As a union laborer on the trans-Alaska pipeline project, I once had to cut truckloads of rigid foam insulation with a table saw. Clouds of noxious, statically charged dust billowed from the saw, some of which inevitably ended up in my lungs. I could have reversed the saw blade to reduce the dust, but that would have produced more fumes. Cutting with a utility knife would have been too slow and tedious.
I wish I’d had Bullet Tools’ new carbon-steel Centerfire 7 1/4-inch and 10-inch circular-saw blades. They have a knife edge instead of saw teeth and are designed to make swift, factory-smooth cuts in foam panels and insulating concrete forms while eliminating 95% of the dust.
I just made a series of test cuts with both blades through 1-inch-thick Owens Corning Foamular XPS foam and 2-inch foil-faced Rmax Thermasheath-3 polyiso foam. The blades worked exactly as advertised, creating virtually no XPS dust, and just a light sprinkling of polyiso dust. They seared some of the foam edges slightly, but didn’t overheat.
The 7 1/4-inch blade has a diamond knockout so it can fit wormdrive or sidewinder saws. I used a wormdrive because the manufacturer warns that sidewinders can bog down when cutting foam more than an inch thick. I installed the 10-inch blade in a portable table saw equipped with a riving knife, a blade guard, and anti-kickback pawls. I made most cuts freehand, as suggested by the manufacturer, but when I did use the fence, the foam would sometimes bind against it. To solve that, Bullet now includes with every 10-inch blade a “SpeedSpacer,” an adhesive-backed plastic strip that sticks to the side of the fence to prevent binding.
The 7 1/4-inch Centerfire blade costs $60, the 10-inch costs $90. According to the manufacturer, the blades will cut about 25,000 linear feet of 2-inch foam before they need to be resharpened. For a modest fee (plus shipping), Bullet Tools will handle the tuneups. —Bruce Greenlaw is a contributing editor to JLC.