Milwaukee 4-1/2" / 5" Grinder

As someone who's always on the lookout for reliable and efficient tools, I was eager to test out the Milwaukee 4-1/2" / 5" Grinder (model 2780-21). This cordless grinder promises to match the performance of corded models while offering the convenience and flexibility of being battery-powered. After putting it through its paces, I found that it lives up to many of its claims, with some caveats that are worth noting.

Design and Build Quality

The first thing I noticed about this grinder is its solid build quality. It's clear that Milwaukee designed this tool to withstand the rigors of heavy-duty use. Weighing in at 5.8 lbs and measuring 15 inches in length, it's not the lightest grinder on the market, but it feels well-balanced in hand. The anti-vibration handle does a good job of reducing fatigue during extended use, which is a nice touch for those long grinding sessions.

One standout feature is the paddle switch with a built-in safety trigger. This design prevents accidental startups, which is a significant safety enhancement. The paddle switch itself is easy to engage and offers good control over the tool. However, there's no option to lock the grinder in the "ON" position, which some users might find limiting for certain tasks.

Performance

Performance is where this grinder truly shines. The brushless motor delivers an impressive speed of 8,500 RPM, making quick work of cutting, grinding, and sanding tasks. Whether I was cutting through mild steel or grinding down welds, the grinder handled everything I threw at it with ease.

One of the key benefits of this model is its Rapid Stop brake, which brings the wheel to a halt in under 3 seconds. This feature not only enhances safety but also improves workflow by allowing you to set the tool down quickly between tasks.

Battery Life and Compatibility

Battery life is a crucial factor for any cordless tool, and this grinder is no exception. It runs on Milwaukee's M18 battery system, which is known for its reliability and long runtime. I tested the grinder with a 6.0Ah battery, and it provided ample power for most tasks. However, it's worth noting that more intensive jobs, like heavy grinding or cutting through thick materials, can drain the battery fairly quickly.

For prolonged use, I would recommend pairing the grinder with an 8.0Ah High Output battery or larger. Smaller batteries, such as the 5.0Ah, may overheat under heavy loads and require frequent swapping, which can interrupt your workflow.

Tool-Free Adjustments

Another feature that enhances the usability of this grinder is the tool-free accessory changes and guard adjustments. The FIXTEC nut with its flip-up handle makes changing wheels a breeze, eliminating the need for a spanner wrench. The guard can also be adjusted without tools, allowing for quick configuration changes depending on the task at hand.

However, I did encounter a minor issue with the guard. It tends to rattle slightly, especially when using heavier accessories. While this doesn't affect performance, it can be a bit distracting.

Versatility and Usability

One of the selling points of this grinder is its ability to handle both 4-1/2" and 5" wheels. This versatility makes it suitable for a wide range of applications, from cutting and grinding to sanding and polishing. However, the tool only comes with a 6" guard, which means you'll need to purchase a 4-1/2" guard separately if you plan to use smaller wheels. This additional expense is a bit of a letdown, especially considering the tool's higher price point.

Despite this, the grinder's overall performance and ease of use make it a valuable addition to any toolkit. The ability to work without being tethered to a power outlet offers tremendous flexibility, particularly in job sites where power sources are limited or when working in tight spaces where cords can be a nuisance.

Durability and Warranty

Milwaukee stands behind its tools with a solid warranty, offering 5 years on the tool itself. This level of confidence is reassuring, especially for a tool that will likely see heavy use. In my experience, the grinder has held up well under various conditions, showing no signs of wear or performance degradation.

Final Thoughts

The Milwaukee 4-1/2" / 5" Grinder (model 2780-21) is a robust and efficient tool that delivers on its promise of corded performance in a cordless package. Its powerful motor, rapid stop brake, and tool-free adjustments make it a pleasure to use. While the battery life can be a limiting factor for more demanding tasks, this can be mitigated with the use of larger capacity batteries.

The main drawback is the additional cost of purchasing a 4-1/2" guard, which should ideally be included given the tool's versatility claim. Additionally, the minor issue with the rattling guard could be improved for a more seamless user experience.

Overall, I would highly recommend this grinder for anyone in need of a powerful, cordless solution for cutting, grinding, and more. Its performance, build quality, and ease of use make it a worthwhile investment for both professional and DIY users. The flexibility of the M18 battery system further enhances its appeal, ensuring you have the power you need when and where you need it.