How to Change a DeWalt Miter Saw Blade (Reverse-Thread Bolt)
DeWalt miter saw arbor bolts use a reverse (left-hand) thread — turn the bolt clockwise to loosen and counterclockwise to tighten, the opposite of a standard bolt. Fighting it the wrong direction for even a few minutes is the most common mistake, and forcing it can strip the bolt head or crack the guard bracket. This guide covers the exact spindle-lock procedure, correct blade orientation, and the DWS779/DWS780-specific bolt access DeWalt’s own manual describes.
What You Need Before You Start
Most DeWalt miter saws ship with a hex or spanner-style arbor wrench clipped to the base or stored under the handle — that’s the only specialty tool required. Newer models (DWS779, DWS780) use a Torx T30 or T40 screw on the blade guard bracket; older saws (DW713, DW715) typically use a Phillips #2 screw instead. Check your saw before you start so you’re not mid-swap when you realize you have the wrong driver.
- Included arbor wrench (or a 13mm / 15/16″ socket wrench as a backup)
- Torx T30/T40 driver (DWS779, DWS780) or Phillips #2 (DW713, DW715, and older models)
- Replacement blade matched to your saw’s arbor size — most 12″ DeWalt miter saws use a 1″ arbor
- Safety glasses and work gloves
How to Change the Blade on a DeWalt Miter Saw (Step-by-Step)
Follow this order exactly — skipping the spindle lock step is the main reason people round off the arbor bolt or spin the blade while trying to loosen it.
- Unplug the saw. Corded saws: pull the plug completely, don’t just flip the switch. Cordless saws: remove the battery.
- Raise the arm and pull the locking pin. Raise the saw arm to its highest position and pull the locking pin so the head stays up on its own.
- Loosen the blade guard bracket screw. It sits just in front of the arbor bolt. Turn it about two turns counterclockwise, then lift the upper blade guard as far as it will go.
- Press the spindle lock. Rotate the blade slowly by hand while pressing the spindle lock button (on the right side of the blade housing on most models) until it clicks and the blade stops turning.
- Loosen the arbor bolt — clockwise. With the spindle lock held in, turn the arbor bolt clockwise with the included wrench. This is the reverse-thread step people get backwards.
- Remove the bolt, washer, and old blade. Set the bolt and outer washer aside somewhere they won’t roll away, then lift the old blade off the arbor.
- Install the new blade. Seat it on the arbor with the teeth at the bottom-front of the blade pointing down and toward the rear of the saw — the same direction the blade rotates when cutting.
- Tighten the arbor bolt — counterclockwise. Replace the outer washer, hold the spindle lock, and thread the bolt in counterclockwise until snug. Don’t overtighten — the reverse thread keeps it secure under normal cutting load.
- Reassemble the guard and test. Release the spindle lock, lower the upper guard back over the blade guard bracket screw, and re-tighten that screw. Plug the saw in and spin the blade by hand once before making a test cut.
Why DeWalt Uses a Reverse-Thread Arbor Bolt
A reverse (left-hand) thread is a bolt design that tightens in the opposite direction of a standard bolt so that a spinning blade’s own rotation cannot loosen it. Since a miter saw blade spins clockwise when cutting, a normal right-hand bolt would gradually work itself loose under that load. DeWalt (like most compound miter saw makers) cuts the arbor bolt with a left-hand thread instead, so the cutting motion keeps tightening it rather than backing it out. The same reverse-thread logic shows up on corded circular saws too — see our Skilsaw blade-change guide for a side-by-side comparison.
DWS779 and DWS780 Spindle Lock Location
On the DWS779 and DWS780, the spindle lock button sits on the right side of the blade housing and must be depressed while you rotate the blade slowly by hand until it engages — DeWalt’s own instruction manual for these saws specifically warns never to depress the spindle lock while the blade is under power or coasting to a stop. The blade guard bracket screw on both models is a Torx T30, not a hex or Phillips, which trips up owners used to older DeWalt saws.
Choosing the Right Replacement Blade
Match the diameter first — most compact DeWalt miter saws take a 10″ blade, while full-size compound and sliding models (DWS779, DWS780, DW716, DW717) take a 12″ blade with a 1″ arbor hole. Installing an undersized blade reduces cutting depth and throws off the guard fit, so don’t downsize just because a smaller blade was on sale.
After diameter, tooth count decides the cut quality: a 32–40 tooth blade rips faster but leaves a rougher edge, while a 60–80 tooth blade gives a smooth, splinter-free finish at a slightly slower feed rate. For a dedicated miter station cutting trim and general dimensional lumber, an 80-tooth crosscut blade or a combo blade covers most jobs without swapping back and forth.
Best DeWalt-Compatible Replacement Blade Pick
DEWALT DW3128P5 12″ Miter Saw Blade Combo Pack (80T + 32T)
One combo pack gives you a fast 32-tooth blade for rough dimensioning and an 80-tooth blade for splinter-free trim cuts — no need to buy two separate blades.
- Best for: Owners who switch between framing lumber and finish trim on the same saw
- Why we picked it: Matches the 12″, 1″ arbor spec used on DWS779/DWS780 and covers both rough and fine cuts
- Main drawback: Two blades to store and swap — not a single do-everything blade
Compare more replacement blade options
 Option 1 DEWALT DW3128 80-Tooth Blade
|
 Option 2 DEWALT DW3232PT Precision Trim
|
 Option 3 Diablo D1280X 80-Tooth Blade
|
As an Amazon Associate we earn from qualifying purchases.
Why Your DeWalt Miter Saw Blade Slips or Comes Loose
If the blade wobbles or the bolt backs off after a few cuts, the cause is almost always at the washer contact points, not the bolt itself. Check these three things before assuming the saw is damaged:
- Painted blade surface: new blades are often painted where the washers clamp down. A smooth painted surface can let the washer slip slightly under vibration — lightly scuff that contact ring with 100-grit paper so the washer bites metal, not paint.
- Resin or dust between the washer and blade: even a thin film of buildup on the inner washer or arbor flange stops the blade from seating flat. Wipe both clean before every install.
- A worn or deformed washer: if the outer washer no longer sits flat, it can’t clamp evenly. Replace a bent or scored washer rather than reusing it.
If the bolt keeps backing off even with a clean, unpainted contact surface, a drop of blue (medium-strength) threadlocker on the bolt threads is a standard fix — it resists vibration without permanently locking the bolt, so you can still remove it clockwise next time.
📊 Miter saws accounted for roughly 7,640 emergency-room-treated injuries in a single year — about 15% of all stationary power saw injuries tracked. — Source: U.S. Consumer Product Safety Commission, Injuries Associated with Stationary Power Saws
Can You Put a Dado Blade in a DeWalt Miter Saw?
No — not a stacked dado blade set like you’d use on a table saw. DeWalt’s dado sets (such as the DW7670 and DW812DADO lines) are built for table and radial-arm saws, and a miter saw’s arbor, guard, and throat plate aren’t designed to clear a wide dado stack safely. If you need a dado-style groove from a miter saw, the standard workaround is a flip-down depth stop combined with repeated passes using a flat-top-grind (FTG) blade, which leaves a flatter groove bottom than a standard ATB blade. For an actual stacked dado cut, use a table saw instead.
Lost Your Arbor Wrench? Here’s What Still Works
If the factory wrench is missing, a 13mm or 15/16″ socket wrench fits most DeWalt arbor bolts and actually gives you more leverage on a stuck bolt. Slipping a short length of metal tubing over an Allen-style wrench works the same way for models that use a hex arbor bolt instead of a flat one. Either way, you still need the spindle lock engaged — without it, the blade just spins with the bolt no matter what tool you’re turning it with. A stuck bolt from resin or corrosion usually breaks free with a few drops of penetrating oil and a 10–15 minute wait, rather than more force.
Frequently Asked Questions
Which way do you turn the bolt to change a DeWalt miter saw blade?
Turn it clockwise to loosen and counterclockwise to tighten. DeWalt uses a reverse (left-hand) thread on the arbor bolt so the blade’s own rotation during cutting keeps it tight instead of loosening it.
What size blade does a DeWalt miter saw take?
Most compact DeWalt miter saws take a 10-inch blade, while full-size compound and sliding models like the DWS779, DWS780, DW716, and DW717 take a 12-inch blade with a 1-inch arbor hole. Check your specific model before buying a replacement.
Can I use any brand of blade on my DeWalt miter saw?
Yes, as long as the diameter and arbor hole match your saw’s specifications. Diablo, Freud, and other reputable carbide-tipped blades fit the same 12-inch, 1-inch-arbor pattern as DeWalt’s own blades.
Can you install a dado blade on a DeWalt miter saw?
No, not a stacked dado set. Miter saws aren’t built to clear a wide dado stack safely. Use a flip-down depth stop with a flat-top-grind blade for miter saw grooves, or switch to a table saw for an actual dado cut.
Why does my DeWalt miter saw blade keep coming loose?
Usually a smooth painted surface at the washer contact ring, resin buildup on the washer or arbor, or a worn outer washer. Scuff the paint off the contact ring, clean the arbor before every install, and replace a bent washer rather than reusing it.
How often should you replace a miter saw blade?
Replace or sharpen a carbide blade after roughly 50 to 100 hours of cutting, or sooner if you see burn marks, hear the motor bog down, or notice chipped or missing teeth — whichever comes first.
“Do not depress the spindle lock button while the motor is running or the blade is coasting to a stop. Doing so could cause damage to the saw.”
Conclusion
The whole job comes down to one detail most people get backwards: DeWalt’s arbor bolt loosens clockwise and tightens counterclockwise. Hold the spindle lock, respect that reverse thread, seat the new blade with the teeth pointing down and toward the rear, and you’re back to cutting in a few minutes — no stripped bolts, no guessing on model-specific screws.
