How to Adjust the Trunnion on a Table Saw

Attach the dial indicator to a piece of 3/4-inch thick wood that will act as a crossbar. Clamp the set up into the miter gauge of your table saw and slide the gauge into the miter slot milled closest to the saw blade.

Unplug the table saw and leave it unplugged throughout the process of checking parallelism of the blade and adjusting the trunnions.

Raise the blade as far up as it will go, then back it off about 1/4 turn to relieve a little pressure that could impact your readings. Make a mark on the body of the saw blade just behind one of the teeth using a marking pen.

Rotate the blade forward and slide the miter gauge so that the mark aligns with the dial indicator. Contact the indicator's plunger with the mark and set the dial indicator to zero.

Rotate the blade backward, push the miter gauge forward and align the dial indicator with the mark. Note the difference between this reading and the one at the first location. If the difference is greater than .003 inches in either direction, the trunnions need to be adjusted to realign the saw blade parallel to the miter gauge slot.

Loosen the bolts for the rear trunnion on the underside of the table using a wrench. Loosen one bolt on the front trunnion and loosen the other only slightly, just enough so it is still snug but not tight. This last bolt will create a pivot point.

Tap the back trunnion left or right, depending on which way the blade needs to move to true it. Hold a scrap block of hardwood against the trunnion and tap lightly with a rubber mallet. Not much force is needed to move the trunnion and the wood helps protect the device from damage. This process may need to be repeated several times to get the blade within .003 inches of running parallel to the miter slot. Adjust, measure the mark with the blade in both positions, note the difference and adjust again as needed.

Tighten the trunnion bolts in a pattern similar to the way a tire is bolted onto a car. Tighten each bolt a little, then move to the opposite bolt. When the bolts are snug, check for parallel again to make sure the trunnions did not shift while being tightened. If all is well, finish tightening the bolts the rest of the way. If not, loosen them and repeat the adjustments.