Even though the Kett KSV-432 Vacuum Saw has been around for 20-plus years, few tradespeople have seen one. That's bound to change as homeowners become increasingly aware of the health hazards of construction dust – and as the EPA begins to enforce the RRP lead-safe work rules enacted last year. I recently had the opportunity to use a KSV-432 on a job remodeling occupied rooms. Here's what I found out.
Kett's saw consists of a small circular-saw device attached to the business end of a drill body. To collect dust, you connect a shop vacuum to a 1-1/4-inch port on the blade housing. If you hook the tool to a HEPA-filtered vacuum, the manufacturer says, you will collect virtually all of the dust.
The saw takes proprietary blades: toothed steel for cutting wood, plastic, and metal; and abrasive blades for Sheetrock, plaster, and fiberglass. The model I tested takes a 2-1/2-inch blade and has a maximum cutting depth of 5/8 inch in soft material like drywall and plaster. Cutting depth decreases in hard materials like aluminum and steel. Had I needed more capacity I would have gone with the KSV-434, which accepts up to a 3-1/2-inch blade capable of cutting 1-1/16 inches deep.
Using the Tool
I first used the saw to widen a closet opening for a set of built-ins. The work was done in a fully furnished living room. After connecting the tool to an older Festool vacuum, I made about 12 feet of cuts through plaster-coated blue board. Within the first couple of feet I realized that the two hours I'd spent covering the floor and erecting a dust wall were completely unnecessary.
The KSV-432 cut quickly, and no dust escaped into the room from around the blade – except for a small amount during the initial plunge. I found the Kett to be more maneuverable than a circular saw, faster than an oscillating tool, and cleaner than a recip saw. The stellar dust collection greatly reduced my cleanup time.
The blade is concealed behind a spring-loaded shoe (left), which pivots up when the blade is plunged. The depth-stop is on the back of the tool (right) and is held in place by a hex screw.
The blade is covered by a housing and plunges into the work by means of a retractable spring-loaded shoe. This makes for better dust collection but means you can't see the blade and must use a notch on the housing (like the one on a circular saw) as your guide. The foot plate's hinge pin sticks out on both sides, so guiding the tool with a straightedge is not an option. If you're careful, you can cut to within plus or minus 1/16 inch – good enough for semirough cuts where a slightly uneven line is not going to matter.
My favorite application for the vacuum saw is making inspection holes in drywall, a task I performed countless times as an employee in the service department of a high-end builder. The problem with inspection holes is that they must be made in a hurry in emergencies (if, say, there's a plumbing or roof leak) – and often in finished spaces. Cutting access holes with the Kett saw was fast and painless; the time I would have spent on dust protection could be spent solving the problem at hand instead.
The vacuum saw is also handy for general demolition. I used it to take down drywall by cutting a dust-free 2-foot-by-2-foot grid pattern and simply pulling the pieces off by hand. It was as fast as other methods and a whole lot cleaner.
The saw is able to cut up to 1/8-inch aluminum and 16-gauge steel. I tried it on light-gauge metal studs, but – given the 5/8-inch cutting depth – it was slow and awkward. Cutting flat sheet metal would be a different story, provided the cuts didn't have to be perfectly straight.
Kett Tool Co.
Weight: 7 pounds
Motor: 5 amps
Max depth-of-cut: 5/8 inch
Price for saw: $440
Price for toothed steel blades:
$72 per dozen
Price for carbide abrasive blades:
Although the KSV-432 works well, its features could use some improvement. Changing blades is tedious because the housing is small and there is no arbor stop, so you must use both an Allen wrench and an open-end wrench. A different Allen wrench is required to change the depth-of-cut. With so many wrenches and blades, it would be nice if the tool came in a carrying case.
Also, there's no good place to put your free hand. It would be helpful to have the option of attaching the kind of side handle used on a hammer drill.
The Bottom Line
Despite its scant features and limited cutting depth, I like this tool. It cuts drywall and plaster very well and the dust collection is outstanding – I'd feel quite comfortable using it in finished rooms with minimal dust protection. It isn't cheap, but for the right kind of contractor it will pay for itself in reduced cleanup labor.
Doug Mahoney is a carpenter and freelance writer in Harvard, Mass.