Milwaukee Cobalt Drill Bit

Drilling through tough materials can be a daunting task, but having the right tool can make all the difference. Enter the Milwaukee Cobalt Drill Bit, model 48-89-2317. This drill bit is designed specifically for hard metal applications and promises durability and longevity. With its cobalt alloy construction, variable helix design, and 135° split point tip, it certainly has the specs to back up its claims. Here's my deep dive into how it performs in real-world conditions.

Construction and Design

The Milwaukee Cobalt Drill Bit is made of a cobalt alloy, which is known for its enhanced hardness and heat resistance compared to standard black oxide bits. This should theoretically translate to longer-lasting performance, especially when drilling through hard metals. The bit also features a quad-edge tip designed to minimize heat generation and improve drilling speed, a crucial feature when dealing with materials that can quickly dull lesser bits.

The 135° split point tip is another notable feature, as it helps to ensure accurate starts and reduces the risk of the bit "walking" across the material surface. This is especially useful for precision work where exact hole placement is critical. Additionally, the variable helix design, ranging from 35° to 15°, aids in efficient material extraction, which should help in maintaining a clean and smooth hole.

Performance

I put the Milwaukee Cobalt Drill Bit to the test on a variety of materials, including stainless steel, mild steel, and PVC. Starting with stainless steel, I was cautiously optimistic. Stainless steel is notoriously difficult to drill through, often causing bits to dull quickly or even break. To my surprise, the bit managed to drill through a 3mm stainless steel sheet with relative ease, maintaining a consistent performance throughout the process. The split point tip did an excellent job of preventing the bit from wandering, and the material extraction was smooth, leaving a clean hole.

Next, I moved on to mild steel. Here, the bit truly shined. Drilling through 1/4" thick steel was almost effortless. The quad-edge tip kept the heat generation to a minimum, and the bit maintained its sharpness even after multiple holes. I did notice, however, that using cutting fluid significantly improved the bit's performance and longevity. Without it, the bit started to show signs of wear after a few holes, but with cutting fluid, it continued to perform admirably.

When it came to softer materials like PVC and wood, the Milwaukee Cobalt Drill Bit was almost overkill. It cut through these materials like a hot knife through butter, leaving clean and precise holes. While this bit is clearly designed for harder materials, it's good to know that it can handle a range of applications with ease.

Durability and Edge Retention

One of the most critical aspects of any drill bit is its durability and edge retention. In this regard, the Milwaukee Cobalt Drill Bit is a mixed bag. On the one hand, it performed exceptionally well in short bursts and on specific tasks. However, I did notice that the bit started to dull after extended use on particularly tough materials like thick stainless steel and cast iron. This is somewhat expected, but it does mean that you may need to have a sharpener on hand or be prepared to replace the bit sooner than you might with higher-end options.

Usability

The bit's design includes a 3-flat shank, which helps to prevent slipping in the chuck. This is a small but significant feature that enhances usability, especially when working with high-torque drills. I found that the bit remained securely in place throughout all my tests, which added a layer of confidence and precision to my work.

The 4-1/2" length and 3-3/16" flute length provide a good balance of reach and stability, making it suitable for a variety of drilling tasks. The bit's overall craftsmanship is solid, and it feels robust in hand, which is always a good sign.

Value for Money

The Milwaukee Cobalt Drill Bit is priced higher than standard bits, but given its performance, this seems justified. It's clear that you're paying for a specialized tool designed to handle demanding tasks, and in that context, it delivers. However, if you're primarily working with softer materials or only occasionally need to drill through hard metals, you might find the cost harder to justify.

Final Thoughts

The Milwaukee Cobalt Drill Bit, model 48-89-2317, is a formidable tool for anyone who frequently works with hard metals. Its cobalt alloy construction, variable helix design, and 135° split point tip make it a reliable choice for precision drilling tasks. While it does show signs of wear after extended use on very tough materials, its overall performance is impressive.

Would I recommend this tool? Yes, but with some caveats. If you regularly drill through hard metals and need a bit that can handle the task without frequent replacements, the Milwaukee Cobalt Drill Bit is a worthy investment. However, if your needs are more varied and include a lot of softer materials, you might find more value in a different bit that's less specialized but still durable.

In summary, the Milwaukee Cobalt Drill Bit excels in its intended applications and offers a good balance of performance and durability, making it a valuable addition to any serious DIYer's or professional's toolkit.