DeWalt addresses all those issues with this set. When drilling metal, some of the biggest headaches are bits that break, spin in the chuck, and bounce over the metal’s surface. Read on to learn how they performed in testing and why we consider them to be some of the best cobalt drill bits around. Our Top PicksĪfter researching more than 40 cobalt drill bit sets, we spent hours testing the following bits on aluminum, cast iron, and stainless steel. With that in mind, we assigned awards for each product based more on its features rather than on specific metal uses. While the unique tips on the Milwaukee 15-piece cobalt drill bits proved especially effective at drilling in stainless steel, all of these drill bits would do well boring clean holes into a variety of metals. We tested with an eye out for the best drill bits that might work especially well for specific metals, such as which ones may be best for stainless steel or best for cast iron. To evaluate how well the bits responded to resharpening, we drilled another round of three test holes for each bit in the scrap steel. We held the cutting edge to the wheel for 5 seconds on each cutting edge, once on the coarse grinding wheel and once on the fine wheel, making sure to maintain the 135-degree original tip angle. We drilled three holes in each of the test materials with every drill bit and then noted penetration speed (aggressiveness), cleanliness of the hole edges, and any noticeable changes from the first to the last hole.Īfter drilling the first round of test holes (or after the second round for some harder drill bits), we sharpened the ⅜-inch bits with a bench grinder. We calibrated the drill press rpm to match the bit size and material based on this chart and used 3-In-One Multi-Purpose Oil as a drilling lubricant. (For most products, we used a drill press for each set of holes however, for two products, we used a drill press and a cordless drill, as noted above.)įor the first round of drilling evaluations, we selected the 1/16-inch, 3/16-inch, and ⅜-inch bits from each set. Then we resharpened them before performing a second round of drilling tests. First, we used a drill press to evaluate them for drilling ability in aluminum, cast iron, and stainless steel. We spent 12 hours testing these drill bit sets. Machinists, mechanics, DIYers, and crafters value cobalt bits for their ability to drill hard materials and because they can be resharpened.
The smallest bits can safely drill at about 3,000 rotations per minute (rpm), but larger bits should turn no faster than about 1,000 rpm. Also, drill at a slower speed with moderate downward pressure to avoid damaging expensive bits. We used 3-In-One Multi-Purpose Oil for our tests. Use a quality drilling lubricant with a high flash point. In addition, be aware that drilling into hard metal requires a special technique to ensure that the bit cuts into the metal smoothly without overheating. Before making a purchase, shoppers will want to make sure they’re buying the right drill bits for the job. Because cobalt alloy bits are more expensive than conventional metal drill bits, they aren’t economical options for drilling materials like wood or masonry. While these bits can cut a variety of materials, they are specifically designed to cut through hard metals such as stainless steel, cast iron, hard steel, and even titanium. Photo: Debbie Wolfe Before You Buy Cobalt Drill Bitsīefore deciding to purchase a set of cobalt drill bits for metal, shoppers will want to make sure they know what they’re getting.
#Milwaukee drill bits for stainless steel upgrade#
UPGRADE PICK: Drill America Cobalt Jobber Drill Bit Set.
BEST BANG FOR THE BUCK: Amoolo 13-Piece Cobalt Drill Bit Set.RUNNER-UP: Irwin 29-Piece Cobalt Alloy Steel M35 Drill Bit Set.BEST OVERALL: DeWalt Industrial Cobalt Alloy Steel Set.This guide will help you find the best cobalt drill bits for turning metal into Swiss cheese. Read on to find out more about our shopping considerations and testing process. We researched dozens of cobalt drill bit sets before testing the following picks. These powerful cobalt drill bits for cast iron, aluminum, and even stainless steel are made of a steel alloy of 5 percent to 8 percent cobalt.
For that kind of strength, the only answer is cobalt alloy drill bits. There aren’t many materials strong enough to put holes in hardened steel.
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