Cobalt drill bits are widely used in both woodworking and metalworking. Due to the hardness of cobalt, it can be used to drill metal, hardwood, and many more hard and tough materials. Cobalt drill bits are two types according to the cobalt percentage. The higher percentage is 8%, and it is named M42, and the lower percentage is M35 which includes 5% of cobalt. Due to these different percentages, both have different physical properties, which help to drill hard material in high RPM and longer service life.
What Is M 35 Drill Bit?
As mentioned earlier, M35 is a type of Cobalt drill bit. It contains 5% Cobalt in addition to steel. This Cobalt drill bit is highly resistant to high heat. According to that, the melting point of M35 is 2723 oF.
This type of drill bit can use to drill a hole into any metal. As for the performance of the M35, we can surely say that the M35 drill bits are the best in the market. Specifically, it is designed to deal with heavy-duty drilling in tough materials like iron.
What Is M 42 Drill Bit?
M42 is a type of Cobalt drill bit. It contains 8% Cobalt in addition to steel. This Cobalt drill bit is also highly resistant to high heat. According to that, the melting point of M42 is 2853 oF.
As for the performance of the M42, we can surely say that the M42 drill bits are also the best in the market. Specifically, it is designed to deal with heavy-duty drilling in tough materials like iron. Mainly, the M42 will work a fantastic job of drilling a hole in the heaviest surface than the M35 drill bits. Both M35 and M42 cobalt drill bits are good for metal drilling.
Differences Between M35 Vs. M42 Drill Bits
M35 vs. M42 cobalt drill bits are different in their base material. M35 has 5% cobalt, and M42 has 8% cobalt. Hence the physical characteristics also vary, and it affects the drill bit performance. Due to the high percentage of cobalt, M42 is harder than M35. Below is the comparison table for both M35 and M42.
| Characteristics | M35 Drill Bit | M42 Drill Bit |
| Percentage of Cobalt | 5% | 8% |
| Melting Point (oF) | 2723 | 2853 |
| Resistant to heat | Resistant to heat but less than M42 drill bits. | Higher resistance to heat |
| Status of sharpening | Enough sharp to drill a hole in any metal. | Sharper than M35 drill bits. |
| Durability | Sharp Enough to drill a hole in any metal. | Less than M35 drill bits because of consisting of more percentage of Cobalt. |
| Cost | Little cheaper than the M42 | Expensive |
How to Identify Cobalt M35 or M42 Drill bits
The color of the new Cobalt drill bits is dull gold. There is no painting or plating involved; the color develops as a result of the drill bits being baked during manufacture. You can identify the cobalt drill bit by following this guide.
Because of this, they can be reasonably quickly sharpened using cutting fluid and still be strong and durable. Although during the sharpening, the gold color can fade. The tip angle is 135o.
What Is Better, M35 or M42 Drill Bit?
Cobalt drill bit designed for hard tasks. Therefore, when concerned about the hardness of those two types of drill bits, the M42 drill bit is better than the M35 drill bit. The hardness of the M42 is 68-70 HRC (Rockwell Hardness Scale) but the M35 drill bit takes the hardness in 65-67 HRC.
The added M35 Cobalt drill bits have the extra benefit of being utilized in a handheld drill without much concern for breakage. The higher the percentage of Cobalt in Cobalt drill bits, the more likely they are to break. Therefore, the durability of the M35 drill bit is higher than the durability of the M42 drill bit. Therefore, M42 Cobalt drill bits are better suited for use in a foot drill where the drilling direction is controlled better than in a hand drill.
In Conclusion
M35 and M42 are both cobalt drill bits. M35 includes 5% cobalt and M42 includes 8% cobalt. Due to the different cobalt mixing, both have different physical characteristics. Overall, M42 is stronger and has more thermal resistance than M35. Hence M42 is good for harder metals. Obviously, M42 is a bit expensive than M35.
