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

Product Information

Cobalt drill bits consist of steel with a small percentage of cobalt—the higher the percentage of cobalt, the more heat-resistant and durable the drill bits will be. The amount of cobalt in a drill bit varies. An M35-grade cobalt bit contains 5 percent cobalt, while an M42-grade cobalt bit contains 8 percent. The higher the grade, the more expensive the bit. Tip Point 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. While cobalt drill bits will hold up better against heat than other drill bits, they will need to be sharpened from time to time. Sharpen dull cobalt drill bits using a bench grinder. Q. Are cobalt or titanium drill bits better? 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 Amoolo cobalt drill bits performed as well as some of the top name brands in our tests but cost a fraction of the price. They drilled smooth, clean holes, and the 135-degree split point was easy to align with the bench grinder for sharpening. It bears mentioning, however, that the kit only includes smaller bit sizes in 1/16-inch increments, which makes it ideal for crafting and detailed drilling.

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. Use a quality drilling lubricant with a high flash point. We used 3-In-One Multi-Purpose Oil for our tests. Also, drill at a slower speed with moderate downward pressure to avoid damaging expensive bits. 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. How We Tested Cobalt Drill Bits

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Still wondering if cobalt bits are the best tool for the job? Read on for answers to the most common questions about cobalt drill bits. Q. Can cobalt drill bits be sharpened? 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. 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.

There are four types of cobalt drill bits, with each type serving a specific purpose. Understanding the right application for each bit type is essential. The kit includes #1, #4, and #9 step bits. The #1 bit drills from ⅛-inch to ½-inch holes, with step increments of 1/32 inch. The #4 bit makes holes 3/16 inch to ⅞ inch, in 1/16-inch increments. The #9 bit drills ⅞- to 1⅛-inch holes in 1/16-inch increments.

What materials are used for drill bits?

Don’t throw away dull drill bits. Instead, sharpen them with a grinder to restore their sharp edges. Only use cobalt bits for drilling holes in metal, as the bits are too powerful for wood and other materials. HSS (High-Speed Steel)– HSS can withstand higher temperatures without compromising the hardness of the bit and is able to cut faster with more accuracy and efficiency. 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. Tool Steel with Tungsten Carbide Tips– TCT provides a longer working life for the bit while allowing for a more stable and solid tip and enabling it to withstand more rigorous drilling applications.

Since the manufacturer recommends these bits for cordless drilling, we tested the Milwaukee step bits twice, first in the drill press and then in a handheld cordless drill. They drilled fast and clean as billed. Then we tested the step bit’s unique ability to enlarge existing holes—a task that is nearly impossible to do cleanly with conventional twist bits. We clamped an old steel electrical junction box to the workbench and used the #9 step bit in a cordless drill to widen the punch-out holes from ½ inch to ⅞ inch. The resulting hole was perfectly shaped, clean, and smooth, with no burs. Drill bits are cutting tools that are used to remove material in a piece to create a circular hole. Having the right size and the right type of bit is key in ensuring the highest standard of work and ensuring that you can drill with confidence and accuracy. Learn more in our drill bit sets guide.

What coatings are used to enhance drill bits?

The Bosch cobalt drill bits offer a unique combination of structural features and extra-hard M42 alloy that make them a pleasure to work with. To test this product, we used a cordless drill and a drill press to highlight the difference between precision drill press work and handheld drilling. The cordless drill mostly worked well, but its variable-speed trigger made it more difficult to maintain a slow, precise speed for drilling steel. 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.