DEWALT Cobalt Alloy Steel Drill Bit Set with Pilot Point, 14-Piece (DWA1240)

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Not easy to find non-MIC M35 (5% Co) sets here unless you want things cheap. In fact, this might be the only set as of now. Just so we are clear, I am reviewing the "DEWALT Drill Bit Set, Pilot Point, Cobalt, 29-Piece (DWA1269)" Cobalt Steel– The cobalt content increases the strength of the bit and aids in the resistance to heat and friction, so it can be used for more stubborn materials. Only use cobalt bits for drilling holes in metal, as the bits are too powerful for wood and other materials. This 13-piece set from Amoolo comes in at a fraction of the price of other cobalt drill bit sets. This set is durable, with 5 percent cobalt steel alloy, though not as strong as M42 bits, which contain 8 percent alloy. Using a lubricant or cooling water can help extend the life of these bits. Their split-point tips prevent walking and make starting holes easier. Ranging in size from 1/16 inch to ¼ inch, these bits come in a plastic carrying case with labeled sizes.

After 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 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. To evaluate how well the bits responded to resharpening, we drilled another round of three test holes for each bit in the scrap steel. The MIC bits can scratch the MIG bits but hardness does not mean quality. The MIG bits feel sharper and seem more well-designed and well-finished. cobalt content prevents maintains a sharper cutting edge and delivers • 4x longer life, and also provides stability at high temperature when drilling tough materials For the first round of drilling evaluations, we selected the 1/16-inch, 3/16-inch, and ⅜-inch bits from each set. The test materials included scraps of .25 sheet aluminum, .133 cast-iron pipe, and .065 square tubular stainless steel. 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. 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.M42 cobalt drill bits, which have 8 percent cobalt, are the hardest drill bits available. Why Trust Bob Vila bits and smaller do not have the 3 flats, nor "Made in Germany" stamp (too small most likely), but do say "HSS-CO" on them where the larger bits do not specify the metal grade. Suitable for portable or stationary drilling of high alloy content steels and metals with a tensile strength up to 1100N/mm²

Drilling through steel, cast iron, and other metals produces tiny shards that can end up in skin or eyes, so make sure to wear protective gloves and safety glasses when working with cobalt drill bits.The Irwin M35 drill bits performed well before and after sharpening—in fact, the bit had barely dulled after the first three holes. With or without a center punch to premark the hole locations, these bits drilled smooth, clean holes. Also, the split point was easy to line up at the proper angle to sharpen on the grinder.

Machinists, mechanics, DIYers, and crafters value cobalt bits for their ability to drill hard materials and because they can be resharpened. We spent 12 hours testing these drill bit sets. First, we used a drill press to evaluate them for drilling ability in aluminum, cast iron, and stainless steel. Then we resharpened them before performing a second round of drilling tests. (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.)There aren’t many materials strong enough to put holes in hardened steel. For that kind of strength, the only answer is cobalt alloy drill bits. It takes a tough bit to drill through hard metals like steel and bronze, but drill bits like these from Stroton are up to the task. Stroton uses what it calls a three-step design with this drill bit. Borrowing from step-bit technology, the tip of the bit is composed of three separate steps that help drive the bit through hard metals. This 19-piece metric set features sizes ranging from 1 millimeter to 10 millimeters. The Stroton cobalt drill bits featured a round shank with a low-profile stepped split point. They performed smoothly with or without center-punch starter guides. Unlike the more exaggerated pilot-style stepped points found on the DeWalt and Milwaukee bits that we tested, this design only stepped up a total of about 0.5 millimeters above the shoulders of the bit point, despite having more steps.