As a production framer building large-scale projects, I could probably measure the amount of plywood subflooring and decking we install in terms of acres. And while most framers still use pneumatic nailers to fasten their subflooring, the argument for screwing and gluing plywood to joists, based on reduced callbacks for squeaky floors, is strong. So we were especially interested in testing the latest batch of autofeed screwguns to see if we could maintain our speed and increase our quality in a production setting.
Autofeed screwguns basically come in three flavors: small one-handed tools for drywall and backerboard applications, versatile crossover models that come with extensions so they can be used to install subflooring from a standing position, and dedicated standing-application subfloor and deck models.
Versatility is the key word, though. These tools can be used to screw just about anything to just about anything else, and the manufacturers make screws for just about everything. There are screws for fastening drywall and plywood to wood or steel; special screws for ACQ-treated wood and composite decking; zinc-plated, galvanized, and stainless steel screws for exterior applications; and finish-head screws for interior jobs–to name just a few. You can find a use for these tools in just about any phase of construction, from framing to tile prep and everything in between, so we decided to limit the scope of this test to tools that could be used in a standing position for installing subflooring and decking.
The autofeed screwguns we tested basically operate like lower-speed versions of drywall screwguns, except they have specially designed nose attachments that work with collated screws. The screws are pressed into a strip or coil that feeds into the nosepiece of the tool. As each screw is driven, the tool automatically advances the strip, placing the next screw into position for the drive bit.
This is not to say that you can't bend over and install subflooring with one of the smaller tools. In fact, a number of people I spoke to said they prefer to do just that. They felt that leaning down to place the screws was just as fast and far more accurate. Bending over does put you closer to the work, giving you a better line of sight, but if you're running acres of floor deck, I think your back will eventually convince you that an upright model really is the way to go.
The autofeed screwguns we tested are the Makita 6834, the Muro CH7390 and FDVL41, PAM Fastening's P13KUE Universal Extension System, the Senco DS300-AC and DS300-S2, and the Simpson Strong-Tie Quik Drive PROCCSM35K (the Makita 3,500-rpm motor option). We also tested one tool that is produced and sold by two companies under different model numbers, either as the Grabber 7526HXT SuperDrive or the Hitachi W6VB3SD SuperDrive.
The Grabber/Hitachi, Makita, Muro CH, PAM, Senco S2, and the Simpson Quik Drive are what I'd call "crossovers," compact tools that would be great for drywall or any one-handed, close-in application and can be easily transformed into admirable stand-up subflooring tools. The Grabber/Hitachi, PAM, Senco S2, and Simpson Quik Drive accomplish this by adding an extension between the motor unit and the autofeed mechanism. The Makita and Muro CH make the switch by adding an extension handle to the rear of the motor unit.
The Muro FD and Senco AC are what I think of as "dedicated" subflooring installation tools–tools used only with the handles attached. Both are serious production tools.
In the first phase of the test, I took the tools into our shop and ran hundreds of screws through each one to get a feel for each model. The good news is that they all operated effortlessly; I could happily run subflooring with any of them. However, when all the tools in the test group are this good, it makes it pretty hard to pick a winner.
When I finished my shop testing, I took the tools out to the field where they got a real workout. We used them on a big job installing 3/4-inch OSB subflooring over engineered joists. We also ran a fair amount of 2x6 redwood decking fastening into ACQ-treated-wood deck joists. We looked at ergonomics and ease of use, quality and performance, and how the tools shook out in terms of practical applications.
Once the guys had a chance to work with all of the tools, we compared notes and made our recommendations.
The length of the tools in the test group range from approximately 36 inches to 42 inches. If you're tall like I am, the longer autofeed screwguns will appeal to you. If not, then maybe a 36-inch tool is going to be just right for you. The important thing is to be able to work in an upright position and reduce fatigue and back strain.
The good news is that some of these tools can actually be adjusted to fit your height. The length of the Senco AC can be adjusted from 31-1/2 inches up to 41-1/2 inches.
Makita's tool has an adjustable-length extension that gives you about a 4-inch range; with extension handle in place, it starts at 36 inches and can be extended out to just under 40 inches. You adjust the shaft length on the Makita by turning a thumb screw, but then you need an Allen wrench to adjust the tension cable that operates the trigger. This was enough to discourage me from adjusting the length of the tool very often.
Both Muro models use length-adjustable extension handles. The FDVL41 extension adjusts the tool from 35 inches to 42 inches and the CH7390 goes from 36 inches to 43 inches. The Muro extension handles don't have triggers, so you have to bend down and lock the motor in the "On" position to operate and bend down again to turn it off.
The Grabber/Hitachi, PAM, Senco S2, and Simpson Quik Drive are all fixed-length tools. Their extension tube is between the motor unit and the autofeed attachment, which puts the weight of the motor in your hands and keeps the nose of the tool light and easy to maneuver. By placing an extension tube on the handle of the screwgun, the Makita and both Muro autofeed systems put all of the weight of the motor at the bottom of the tool. I found the Grabber/Hitachi, PAM, Senco S2, and Simpson Quik Drive much easier to handle than the Makita or Muro models.
Grips & Handles
The grip and handle configurations of these tools vary, too. The most common is the pistol grip drill with a second handle coming off the extension shaft. The Grabber/Hitachi, PAM, Senco S2, and Simpson Quik Drive all use this design. The angle of the shaft handle is adjustable on all of these models except the Senco S2; its side handle is fixed at 90 degrees to the pistol grip, which is where you'd probably want it anyway. The handle on the S2 can be installed on either side of the tool to accommodate right- or left-handed operators.
The Senco AC also uses a pistol-grip design, but to hold this heavy tool with both hands in a standing position you have to put your free hand on the end of the tool. I could make this work, but it felt a little awkward. After swinging it around to place a hundred or so screws, I found myself wishing it had a side handle like its little brother, the S2.
The Makita extension has a wide-grip D-handle set at 90 degrees to the shaft and a wraparound grip lower down the extension tube, which I found uncomfortable. My left arm began to tire after running this tool for only a short time.
The Muro FD uses an extension tube with a T-bar handle. This is a solidly built tool that uses a big 150-screw-capacity drum set behind the driver nose, and weighs more than 11 pounds without screws. You have to sort of walk around the drum as you move the tool along. It takes a little getting used to, but in return you get the added fastener capacity. With the T-bar handle, the big drum, and beefy tool weight, I couldn't help but feel a little like I was operating a floor buffer instead of a fastening tool. It's a big tool, and it's all business, punching screws through floor deck effortlessly.
The Muro CH uses the same T-bar handle as the FD, but instead of the large drum it has a 30-screw collated strip-feed. Its lighter weight and smaller size make the CH a lot easier to handle, but I didn't feel like I had as much control of the tool with the T-bar handle as I did with the pistol grip and side handle configuration of some of the other tools.
I preferred the pistol grip and side handle configuration to any other. The weight distribution and maneuverability of the Senco S2 made it one of the most comfortable in the group to work with, even though it doesn't have height adjustment or even the capability to swing the side handle around to a more comfortable angle.
Collated screws come in brand-specific rigid plastic 30-screw strips, flexible plastic 50-screw strips, or in large coils containing 150 screws. The flexible plastic "floppy tape" strips are all interchangeable between brands–a real plus.
The plastic strip loads are lightweight and easy to handle, but they run out of screws pretty quickly. The big coils allow you to keep working without having to stop and reload, but they add weight to the tool.
Typical prices for these manufacturers' collated screws run from $26.50 to $31 per thousand for a 2-inch subfloor screw. The interchangeability of the flexible strips makes them generally cheaper than the proprietary rigid strip and coil types.
The tools in the group that use 30-screw rigid strips are the Muro CH and Simpson Quik Drive, while the Muro FD was the only tool requiring coils. All the rest accept the universal 50-screw flexible plastic strips.
Removing a Fastener
All of the tools we tested have a reverse switch and many of them provide detailed instructions on how to back out an errant screw. Don't bother. The problem is that you have to remove the remaining screws from the tool, switch the motor to reverse, bend over, and (somehow) align the tiny little screw tip of the 3-foot-long autofeed screw system into the top of the screw, and then climb back up and carefully actuate the motor. If you don't get everything lined up just perfectly, you're out of luck. I tried a few times and finally just resolved to have a cordless drill/driver handy in case I had to back out any screws. In reality, if a screw wasn't too far into the deck, I'd just yank it out with my claw hammer.
When you're shopping for an autofeed system, don't spend too much time worrying about how well it runs in reverse. Chances are you'll never use it.
In the end, choosing the right tool for you comes down to personal choice. The tool we liked best may not be the one you're most comfortable with, so do what you can to test-drive any tool before you buy.
If you want a lightweight tool that can switch from drywall to subflooring and back again, consider one of the versatile crossover models–the Grabber/Hitachi SuperDrive, Muro CH7390, PAM P13KUE, Senco DS300-S2, or Simpson Quik Drive PROCCSM35K.
Though the Makita 6834 also allows you to switch between standup and one-handed applications, it seems like it is really designed for one-handed use, as evidenced by the fact that it is the only tool in the group that doesn't ship with an extension. While it performed well enough in our subfloor test, it can't shoot fasteners larger than 21/4 inches and therefore had to be excluded from our decking test.
If you need a dedicated heavy-duty production subflooring tool–one you'll always use standing up–then you'll want to check out the Senco DS300-AC or especially the Muro FDVL41, the real workhorse of the bunch.
Overall, my favorite was the Senco DS300-S2. It's a versatile, high-quality screwgun, small enough to use one-handed running wall sheathing, but with extension in place has the power to be a dependable standup subflooring tool. It feeds a full range of screw sizes, converts easily, felt great in my hands, and shot screws quickly and accurately. This is a tool that I could happily work with day-in and day-out.
–Michael Davis owns Framing Square, Inc. in Albuquerque, N.M., and is a contributing editor for Tools of the Trade.