Understand 18-volt cordless reciprocating saw features & functions.
Subject: Cordless Reciprocating Saws, Part 1
Topic: Features of cordless reciprocating saws
Objective: Understand 18-volt cordless reciprocating saw features & functions
Task: Compare DeWalt and Milwaukee 18-volt cordless reciprocating saws for vehicle rescue tasks
Reciprocating saws are rapidly gaining in popularity among fire and rescue teams worldwide. Their acceptance prompted me to begin a research project to explore the capabilities of the newest generation of reciprocating saws, the cordless models. Currently, cordless reciprocating saws are manufactured by Milwaukee Electric Tool Corp. of Brookfield, WI, and by DeWalt Industrial Tool Co. of Hampstead, MD.
Through this series of University Of Extrication columns, we will look at the features of the saws themselves, explore various battery power supplies that are available, and learn about proper saw blade selection and use. Later in our series, we’ll report on reciprocating saw endurance tests conducted during more than 18 months of real-world fire service testing. In the final installment, we’ll introduce the newest generation of cordless reciprocating saws, those operating on 24-volt power supplies.
We begin our series by comparing features of the two current brands of cordless reciprocating saws. Milwaukee manufactured the first reciprocating saw in 1952 and coined the popular term “Sawzall”, a registered trademark of the Milwaukee Electric Tool Corp. In this article, we’ll look at its newest cordless saw, the 18-volt Power-Plus Sawzall, model 6516-21. The other cordless saw we’ll study is the DeWalt 18-volt model DW938.
The saws are similar in many ways, though it isn’t the ways the saws are the same that interests fire rescue personnel - it’s their differences. As a result of our intensive evaluation process, we’ll present to you both the strengths and the weaknesses of each tool in areas that are vitally important to fire-rescue personnel.
Tool weights were each similar with the DeWALT weighing approximately seven pounds with a battery and the Milwaukee saw and battery weighing 8 1/2 pounds. The DeWalt is 17 inches in overall length while the Milwaukee is 18 inches.
Reciprocating saws get their name from the fact that during operation, the saw blade moves back and forth to cut the material. This distance, known as the saw’s stroke, measures 7/8 of an inch on the DeWalt and an inch with the Milwaukee. Essentially a saw’s stroke determines that portion of a blade that will be doing the most aggressive primary cutting.
Along with a saw’s stroke is another important measurement referred to as its strokes per minute (spm). The saw blade travels one complete cycle back and forth as it cuts through the material. The number of these complete cycles per minute is the saw’s spm. The DeWalt saw has a variable rate of 0-2,800 spm as controlled by the squeezing of the trigger. The Milwaukee unit’s trigger control allows for a 0-2,000 spm. A reciprocating saw with a variable speed trigger runs faster as the trigger is pressed more fully. Both tools feature a safety lock trigger to prevent accidental saw operation. As a safety feature, there are no provisions on either saw to lock the trigger in the ?on? or ?run? position.
The blade clamp holds the blade in the working end of the saw. Reversing a blade in the clamp of a reciprocating saw may be necessary for unique situations where there is very limited access for cutting. Although the blade is reversible in both saws tested, meaning it can be positioned with the teeth facing up or down, there are important differences in the method by which the saw blade is secured in each saw.
Both tools use a keyless chuck design, which is a real convenience for fire-rescue operations. The Milwaukee design, called the Quik-Lok Blade Clamp, is a barrel-shaped twist design located between the end of the saw and the saw’s shoe. As the barrel is rotated, it releases its grip on the saw blade. When the operator lets go, a spring return tightens the chuck into the blade in the saw.