The Dewalt brand is known for both its durability and portability. Dewalt produces a complete line of reciprocating saws that are either powered by electric or a rechargeable battery pack. Reciprocating saw are used extensively in demolition work. The blades actually reciprocate, or oscillate, in an up-and- down manner. Because they're used in heavy work, your Dewalt's reciprocating saw blade takes a lot of punishment and should be changed out on a regular basis.
Unplug your Dewalt reciprocating saw if it is electric-powered. If it is battery operated, remove the battery pack.
Purchase the correct blades for your particular model of Dewalt reciprocating saw. Do this by matching your saw's model number to the models covered on the packaging of the replacement blades. It is important to use the correct size blade for your specific saw because misfit blades can be dangerous to work with and can get stuck inside your saw, potentially causing irreversible damage.
Set your Dewalt reciprocating saw flat on its side on a work bench. Hold it with one hand.
Place the Allen wrench into the hex nut at the base of the blade housing and turn it counter-clockwise to loosen it. Loosen the hex nut and remove it completely.
Pull the old blade free. If it seems stuck, spray some liquid-spray lubricant into the lock area and jimmy the blade back and forth a little. Pull the blade out with a pair of pliers, if it gives you difficulty.
Slip the new blade, with the blade facing up, into the blade housing.
Replace and tighten the hex nut with your Allen wrench to secure it down firmly.