Bob Vila has been America’s Handyman since 1979. As the host of beloved and groundbreaking TV series including “This Old House” and “Bob Vila’s Home Again,” he popularized and became synonymous with “do-it-yourself” home improvement. 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. 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. Read on to find out more about our shopping considerations and testing process. This guide will help you find the best cobalt drill bits for turning metal into Swiss cheese. 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.

Working with the Drill America M42 drill bit was almost an identical experience to working with the Irwin drill bit set, but this set is made of tougher metal and provides easier access to all of the bits at once. Both sets offer the same size assortment, the same round shank, and 135-degree split-point construction. Drill America’s bits remained noticeably sharper after the first three test holes, so we drilled a second set of three holes before sharpening. Sharpening took slightly longer, but the split point made it easy to align them with the grinder. Carbon Steel– This material provides a drill bit with better durability and hardness, therefore increasing the life of the bit. Carbon steel can withstand higher temperatures and is more suitable for harder 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.

What materials are used for drill bits?

Step drill bits offer the advantage of fast, clean precision drilling into thin metals without changing bits. Each of this set of three cobalt step drill bits is designed and engineered to drill up to 1,000 holes into 14-gauge steel. They feature a rapid strike tip for faster starting, elongated dual flutes to reduce heat buildup, and smaller step gradients for smoother drilling.

Twist– The most common type of drill bit and ideal for drilling wood, plastic, and metals. They are generally made from HSS and are suited to general household DIY tasks, as well as professional applications like maintenance and engineering. 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 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. The raised center point didn’t get in the way when we sharpened the edges of the bit point, but sharpening the center of the point was more challenging. However, we found that these durable bits, housed within their well-built hard plastic case, would make a great addition to a workshop.

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. 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 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. Counterbore. Counterbore drill bits create holes that allow the head of a fastener to sit below the material’s surface. Unlike countersink bits, which create an angled hole for fasteners with angled heads, counterbore drill bits create a larger hole at a shallower depth. A counterbored hole creates a flat ridge on which the head of the fastener can rest. 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.

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.) 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. 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

Common types of 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? 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.