how do i change the blade on this thing? the spindle lock button doesn't seem to engage to hold the blade still.

Diagnosis

The spindle lock failure on the DeWalt DCS570B is rarely a mechanical break and is almost always a synchronization issue between the locking pin and the arbor notch. The spindle lock mechanism consists of a spring-loaded pin that must drop precisely into a milled slot on the motor shaft. If the blade is off by even a few degrees, the pin will hit the solid shoulder of the shaft, making the button feel "mushy" or like it is pushing against a wall without actually locking the blade in place. This frustration is compounded by the fact that the DCS570B uses a high-torque brushless motor with a very tight tolerance. If you attempt to force the button while the blade is not perfectly aligned, you risk bending the internal actuator arm. To confirm the lock is working, you should feel a distinct, hard stop where the blade cannot be rotated manually in either direction once the button is fully depressed. If the blade still spins freely while the button is held, the pin is not seated in the notch.

How to Fix It

To successfully engage the lock and swap your blade, follow this exact sequence:

1. Disconnect the 20V Max battery immediately. Never attempt a blade change with a power source attached, as accidental trigger pulls can cause severe injury.
2. Pull back the lower blade guard (the retractable metal shield) and hold it in the open position.
3. Locate the spindle lock button on the top of the motor housing, just behind the blade.
4. Press and hold the spindle lock button firmly. While keeping the button depressed, slowly rotate the saw blade by hand. You are feeling for the "drop point."
5. Continue rotating the blade until you feel the pin suddenly snap into the arbor notch. The blade will stop abruptly and will no longer rotate.
6. Keep the lock button pressed firmly. Use a 1/2-inch (or 13mm) socket or wrench on the arbor bolt.
7. Turn the bolt counter-clockwise to loosen it. Note that DeWalt uses standard right-hand threads on this model, so "lefty-loosey" applies here.
8. Remove the bolt and the outer flange. Slide off the old blade.
9. Insert the new blade, ensuring the teeth are pointing upward and toward the front of the saw.
10. Replace the flange and tighten the bolt securely, but do not over-torque to the point of stripping the threads.

If That Didn't Work

• The "Manual Jam" Method: If the spindle lock button is completely unresponsive or feels stuck, you can use a "jamming" technique. Insert a sacrificial piece of scrap 2x4 wood into the base of the saw and apply light pressure against the teeth of the blade to create friction. This tension often holds the blade still enough for you to break the initial torque of the arbor bolt.
• Check for Debris: Sawdust can pack into the crevices around the spindle lock button, preventing it from traveling its full distance. Use a can of compressed air or an air compressor nozzle to blow out the motor housing gaps around the button to ensure the pin can drop fully into the notch.
• Lubrication: If the button is sticking, apply a tiny drop of dry silicone lubricant to the edge of the button. Avoid using WD-40 or heavy oils, as these attract sawdust and will eventually create a "sludge" that jams the mechanism permanently.
• Bolt Seizure: If the lock is engaging but the bolt won't move, the arbor bolt may be seized due to resin buildup from the wood. Apply a small amount of penetrating oil to the bolt head and let it sit for 10 minutes before attempting to loosen it again while the lock is engaged.

Heads Up

• Always check the blade diameter; the DCS570B is designed for 6-1/2 inch blades. Using an oversized blade can interfere with the guard and the base plate.
• Ensure the blade is seated perfectly flush against the inner flange. If the blade is tilted even slightly, the saw will vibrate violently and may cause the arbor bolt to back out during use.
• Check the condition of the arbor bolt threads every few blade changes. If you see flattening or "mushrooming" on the bolt head, replace the bolt immediately to avoid stripping it.
• Never use a hammer to "shock" the bolt loose; this can damage the motor bearings and ruin the precision of the saw's rotation.