3 ways to accurately align a rip fence
Here are 3 methods that show you how to align a rip fence.
- Use a drop dial gauge
- Use your miter gauge + a piece of wood
- Square a piece of lumber the size of the miter slot extending higher
These methods are listed from most accurate to least accurate.
Things You Should Know
- A drop dial indicator is the most accurate method to align your rip fence. Although, be wary of cheap gauges on Amazon.
- -0.005" (0.127mm) is an ideal front to back variation for a cabinet table saw fence. This number may be greater for saws of less precision.
- Plan on spending 1-2 hours to perform this task if this is your first time.
- A list of all the tools and materials needed can be found at the end of this article.
How to align your table saw rip fence with a drop dial indicator gauge
1. Set up the drop dial indicator in the miter gauge slot
Position a drop dial gauge in the center of your miter slot that is to the right of the blade. Ensure there is no play, slop, or movement with where the gauge sits in the miter slot.
I would recommend purchasing an aluminum mount to place in the miter slot. Be sure to tighten the screw holding the indicator snug.
Table Saw Indicator Gauge | No Brand
DURABLE MATERIAL: The Table Saw Gauge is made of Aluminum Alloy which enable it to last long and still give accurate measurement.
I took the indicator that was included with this Amazon purchase and replaced it with a Mitutoyo digital gauge. The included indicator fell apart within just a few uses, so I opted for a professional option that is more accurate and easier to read. The aluminum mount was all that I needed anyway.
The important thing to remember is to ensure there is no lateral movement while the indicator is in the miter slot.
We’re dealing with hundredths and thousandths of an inch. Any lateral variance in the miter slot will produce an inaccurate result.
2. Move the fence to touch the gauge
Once you’ve established a secure fit for the indicator in the miter slot, move it as far forward (closest to the front of the saw) as you can.
Move the fence toward the indicator just so that it moves the indicator in about 5mm to 8mm. Lock the fence in place.
This is about the width of a couple nickel stacked on top of one another.
If you are using a digital indicator, zero it now, otherwise for an analog indicator, rotate the face so that you align 0 with the hand.
3. Move the indicator and take notes
Slowly move the indicator along the miter slot to the rear of the table saw, being careful not to cause any lateral movement. Stop to take a measurement in the middle of the fence and again at the end.
Perform this process 3-5 times to verify your results.
4. Analyze the data and make adjustments as needed
How to interpret the data
- A negative measurement indicates your fence moves away from the miter slot when measuring front to back.
- A positive measurement indicates your fence moves toward the miter slot when measuring front to back.
- A 0.000 measurement means your fence is very close to perfectly square to the miter slot
For a cabinet saw, your fence would have a negative measurement of about 5 thousandths of an inch (0.005”) or about 0.127mm.
For a jobsite saw, like the ones pictured, achieving a -0.010" variation is very good, but not necessary. Generally, a negative variance anywhere from -0.010" to -0.0180" will be more than adequate.
The important factor to note here is that the measurement is negative. Since you started the measuring at the front of the miter gauge, this means that the fence gets farther away from the miter slot as it approaches the end of the table top.
This is what you want. Because having just a hair (or actually a couple of hairs) helps to prevent the workpiece from getting pinched at the end of the cut, which may cause kickback.
The fence will never remain perfectly square to the miter slot, even if you got it there according to your indicator. Therefore, if we’re going to error on the safer side, then we should leave the end of the fence slightly open.
What if the result is positive?
If your measurements consistently read as a positive from front to back, then your fence is likely pinching your workpiece against the blade (or at least the miter slot) as you make a cut.
This is dangerous.
Any situation where the cut piece is being pushed towards the rear of the blade creates the possibility of:
- Kickback
- The cut piece flying towards you, the user
- Your hand or fingers getting pulled into the blade
While all modern table saws have a riving knife that is pre-installed to help prevent this, kickback can still occur. This is especially true if there is significant variance on the arbor or the saw blade that contributes to the ‘pinching’.
Immediately adjust the fence so it has a negative measurement from front to back.
How to align a table saw rip fence with your miter gauge
1. Drill a piece of wood to your miter gauge
Ideally the piece of wood is square on at least one end; however, it doesn't have to be perfect. I am using a piece of wood that I squared up on the jointer and used as a clamping square for another project.
2. Run the gauge and wood along the miter slot
Slowly, run the gauge along the miter slot, keeping it snug against the left hand side of the slot. You will see a gap start to form between the wood and fence, or the ruler will start to grind against the fence.
If you feel friction, this tells you the fence is closer to the blade as you move towards the rear of the table. If a gap forms, the fence moves away as it moves towards the back of the table.
3. Adjust the fence and re-test
To re-align the fence after discovering the gap is too large or too small, you'll need a a piece of paper or a playing card
Start with the gauge flush with the fence at the front of the table saw. Run the gauge front to back and get the fence zeroed to the best of your ability.
When the fence is square to the miter slot, take a piece of paper folded in half, (or a single playing card) and use it as a shim to make your rear alignment.
The front of the fence will be square and even with the gauge. The rear will be even and square with a piece paper between the fence and combination square.
After aligning the fence with the paper shim, I took the drop dial gauge to see how accurate it was. The fence measured at a -0.0140" (0.3556mm). While 0.010" is ideal, being 0.004" off with a piece of paper and a 2x4 is a good result.
How to align your table saw rip fence by squaring a tall miter slot runner
1. Cut a hardwood runner and square it up
Cut a piece of hardwood so that it will fit into the miter slot and extend approximately 1 inch to 2 inches above the slot and table surface. You will need to use a jointer or planer to ensure it’s perfectly square.
2. Place the runner in the miter slot and place the fence up against the runner
Insert this runner into the miter slot
Align the rip fence so that is square to the runner and lock it into place.
3. Look for any gaps and adjust as needed
From an overhead view, look down to see where there is a gap.
Adjust the rip fence as necessary.
If the gap is difficult to see, use a piece of paper, possibly folded, to feel for gaps.
Materials and Tools Needed
Materials
- 3 pieces of copy paper
- Straight piece of hardwood about 1" thick
Tools
- Drop dial indicator gauge
- Combination square
Jobsite saws vs. cabinet saws
Five thousandths of an inch of negative variation is ideal, but it’s not always possible to achieve, especially on entry-level, jobsite, or older table saws. For example, the overall fence quality on a jobsite saw is less than that on a professional cabinet saw.
The cost of only the fence on a professional cabinet saw can easily exceed the cost of a complete jobsite saw.
If you can achieve 10 thousands of an inch (0.010”) of negative variation on your jobsite saw, that will typically suffice.
Be aware of tolerance stack up
Nothing is ever perfect and that includes the miter slots, the fence, the blade, the arbor, your tools, and your measurements. Being off a little here and a little bit there eventually adds up.
How to adjust the rip fence
For most table saws, there are a couple screws with an allen head in the front and rear of the fence. These screws must be loosened to move the fence left or right.
For example, on the Dewalt DWE7491RS jobsite saw and the SawStop CTS120-A60, we can see these few screws are used to adjust the left or right lateral variance of the fence.
FAQ
Why measure from the miter gauge slot and not the blade?
The miter gauge slots will remain in the same location for every single measurement. Whether we’re measuring to the blade or to the fence, the miter gauge slots are constant. The blade is not constant. The blade and the arbor may have variation from one measurement to the next, which will not produce accurate results.