About 0.001 inch | Accurate alignment and troubleshooting | Costs more and must be mounted rigidly |
A precision combination square is fine for many jobsite saws. If you routinely cut hardwood, use a dado set, or are correcting a persistent burning problem, a dial indicator is worth the extra cost. The cheaper option is fine when you only need to find a major misalignment.
Check with a combination square
Set the square’s head against the left edge of the miter slot. Extend the rule until it reaches the marked tooth, then lock it. The rule should touch the tooth lightly without pushing it sideways. Rotate the blade so the marked tooth is at the rear of the blade, then slide the square to the same position and compare the gap.
Do not drag the square across carbide teeth. Contact the tooth face lightly, or use the body of the blade just below the teeth if the square can reach it. Repeat the front and rear readings two or three times. If the gap changes when you rotate the blade, you may be seeing blade runout rather than trunnion misalignment.
Check with a dial indicator
Mount the indicator to a miter-slot bar or other rigid fixture. The indicator tip should touch the blade plate just below the teeth, not a carbide tooth. Zero the indicator at the front of the blade, then rotate the blade so the same marked tooth reaches the rear. Slide the fixture only if necessary and record the reading.
Take readings on both sides of the blade. If both sides show a similar front-to-rear change, the blade assembly is likely out of parallel with the slot. If one side shows much more movement, inspect the blade for warping, dirty flanges, or arbor runout. Rotate the blade through several positions and repeat the test; a bent blade will often produce a repeating high and low spot.
For a useful diagnosis, measure the blade at the front, rear, and at least one intermediate position. A steady change indicates alignment error. A wandering reading indicates runout, tooth-set variation, or a loose measuring setup.
Interpret the result before touching the fence
If the rear of the blade is farther from the slot by 0.003 to 0.005 inch, leave it alone unless your saw manufacturer specifies otherwise. If the rear is closer to the slot, correct the blade alignment before aligning the fence. A 1/32-inch error is large enough to cause visible burning and should not be compensated for with the fence.
Adjustment varies by saw. On many saws, you loosen the trunnion bolts slightly, tap the assembly with a rubber mallet, and retighten while rechecking. On others, the table moves relative to fixed trunnions. Make small changes—often only a light tap is needed—and tighten bolts gradually so the assembly does not shift back.
Recheck before aligning the fence
After adjustment, reinstall the throat plate and repeat the measurement with the blade at 0 degrees. Check again after changing bevel angle if your saw’s trunnion design can shift during tilting. Only when the blade is parallel to the miter slot should you align the fence. Then measure the fence at its front and rear, keeping it parallel or opening slightly toward the rear according to the saw and fence manufacturer’s instructions.