I use circular saws every day and have never felt that cordless models had the power and runtime necessary for framing. A few years back, though, I bought a 36-volt cordless saw and found it to be a reasonable replacement for a corded saw in certain applications.
For this article we tested four higher-voltage saws – 36-volt models from Bosch, DeWalt, and Hilti, and a 28-volt model from Milwaukee. We used them while framing and siding a house and for building a deck. Later, we performed a test to see how many cuts each saw could make per charge.
WHY HIGHER VOLTAGE?
My experience with 18-volt saws has been that they are fine for cutting trim and the occasional stud or joist, but beyond that, they simply don't have the power I need. Just about anything I could cut with an 18-volt saw, I could cut faster with a higher-voltage tool.
The saws we tested are best for tasks that don't require a lot of repetitive cutting. We keep a corded saw at the cut station where we cut studs and window packages, and use a cordless saw for pickup framing and intermittent tasks like cutting and notching plates, installing drywall backing, cutting blocking in place, and building tub platforms and soffits. Cordless saws come in very handy on the roof; we regularly use them to trim rafter tails and cut roof sheathing. As long as you bring a charger and spare battery, you should be able to do this kind of work without having to wait for a battery to charge.
POWER AND RUNTIME
Designing a cordless saw that will work for framing is a balancing act – the tool needs to have a lot of power, but it also needs to have reasonable runtime and weight. In the years since these saws first came out, many have undergone battery upgrades – Bosch went from nicad to lithium ion (LI) and Milwaukee went from V-28 to M-28 LI batteries.
To gauge the relative runtime of these saws, I counted the number of cuts each could make through a 1-3/4-inch by 14-inch LVL on a single charge. To make things even, I equipped each saw with a new Freud Diablo blade.
All four saws powered right through the LVLs. Of the 36-volt models, the Hilti came in first, with an amazing 85 cuts, followed by the Bosch with 57.5 and the DeWalt with 39.5. As expected, the 28-volt Milwaukee couldn't match the runtime of the 36-volt tools, but at 35.5 cuts it was close to the DeWalt.
It's worth remembering that these were cuts through 14-inch LVL material, which is thicker and harder than framing lumber. If we had been cutting 2x12s, we no doubt would have gotten many more cuts per charge.
In this part of the country, we use worm-drive saws, so they're my standard of comparison. The saws in this review are sidewinders, but the Bosch, DeWalt, and Milwaukee models are configured like wormdrives in that their blades are on the left. The Hilti's blade is on the right. All the saws feel somewhat tail-heavy because of the battery in back. It's different from what I'm used to, but I can live with it if it means being able to work without a cord. The difference should be less noticeable to tradespeople who normally use sidewinders.
The Bosch and Milwaukee take 6-1/2-inch blades, and the DeWalt and Hilti take 7-1/4-inch blades. Bigger blades usually mean greater cutting capacity, but that's not true of every saw. The Hilti can cut through 2-by stock at a 50-degree bevel, and so can the Bosch – even though it has a smaller blade. The DeWalt and the Milwaukee can cut through 2-by stock at 45 degrees but not at 50 degrees.
None of these saws appear to be as rugged as corded models – the most obvious weaknesses being the plastic blade guards on the Bosch and DeWalt. The Hilti and Milwaukee have conventional metal guards. The baseplates on these saws don't feel as stiff as the baseplates on the better corded models.