6 Best Cobalt Drill Bits For Drilling Stainless Steel Troughs That Farmers Trust
For tough stainless steel troughs, farmers rely on specific cobalt drill bits. We review 6 top picks known for their heat resistance and longevity.
There’s nothing more frustrating than trying to add a float valve or a drain plug to a stainless steel water trough with the wrong drill bit. You stand there, leaning on the drill, making a lot of noise and smoke but barely scratching the surface. The right tool turns a half-hour fight into a two-minute job, and when it comes to stainless, that tool is a cobalt drill bit.
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Why Cobalt is a Must for Stainless Troughs
Stainless steel is tough stuff, designed to resist corrosion and abuse from livestock. That toughness comes from alloys like chromium and nickel, which also make it incredibly difficult to drill. Standard high-speed steel (HSS) bits, the black ones you find in most general-purpose kits, will overheat almost instantly and become dull.
Cobalt bits solve this problem. They aren’t just coated; they are made from a steel alloy that has cobalt mixed right in, typically 5% (M35) or 8% (M42). This special blend allows the bit to withstand the extreme heat generated when cutting into stainless steel without losing its sharp edge. It’s not about being harder, but about staying hard when things get hot.
Think of it this way: using a standard bit on stainless is like trying to cut a frozen steak with a butter knife. You might eventually make a mark, but you’ll ruin the knife in the process. A cobalt bit is the steak knife—it’s designed for the job and will give you a clean, efficient cut without destroying itself.
DeWalt Pilot Point Cobalt: The Farm Workhorse
When you need a reliable bit that you can find at almost any hardware or farm supply store, DeWalt is the answer. Their Pilot Point Cobalt bits are a go-to for a reason. The key feature is the tip design, which prevents the bit from "walking" or skittering across the curved, slick surface of a trough.
This means you can start your hole exactly where you want it without needing a center punch. For a quick field repair or a modification out in the pasture, that convenience is invaluable. You get a clean start and a round hole, which is critical for getting a watertight seal on a bulkhead fitting or drain.
These bits offer a fantastic balance of performance and accessibility. They aren’t the most exotic or expensive option, but they are tough, reliable, and get the job done without fuss. They are the dependable pickup truck of the drill bit world.
Milwaukee Red Helix: For Tough, Repetitive Jobs
If you’re outfitting a new barn or have a dozen troughs to modify, you need a bit that can handle repetitive work without failing. Milwaukee’s Red Helix Cobalt bits are engineered for exactly this kind of high-stress use. Their standout feature is the variable helix flute design.
This special groove geometry acts like an auger, pulling metal shavings (chips) out of the hole more efficiently. Better chip evacuation means less heat buildup, and less heat means the cutting edge stays sharp longer. When you’re drilling hole after hole, this design significantly reduces the chances of the bit binding or breaking.
The tip is also designed for a fast, clean start, similar to the DeWalt. The real advantage here is longevity under pressure. For someone who sees drilling stainless as a regular part of their operation, investing in a set of Red Helix bits means fewer broken bits and less time wasted.
Bosch Cobalt M42 Bits: Precision Engineering
Bosch has a reputation for precision, and their cobalt bits are no exception. These are often made from M42 steel, which contains 8% cobalt, making them even more heat-resistant than the more common M35 (5%) bits. This translates to an exceptionally long cutting life, even in the hardest stainless.
Where these bits truly shine is in creating perfectly clean and accurate holes. If you’re installing a fitting that requires a precise diameter with no burrs for a perfect seal, the Bosch bits deliver. The meticulous manufacturing process ensures the cutting edges are incredibly sharp and the bit runs true, reducing vibration and chatter.
This level of quality comes at a slightly higher price, but it’s a worthy tradeoff for critical jobs. When the tolerance for error is low, like installing a threaded outlet on a milk tank or a sensitive water system, Bosch is the professional’s choice.
Irwin Turbomax: Fast Drilling and Long Life
Irwin’s Turbomax bits are built for speed and durability. The aggressive 135-degree split point tip is designed to bite into the metal immediately, requiring less pressure from you to start the hole. This is a huge benefit when you’re drilling in an awkward position, like reaching over the side of a large trough.
The heavy-duty, one-piece construction makes them highly resistant to breaking under the high torque needed for stainless steel. Like other premium bits, they also feature specialized flutes to clear chips and reduce heat, but Irwin’s focus is on combining a fast start with a rugged build.
These are an excellent all-around option for the farm shop. They are aggressive enough to make quick work of tough jobs but durable enough to last. If your priority is getting the hole drilled quickly and moving on to the next task, the Irwin Turbomax is a solid contender.
Drill America Cobalt Set: Best Value for the Shop
Sometimes, you just need a full set of decent bits without breaking the bank. Drill America specializes in providing quality cutting tools at an excellent price point, and their cobalt sets are a perfect example. They offer a huge range of sizes in sturdy metal indexes, ensuring you always have the right bit on hand.
While they may not have the highly engineered flute designs or proprietary tip geometries of the big brands, they are made from genuine M35 cobalt steel. They hold a sharp edge and can handle stainless steel effectively, especially if you follow good drilling practices with speed and lubrication.
This is the best choice for stocking the farm workshop. You get a complete, reliable set for the price of a few premium bits. They are the perfect solution for the farmer who needs versatility and quantity without demanding the absolute peak performance for every single hole.
Norseman Magnum Bits: The Pro-Grade Option
For those who believe in buying the best and only buying it once, Norseman bits are the answer. Made in the USA from high-grade M42 cobalt, these are the toughest bits on this list. They are designed for industrial use, which means they are more than capable of handling anything on the farm.
The "Super-Chipper" point is engineered for aggressive, clean cutting in the hardest metals. Everything about these bits, from the material to the grind quality, is focused on maximum performance and tool life. They will drill more holes in stainless steel before needing to be resharpened than almost any other bit on the market.
The tradeoff is cost and availability; you’ll likely have to order them from an industrial supplier. But if you are tired of breaking or dulling bits and are willing to invest in a tool that will last for years, Norseman is the undisputed pro-grade option.
Tips for Drilling Troughs Without Breaking Bits
Owning the best cobalt bit is only half the battle. Stainless steel is unforgiving, and poor technique will snap even a premium bit. The secret isn’t brute force; it’s using the right technique to manage heat and pressure.
First, slow down. High drill speeds are your enemy. They generate immense heat, which softens the bit’s cutting edge and work-hardens the stainless steel, making it even tougher to drill. You want to see chips coming off the bit, not smoke. A good rule of thumb is a speed slow enough that you can almost count the revolutions.
Second, use firm, steady pressure. Don’t try to force the bit through the metal. Let the sharpness of the bit do the work. The goal is to create a continuous chip. If you’re getting dust or tiny flakes, you’re either spinning too fast or not applying enough pressure, which just polishes the steel and dulls the bit.
Finally, lubrication is non-negotiable. It reduces friction, cools the bit, and helps clear chips. While proper cutting fluid is best, a thick oil like 30-weight motor oil or even gear oil will work in a pinch.
- Go Slow: Use the lowest speed setting on your drill.
- Use Lubricant: Apply cutting oil or a heavy motor oil directly to the drilling spot.
- Steady Pressure: Lean into the drill firmly but don’t force it.
- Peck Drilling: For thicker material, drill for a few seconds, pull the bit out to clear chips, add more oil, and repeat.
- Let It Cool: If the bit or the metal starts to smoke or discolor, stop and let everything cool down.
Drilling stainless steel doesn’t have to be a battle of wills. By choosing a quality cobalt bit and using the right technique, you can make clean, precise holes exactly where you need them. Investing in the right tool saves you time, money, and a whole lot of frustration.
