Drilling torque and speed have an inverse relationship
The relationship between cordless drill torque and speed is not straightforward. As the speed of the drill increases, the torque decreases. This means that when drilling at high speeds, there is less torque available. On the other hand, an impact driver provides more power as the speed increases. This is one of the key differences between a drill and an impact driver.
When you adjust the speed of a cordless drill, you are essentially changing the gears and determining the intensity of each mode. In the case of a brushless drill, there are also electronic components at play.
Product managers have to make a decision regarding cordless drill torque and speed. These are the two main factors most people consider when comparing different models, and larger numbers tend to be more appealing. However, sometimes a lower number can actually be better. For example, the Milwaukee Gen 3 M18 Fuel drill may not have the highest speed, but it has enough power to handle high RPMs. The Milwaukee team intentionally set the RPM cap to allow for extra torque at high speeds, enabling the drill to drive larger bits efficiently.
How should I choose?
Choosing between torque and speed on a cordless drill is not an exact science, but there are some general guidelines to consider. Torque rating is a standardized test that measures the maximum torque a drill bit can produce when locked. While this is a good starting point, it doesn’t always reflect the actual performance of the drill.
Let’s consider three drills with the following specifications:
- Torque: 1100 in-lbs
- High speed: 2000 RPM
- Low speed: 550 RPM
- Torque: 1150 in-lbs
- High speed: 2100 RPM
- Low speed: 450 RPM
- Torque: 1050 in-lbs
- High speed: 1900 RPM
- Low speed: 600 RPM
All three drills have similar torque ranges. At a glance, you might think that Drill #2, with its higher high speed rating, drills the fastest. However, under light load, Drill #3 allows you to use larger drill bits without dropping to low speed. Drill #1 strikes a balance between torque and speed.
The same logic applies to low speeds. While Drill #2 has the lowest low speed, it may provide longer-lasting torque and drive larger bits more efficiently. Drill #3 may seem attractive with its higher low speed, but it will struggle with heavier bits.
Ultimately, the decision depends on your specific needs and the type of work you do.
Great theory, any real data?
Here’s a comparison of three drills and how they performed compared to their specifications. These drills were chosen because their measured soft torque values were similar to each other.
- Listed Torque: 841 in-lbs
- Measured Soft Torque: 618.8 in-lbs
- No-load high speed: 2014 RPM
- High Speed Drilling Results: 1906 RPM (95% efficiency)
- No-load low speed: 457 RPM
- Low Speed Drilling Results: 433 RPM (95% efficiency)
- Listed Torque: 1090 in-lbs
- Measured Soft Torque: 585.6 in-lbs
- High Speed No Load: 2147 RPM
- High Speed Drilling Results: 1646 RPM (77% efficiency)
- No-load low speed: 550 RPM
- Low Speed Drilling Results: 474 RPM (86% efficiency)
- Listed Torque: 1300 in-lbs
- Measured Soft Torque: 615.6 in-lbs
- No-load high speed: 2000 RPM
- High Speed Drilling Results: 1621 RPM (81% efficiency)
- No-load low speed: 547 RPM
- Low Speed Drilling Results: 437 RPM (80% efficiency)
The actual results don’t always align with the theoretical expectations. However, there is a clear conclusion to be drawn. The DeWalt drill has the slowest no-load speed but the highest measured torque in both high and low ranges, despite being rated for less torque than the other two. The DeWalt drill shows high efficiency under load, while the other drills start to slow down. This allows the DeWalt drill to handle larger bits more easily, even if it sacrifices some top-end speed.
Make the call
Looking at the data on a broader level, not all results are exceptional, and there are some unexplained discrepancies. It’s challenging to compare different drills with different motors, batteries, and electronics and determine which one is the best.
The key to choosing between cordless drill torque and speed is to consider the nature of your work. If you frequently drill larger holes, sacrificing some top speed for more consistent high-speed performance is a wise choice. On the other hand, if you primarily use smaller drill bits and need higher tip speed, then a drill with a higher top speed may be more suitable.
At the end of the day, choose a cordless drill that fits your needs, budget, and quality expectations. Look for a battery platform that offers all the tools you require.