Depth and bevel

It should be easy to accurately set the depth-of-cut and bevel angle. Large levers or knobs with a sturdy locking feel are preferable to smaller ones, and precise engraved markings in one-degree increments on the bevel quadrant help in dialing in the exact angle needed.

Cut-line marker

For fast and accurate cutting, the marks on the front of the saw base should be perfectly aligned with the actual blade kerf for both 90- and 45-degree bevel cuts. Since the saw's body-to-base connection cannot be adjusted, inaccuracies in these notches are best corrected with a little filing. For the greatest accuracy, mark the exact width of your blade in ink just behind the notch; that way, you can easily cut to either side of a marked cut line.

Blade visibility

It's not always possible to see the cut-line marker from all cutting positions, so you have to be able to see the blade. Because I tested mostly blade-left models, I found the blades to be well-exposed (during right-handed use) — but a few of the tools have top guards or guard-retraction levers that are low enough to obstruct the view of the cut when the saw is set to its maximum cutting depth.

PERFORMANCE TESTING

With cordless circ saws, it ultimately comes down to power and runtime. Every one of these tools can cut trim and sheet goods. They can cut dense framing materials, too — though in some cases you have to cut slowly to get through. When pushed hard in dense composite material, a few of the tools stalled so frequently they were hardly worth using. Only a handful proved capable of cutting everything on site without either slowing down or requiring a lot of babying.

As for runtime, batteries had better pack enough juice for at least half a day's work. And even then, the kits with only one battery will have to be charged while you're eating lunch. Don't expect to replace a corded saw at the cut station of a framing job with one of these saws — but with the best able to crosscut 68 sheets of OSB on a single charge, you may be surprised at how much a battery-powered saw can do.

To compare the performance of the 18-volt saws with that of more common job-site tools, I included in my power testing a new 15-amp corded circ saw (DeWalt DWE 575) and the 36-volt model (Bosch 1671) that won the last two tests in TOOLS OF THE TRADE.

The author checked the accuracy of the cut-line markers by cutting with the baseplate against a framing square (left) and then pulling the saw back to see if the cut-line marker aligned with the kerf. The cut-line marker on the saw in the center photo is off by almost half the width of the kerf, but the one on the saw at right is dead-on.

Power is even more important than runtime. No one wants to use a tool that struggles to do the job. To get a sense of the tools' relative power, I timed how long they took to do the same amount of work; the more powerful the tool, the less time it took. The main test involved cutting across 4 feet of industrial particleboard (chosen for its uniformity and high density). I began with ¾-inch material — and when that didn't challenge the saws, I created a 1 3/8-inch test blank by adding a layer of 5/8-inch particleboard.

For precise cut times I used a homemade timing device. It consisted of two micro-switches that I'd embedded 45 inches apart in a straightedge and wired to an electronic stopwatch. The stopwatch started when the saw base hit the first switch and stopped when it hit the second. The 45-inch spacing allowed me to measure cutting speed under load with the blade fully engaged, which eliminated variations caused by the blade entering or exiting the material.

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To ensure accurate timing during the main power test, the author built a crosscutting guide with embedded micro-switches at either end wired to an electronic stopwatch. The stopwatch started when the saw hit the first switch and stopped when it hit the second.

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I pushed the saws as fast as they could go without excessive straining or shuddering. If I went too fast, they stalled — the blade stopped with the motor engaged, or internal circuitry cut power to the motor to prevent it from burning out. Whatever the cause, it forced me to slow down. Some saws stalled so easily in the material, I could record only one or two uninterrupted times in a dozen tries. The best saws cut smoothly every time, slowing when pushed harder but never stalling (for power and runtime test results, see charts on page 30).

The last time I tested cordless circ saws, I timed how long it took to cut through homemade 2x12 LSL (a four-layer stack of 7/16-inch OSB 11¼ inches wide). I repeated that test with these saws to see how they compared with previous models. In the earlier test, some 18-volt saws could not make it through this material. Now even the weakest 18-volt models struggled through, and the strongest sailed through faster than the best 36-volt models.

Runtime

I tested runtime by counting the number of cuts it took to deplete each tool's batteries. I made the cuts across the 4-foot side of doubled-up 7/16-inch OSB, with each cut counting as 8 linear feet. To avoid overheating, I made them at a moderate pace in groups of 10 before resting the saw. All but the Ridgid and Porter-Cable were able to make that many cuts without overheating.

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Performance Test Results