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6/6/2007

Pro Circular Saws


Pro Circular Saws
5/1/1998

Choosing a Pro Saw
They turn piles of framing lumber and stacks of plywood into a finished structure. These saws will rip, bevel, and crosscut. Install the appropriate blade, and they can even tackle concrete, tile, or metal pipe. Then again, these saws are built to handle such jobs, unlike their consumer-grade counterparts. Professional saws come with more powerful motors, stronger gearboxes, better bearings, and a raft of options not typically found on lower-priced models.

Whether you’re buying your first circular saw or looking to replace one, it’s worth taking a close look at the models the pros use, particularly when you consider their combination of power, versatility, and durability.

The 7-1/4" Standard
Circular saws come in a variety of sizes, designated by their blade diameter. They range from 3-3/8" cordless trim saws to 16" or larger giants used in timber frame construction. By far the most common size is 7-1/4". Using a blade this diameter allows the saw to remain fairly compact, yet provides plenty of bite to power through 2x stock with the blade laid over at 45°.

Most manufacturers also offer smaller, easier-to-handle versions -- 5-1/2" to 6-1/2" -- that will still cut 2x material at 90°. Though not as powerful, these scaled-down models are typically the saws of choice among finish carpenters.

Worm-drive Power
Circular saws come in two basic “flavors” -- worm-drive and sidewinder -- based on the motor position and type of gearing.

Worm-drive saws have motors positioned parallel to the blade, and use a worm gear transmission to power the blade. These deep-meshing gears, such as those in the Skil HD77, produce a blade speed of about 4,400 rpm (compared to 5,800 rpm for helical-gear saws). However, this slower speed is more than offset by an increase in torque.

Using a similar transmission with hypoid gears, Makita claims its longer, spiral-cut gears mesh more smoothly and positively than conventional worm gears. Whatever the hypoid’s advantages, other manufacturers haven’t seen fit to give up the proven performance and durability of worm gear transmissions.

To further boost performance, a sealed oil reservoir gives the gears and bearings a continous bath of lubricant, reducing wear and dissipating heat. As a result, worm-drive saws can gang-cut plywood or framing lumber without bogging down or stripping out a gear.

I first experienced this raw power buzzing through sopping wet, pressure-treated deck lumber with a borrowed worm-drive. (My old saw had already died trying to cut this soggy stuff.) I also remember how my wrist and forearm ached after 10 hours of hoisting that beast into cutting position.

These saws typically weigh 15- to 18-lbs, making overhead cuts an impractical and often painful experience. But skilled framers use this weight to their advantage by propping up 2x material on edge, and making crosscuts vertically, letting gravity help pull the saw down through the board.

Because the motor configuration puts the handle further back, I also find a worm-drive saw extends my reach when cutting a sheet of plywood. That long rear handle, combined with having the blade on the left side, also makes it easier for right-handers like me to eyeball straight cuts.

Sidewinder Speed
The other main type of saw has the motor mounted perpendicular, or sideways, to the blade. Hence its nickname, sidewinder. Top-end models use spiral-cut helical gears to transfer the rotation of the motor’s shaft to the blade driveshaft. While lacking the worm-gear torque, these gears allow higher speeds that in turn produce smoother cuts.

Most sidewinders have the blade on the right, although Porter-Cable offers left-bladed versions of its framers saw. Despite the fact that having the blade on the right makes it hard for right handers to view the cut, I’m willing to overlook this shortcoming because the saw is easier on my arm -- sidewinders tip the scales in the 10- to 13-lb. range. And when I trim the end of a board, most of the saw’s baseplate (and weight) rests on the workpiece. However, this wide base -- the result of the sideways mounted motor -- can sometimes get in the way when you need to make a cut in a cramped location.

From a cost standpoint, you can generally expect to pay more for a worm-drive saw than a sidewinder. Worm-drive saws start at about $150 and go up to $200, while contractor-grade sidewinders sell for roughly $120-$180.

Note: For specialized, less demanding applications, a cordless circular saw might meet your needs.

Pivot Points
Regardless of the type, you should look for several things in a circular saw. You want one with a strong, flat base. Stamped steel base shoes are more prone to bending and flexing because they lack the reinforcing ribs found on cast aluminum or magnesium bases. Blade height and bevel adjustments should operate smoothly, but lock firmly.

The blade height adjustment you’ll find on most saws consists of a fixed pivot point on the front of the saw and an arc-shaped guide at the rear.

An exception are two rear pivoting models offered by DeWalt. To raise or lower the blade, you loosen the front handle knob and the saw pivots around a point at the rear of the base.

A third type of mount -- the drop foot -- doesn’t have a pivot point. Instead the saw rides on a vertical rail system. Milwaukee has used this for years on its 6375-20 saw and earlier models.

For standard cutting, any type will do, but I have a preference when making plunge cuts. I like the smooth control I get with either of the pivoting styles. The drop-foot style has a tendency to bind and grab -- something to avoid for this precise work.

All saws will tilt to 45° for bevel cuts and many will go all the way to 50°, which is useful for rafter cuts in roof framing. Of those, several have locks at 45° so you don’t accidentally slide past to 50°. A few will tilt 3° to 5° in the opposite direction -- a neat feature if you need to back-bevel a piece of trim before scribing it to a wall.

Other Considerations
Most high-end saws have a spindle lock, which makes changing blades a snap. The lock button should be easy to reach while holding the saw in one hand and loosening or tightening the arbor nut with your other hand. For added convenience, look for a model with on-board wrench storage in the handle, like the model shown above.

Some saws have levers that let you retract the blade guard. This feature keeps your hands away from the outside of the blade guard and increases your control during the cut.

I’d also recommend a saw with an electric blade brake. This stops the blade in a fraction of a second after you release the power switch — a particularly nice feature if you consider the blade is exposed when the blade guard retracts during a cut. Many manufacturers offer a brake-equipped version of most models for $10 to $20 more.

My next saw will also have softstart. This feature lets the motor slowly come up to speed, greatly reducing the wrist-wrenching torque generated by a powerful motor snapping to full speed when you pull the trigger switch.

One feature most buyers often overlook is the cord. I want a cord that remains pliable in cold weather, and that’s at least 8-ft. long to give me room to move around. Several companies offer optional plugs with twist-lock prongs. They lock together with mating twist-lock extension cords or outlets, so they won’t come loose when you tug on the cord.

Which to Choose?
So which saw is best? Both and neither. Professional framers have used both types for years, so it depends less on what you need it to do, and more on just plain personal preference.

A quick poll of Workbench staffers showed that most own both types (or would if we could). Then again, we’re all tool fanatics. But in trying to justify owning both saws, I heard some common threads of wisdom. If there’s a job that requires high torque — gang cutting treated lumber or sawing out concrete or masonry — we all reach for our worm-drive saw.

For trimming sheet goods or making cuts that require lifting the saw over waist high, we’ll grab the sidewinder. After that, it turned into a heated debate related to brand loyalty and ambidexterity.

Suffice it to say that for most home woodworkers, any of these pro saws will meet your needs and last a lifetime. If you can, visit a building center and handle several models to get a feel for how they fit your hands. Find one that feels good, buy a good blade for it, and you’re ready to rumble.

This article originally appeared in Workbench, Volume 54, Number 3 -- May/June 1998.

(c) 2002, August Home Publishing Company. All Rights Reserved.

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