Squaring a Table Saw Sled Fence

Clicking on the small images will enlarge them.

Aligning a table saw sled fence to 90 degrees can be a frustrating, hair pulling event. However, if you follow the following tip, it can be a breeze. Sure, there are other methods to align a table saw fence to 90°, but most require making test cuts with plywood and are less accurate. Aside from being less accurate, the other methods take longer to get an accurate 90°. I don’t know about you, but I’d rather be spending my time making projects than trying to align my tools. Speed is the major advantage here, accuracy just comes along for the ride.

Step One:
  • Watch a video of the process!
  • First, place a dial indicator w/ a magnetic base on your table saw fence or table saw surface.  I like to use the table saw fence because I can lock the dial indicator on the TS-fence and move it into the square.
  • Temporarily secure the sled fence to the sled. Next, place a good quality square against your sled fence and zero the indicator at the top of the square.
Step Two:
  • Now slide the sled forward and take an indicator reading at the bottom of the square. If you don’t read zero at your second measurement, you are not square. Adjust the sled fence and re-measure.
  • You can also rip pieces of plywood and measure with a caliper the two ends of the strip you rip off. This method is less accurate, wastes plywood and takes longer.
  • You can also use a TS-Aligner Jr. (see my review) and do the same thing (only this time you will need to secure the aligner to your TS because the aligner doesn't have a magnetic base.)

 
  • Quick Tip:  My fence is attached to the right side with a screw. On the left side I have two bolts w/ wing nuts. The bolts are in slightly elongated holes in the fence so that the fence can move forward and back in small amounts. Once I have it aligned, I tighten down the two wing nuts. So far it has been working just fine.
  • Close up.
   
 

With a dial indicator that measures to 0.001” (most inexpensive ones) and a 6” square you can detect as little as 0.0095 degrees error. Using a longer square will increase the accuracy.

Boring math: arctan (0.001”/6”) = angle error = +/- 0.009 degrees rounding down.