A Stihl TS420 concrete cut off saw features a 14-inch blade. You may need to replace the saw's blade, which can be constructed of abrasive carbon, over time due to wear and tear. To replace the Stihl concrete cut off saw's blade, you'll only need a few basic tools. You also can use other types of blades, such as a diamond-tipped version, with this type of Stihl saw. Replace every type of blade in the same manner.
Set the Stihl saw on a flat work surface such as a truck's tailgate, the ground or a work bench. Turn the saw so that the drive belt cover faces you and locate the bore hole near the front tip of the guard. Slide a metal pin, which comes with the Stihl saw, or small nail, if the pin is missing into the hole and spin the blade until it fully locks the wheel into place.
Turn the Stihl saw around so that the hexagon bolt that secures the abrasive wheel to the spindle faces you for easy access. Attach a wrench to the hexagon nut snuggly to avoid stripping the nut. Turn the wrench clockwise to loosen the nut. Unthread the nut the remainder of the way by hand and set it to the side. Remove the washer and set it next to the nut.
Grab the bottom edge of the carbon blade and tilt it toward you to remove it from the spindle. Slide it down to manoeuvre it from under the upper guard.
Insert the new carbon blade in the same manner as you removed it and slip it over the spindle. Slide the washer over the spindle. Spin the washer until the spindle grooves slip into the washer; catche and lock into place. Confirm that the threads of the nut are clean of debris and dust, then thread the nut over the saw spindle in a counterclockwise direction until it's tight.
Attach the wrench to the hexagon nut and fully tighten it. Inspect the washer, nut and carbon blade to make sure they are all sitting flush together.
Always turn a power saw off before working on it. Avoid direct contact with a recently used saw blade, which may still be hot. Wear medium to heavy duty work gloves to protect your hands from burns. Wear a dust mask and safety glasses to reduce contact with carbon dust.