I searched and found these listed at the top of buyers guide rated as 9.8 out of 10. I needed a bit to drill through hardened steel, specifically cast iron. I was concerned since it had to be 5/16” through 7/8” of iron. Using ProTap Cutting Fluid #30004P (also purchased from Amazon), I was able to easily drill 5 holes quickly without dulling the bit. I have a sharpener for drill bits just in case, but was not necessary yet.
I highly recommend these bits. Today, I used them again through stainless steel. Again, holes were drilled with little effort.
My only recommendations are to use a drill press, but can be done with a steady hand, and use lower rpm’s.
I hope this helps someone out.
| Material | Stainless Steel, Cobalt |
|---|---|
| Finish Type | Titanium |
| Shank Type | Straight |
| Cutting Angle String | 135 Degrees |
| Brand | BOSCH |
| Item dimensions L x W x H | 0.3 x 1.8 x 5.9 inches |
| Tool Flute Type | Spiral |
| Minimum Bore Diameter | 0.75 Inches |
| Surface Recommendation | Metal |
| Manufacturer | BOSCH |
| Part Number | CO2143B |
| Item Weight | 0.634 ounces |
| Product Dimensions | 0.3 x 1.8 x 5.9 inches |
| Country of Origin | China |
| Item model number | CO2143B |
| Size | 1/4 In. X 4 In. |
| Finish | Titanium |
| Item Package Quantity | 1 |
| Measurement System | Inch |
| Included Components | (1) 1/4 In. X 4 In. Cobalt M42 Drill Bit |
| Batteries Required? | No |
| Warranty Description | Product Defects Only |
