Test Results in Wood
The nail-embedded test boards worked as I had hoped: They wiped out the blades after an average of 60 cuts each while effectively highlighting the longest-lasting and fastest-cutting models.
To put the rigors of test cutting in perspective, the first-place model made 204 cuts, cutting through 187 feet of 2x6, 153 feet of OSB, 60 feet of drywall, and 2,448 nails.
Keep in mind that this test was designed to wear out blades – you will probably never encounter 12 nails in a single cut, so I would expect blades to last much longer under normal use.
Snagged nails. I was surprised by the amount of damage caused by the single row of 8d sinkers in the test plank. You'd think 16d commons would be tougher to cut – but the 8d nail snagged in the blades' gullets and sheared off the adjacent teeth. As soon as one tooth was gone, its neighbors tended to fall like dominos. The 16d sinkers found their way into some of the larger gullets, but the 8d nails seemed to get there first.
A few fresh teeth. Another surprise was how drastic an improvement a few fresh teeth can make. The hand-held saw's foot prevented me from using the first 1/4 inch of teeth out from the tang, but those teeth were in use in the rig saw. The blade could be smoking and sparking during freehand cuts but still cut fast in the rig.
This suggests that you can get immensely more life out of your blades if your saw has an adjustable shoe and you make use of it.
Orbital action. I performed all test cuts in the nonorbital setting, because while every saw can make lineal cuts, only some have orbital. When the main tests were complete, I performed limited testing in orbital mode, and the blade cut noticeably faster and made twice the number of cuts it made in linear mode. I had assumed the blade would wear more quickly cutting metal at this setting, but it didn't. The reason, a tool-company engineer explained to me, is that inline action drags the teeth over the nails on every return stroke, whereas in orbital mode, the teeth lift off the surface on the return stroke. That lack of friction on the return stroke more than makes up for the deeper biting action of the cutting stroke.
Cutting the Shingle Sandwich
For the roofing planks, I timed cuts 1 and 2, 11 and 12, and 21 and 22. In between, I made hand-held cuts. At cut number 22 I stopped cutting with the bimetal blades, because the teeth in the middle were completely worn away. The only reason they could still cut was that some of the outboard teeth never hit the shingles, so they still cut the OSB. The toothless part of the blade literally melted through the shingles.
The carbide-tipped blades held up better, so I continued with them until cut number 122. At that point I stopped; the blades were cutting more slowly but showed no signs of wearing out soon. Eventually, the carbide tips would have worn away – by my estimate, after two to three times the number of cuts already made.
This test really demonstrated the durability of carbide blades over bimetal blades in abrasive materials. If I had plunge-cut into an actual roof, the bimetal blades would have worn more evenly, and the outboard teeth would have dulled and slowed or stopped in the OSB. I chose not to show the cutting time of bimetal blades in roofing, because no tradesman in his right mind would continue to use a blade that looked as bad as mine did at 22 cuts.
The author tested for resistance to abrasion by sawing through shingles sandwiched between pieces of OSB (top). As was typical of the bimetal blades tested, the teeth at the center of this model (shown above after 22 cuts) were completely worn away. Only the carbide-tooth blades survived for long in shingles.
Carbide Tooth Models
I tested two carbide tooth models, a Lenox 6563RCT and a Diablo Demo Demon DS0606CW.
The Lenox blade is not intended for use in nail-embedded wood, and sure enough, it failed that test, quickly losing most of its teeth when it hit fasteners. But it did amazingly well in the shingle sandwich, cutting and cutting with hardly any loss of speed. When I quit at cut number 122 the blade was still going strong. It was designed to cut abrasive materials and does very well as long as the teeth don't experience any shock load.
The Diablo Demo Demon, by contrast, is intended for use in nail-embedded wood. It slowed noticeably as it dulled, but nails couldn't hurt it. I called it quits when it reached 150 cuts and a 45-second cut time – even though the blade had all its teeth and plenty of life left in it.
The Demo Demon performed admirably in the shingle sandwich but was much slower than the Lenox. That said, if I were cutting into an actual roof I would go with the Demo Demon, because its teeth won't chip or break off if they hit nails.
The Milwaukee blade features a unique tooth shape designed to prevent sudden shock loads that can break off teeth or stall even the mightiest saw. A tiny gullet and a depth-restricting "ramp" behind each tooth limits the bite made with each stroke. The gullet is small enough to prevent a nail from being hooked by a tooth – which proved to be the main cause of tooth fracture during the test. Even a skinny 8d sinker wouldn't fit in the Milwaukee's gullet.
Coated teeth. Another standout feature on a standout blade is the titanium nitride (TiN) coating on the teeth of the Lenox Gold blade. This thin ceramic film helped make this blade the best performer in the nail-embedded wood test. It even outperformed the carbide-tooth models.
Plunge-cutting teeth. Also worthy of note are the special plunge-cutting teeth at the ends of the DeWalt and Milwaukee blades – and, to a lesser extent, those of the Freud and Lenox bimetal blades. Greater clearance behind these pronounced teeth allows their tips to contact the wood at an angle optimized for plunge-cutting.
Both of these blades are Demo Demons; the lower one has made 126 cuts through nail-embedded wood. Although the carbide tips have been dulled, they remain intact and can still cut – though at a slower rate than when sharp.
Lenox's carbide-toothed blade may not cut nails, but it's great in abrasive material. The blade at the bottom was still going strong after making 122 cuts through shingles and OSB. The tips were worn but not damaged.
As long as there are no nails to chip or break its teeth, the Lenox cuts shingles and OSB faster than the Demo Demon. For material containing nails, though, the Demo Demon is the better choice because it can take the shock of hitting nails without chipping or losing teeth.
Despite the complexity of this test, I found some simple answers: Of the bimetal blades, the Lenox Gold is the fastest and longest lasting, followed closely by the standard Lenox blade. Third place goes to the Milwaukee Ax, which was well ahead of the rest of the blades.
Because of the speed and longevity of the top bimetal blades, I would not recommend carbide-tooth blades for nail-embedded wood – but for cutting more than a few feet in highly abrasive materials like asphalt shingles, carbide is the way to go. For sawing abrasive material that is free of fasteners, nothing outruns the Lenox carbide. Due to the fragility of the Lenox's teeth, however, I would recommend the slower but far tougher Diablo Demo Demon carbide for cutting abrasive material that might contain hidden nails.
Michael Springer is the former executive editor of Tools of the Trade.
Thanks to Grip-Rite for providing the nails used in this test.
Demo Blades Tested