As an apprentice carpenter in Canada, I walked into the local tool store to buy my first circular saw. I had a growing interest in timber framing and had just read a book by a timber framer named Tedd Benson. According to his book, there was no question about which saw to buy for cutting beams and I was determined to have it. That particular saw was an 8-1/4-inch Skil wormdrive, which I still use today.
Now, I work alongside the man who wrote that book, helping to run the building systems department at Bensonwood Homes in Walpole, N.H. We build the floors and enclosure systems for our timber frame homes. We use circular saws with blades from 4-1/2 inches to 16 inches in diameter, but we use 8-1/4-inch saws most often in our shop and on our jobsites around the world. They're indispensable for making cuts into big materials. We use them to cut tenons out of 8-by stock, rip through nominal 3-by in one pass, and muscle through 1-1/8-inch floor sheathing.
I look for an 8-1/4-inch circ saw to be light, accurate, and easy to adjust. It must be rugged and powerful, and able to cut sheet goods, solid-sawn framing, and engineered wood products smoothly. The saw also needs to rip, cross cut, plunge cut, and cut compound angles found in roof framing.
I tested the Milwaukee 6378 and Skil HD5860 wormdrives, and five sidewinders including the Bosch 1656, DeWalt DW384, Hitachi C8, Makita 5008NB, and Milwaukee 6405-6. I ran the saws through 2-by at 90 and 45 degrees to check adjustments, guard action and cut accuracy. I also looked for stiffness between the saw bodies and shoes. I tested the saws' power by sending them through a stack of 1/2-inch OSB. I also evaluated balance and feel to find out which saw I'd want on the jobsite all day.
Seeing the line. I like to watch the blade cut the line no matter what the bevel angle is, so I usually don't use the guides on the saw base leading edge. Since sidewinders and wormdrives have different cut views, I made a list of what saws offered the best line of sight. In the sidewinder category, the Hitachi and DeWalt offer the best cut views at both 90 and 45 degrees. The Milwaukee model offered the poorest line of sight. Of the wormdrives, the Skil model beat out the Milwaukee wormdrive on cut view quality.
Shoe. To make straight cuts with accurate angles, circ saws must have stiff, flat shoes with strong connections to the tool bodies. Milwaukee's sidewinder uses an aluminum shoe and one point of attachment. That leaves most of the shoe unsupported and produces unwanted movement.
DeWalt uses an aluminum plate with a two-point connection: a front slide with a large locking knob and a rear pivot. I found this arrangement rigid and very easy to use. It also keeps your hands low for better control while operating the saw.
The wormdrives and the Bosch sidewinder use front pivots, rear slides, and stamped steel shoes. I checked the steel shoes with a machinist's straight edge and found them to be up to 3/32-inch out of flat. That's a little more than I'd like to see. Hitachi has the same front pivot/rear slide arrangement, but it uses a cast metal shoe which proved to be the stiffest and flattest out of all the saws.
The DeWalt shoe was 1/8-inch out of parallel with the blade when the saw arrived. It has an adjustment that allows you to true it up; however, when I adjusted the shoe parallel to the blade the saw wouldn't bevel more than 15 degrees. This threw me off enough to ask for another saw, but the replacement had the same problem. Fortunately, this only posed a problem when I cut against a fence in the power test. Otherwise, we found the saw worked fine for most procedures, even with the shoe a bit out of line.
Bevel adjustment. Except for the Milwaukee sidewinder, all the saws we tested have similar bevel adjustments. Milwaukee uses a tongue-and-groove, semi-circular track arrangement with a locking lever, but it allowed the bevel angle to change when the saw was set at 45 degrees The other saws use front and rear pivots and locking levers or knobs. This dual pivot system works better and all the saws seem equally stiff.
All the saws tested can roll over to 45 degrees. The DeWalt model goes further to 50 degrees, and the Bosch and Skil can go to 60 degrees. This extra reach is very handy in roof cutting.
All of the sidewinders have 90- degree adjustable stops -- set screws that let you dial the saws directly in to 90 degrees. The wormdrives don't have this feature. If you're constantly changing from bevel to 90 de-grees, this feature is nice to have.
All of the saws have angle scales to determine the bevels on the saw blades. They're almost all laid out in 5-degree increments. The DeWalt saw has 1-degree divisions and an adjustable pointer, which makes for finer adjustments if you need them.
Depth-of-cut scales. The Milwaukee wormdrive and Makita sidewinder saws don't have a marked scale. The Milwaukee sidewinder comes with tick marks, but no numbers. The Bosch and Skil saws have scales laid out for common stock thicknesses. They're set up so the blade protrudes 1/4-inch deeper than the scale's stock size, putting the blade at the correct depth for a given cut.
The Hitachi and DeWalt scales read the actual cutting depth. The DeWalt also has an adjustable pointer on the depth scale so you can zero out the saw for small differences in blade diameters. I had never used a cut-depth scale before, but found it useful for kerfing out notches. DeWalt's adjustable pointer is especially good for this.
Blade change. Blade changing is about the same for all of the models. They have arbor locks which make blade changes easy. The Bosch and Skil saws have a feature that the companies call a Vari-Torque Clutch, which, according to the owners' manuals, "permits the blade shaft to turn when the blade encounters excessive resistance, reducing the saw's tendency to kickback." This feature requires the blade bolt to be properly tightened to keep the blade from slipping during normal cutting. This wasn't the case, however; I really had to over-tighten the capture bolt to keep the blade from slipping. I think that clutch design could use some work.
Electrical. Except for the Milwaukee model, all of the sidewinders we tested are double-insulated. Neither wormdrive is double-insulated. External brushes are a nice maintenance feature. All the saws have them except the Bosch tool, which makes you remove a cover to access them.
All the saws come with adequate-length cords, but I found the cord on the Milwaukee wormdrive to be excessively thick.
A nice safety feature on the DeWalt saw is an electric blade brake that stops the blade in about three seconds. That won't help much for a kickback, but it can help prevent other jobsite injuries and quiets the saw down considerably faster.
Balance and Ergonomics
A tool's feel is often a question of personal taste. I like a saw's handles to be far enough apart for control, large enough for big hands, and mounted as low as possible. That's why I like to work with wormdrives so much.
The wormdrive's handle arrangement gives me a stable platform in case of kickback. The sidewinders tend to have handles mounted higher on the saw; I personally don't like this feature.
DeWalt overcomes overhand positioning problem by using a rear pivot for depth and providing large handles. This, combined with its relatively light weight, makes for a very comfortable tool. Bosch's saw also has comfortable handles, but they're mounted higher. The Skil saw feels good in my hands, but it's a little heavy. The Makita and Hitachi tools have small handles, but the saws' light weight can be a relief at the end of a long day. I found the handles on both Milwaukee models a little on the chunky side.
Guards. Some of the guards gave me some trouble. The Makita guard seems to have excessive side motion and it got hung up on 45-degree cuts. The guard on the Milwaukee sidewinder wouldn't clear the base at full-depth, 45-degree bevel cuts. Bosch has a guard retractor mounted near the front handle, which allows the guard to retract with your hands safely on the handle. The return spring is so heavy, however, I had to let go of the saw to help the guard over the blade. The guards on the rest of the saws worked fine.
Power, Speed, and Vibration
To test for power, I pushed the saws to their limits. I stacked five sheets of 7/16-inch OSB on top of each other, put brand new identical blades on each saw, and used a fence to keep me on line. Then I ripped through the stack as fast as I could go without stopping the blades. I averaged each saw's time for three passes. I expected the 15-amp saws to outperform their 13-amp cousins, but that wasn't necessarily the case.
At 27 seconds, the 15-amp Bosch was the slowest. It was very hard to keep it against the fence and it vibrated excessively when pushed hard. The DeWalt and Makita saws turned in times of 24 and 25 seconds respectively, but also vibrated a lot. The wormdrives were not as impressive as I thought they'd be. The Milwaukee wormdrive finished at 23 seconds, while the Skil clocked a 25-second average. They were a little smoother than the others, but not quite what I'd hoped for.
The power title goes to the Milwaukee sidewinder. It turned in a very impressive 20-second average, sat right on line, and was almost vibration-free. Milwaukee's saw has an impressive power plant. The 13-amp Hitachi saw was the runner-up in the power battle. It ran a 22 second average, was very smooth and easy to hold on the line.
It was difficult to choose an overall winner from this test. I did a lot of soul-searching and didn't want to betray my old wormdrive. I'm still not willing to hang up my old Skil, but I think I can find room for two saws in my personal tool collection.
The Hitachi saw is my new favorite -- not for any one feature, but for its overall performance in this test. This saw isn't the most powerful in this bunch, it doesn't roll over to 60 degrees, and its handles are a little small for my taste. However, it's one of the lightest saws in the test, ran the second fastest time in the OSB stack, runs very smooth, and you can really see the line. Another bonus, it has the flattest, stiffest base and its overall quality is very high. I like this saw a lot.
The DeWalt saw was my second favorite because of its good cut view and blade brake. The Skil wormdrive came in third, followed by the Makita side-winder, then the Milwaukee wormdrive, Bosch sidewinder and Milwaukee sidewinder.
Paul Boa is a timber frame carpenter at Bensonwood Homes in Walpole, N.H.
Tools of the Trade has arranged with the companies in this test to donate their tools to Habitat for Humanity.
Thanks to Freud for providing the blades for this test.