Reddit reviews Hymnorq 1/16 Inch to 1/4 Inch 13PC M35 Cobalt Steel Jobber Twist Drill Bits Set,135 Degree Pilot Split Point, Metal Index Case, Extremely Heat Resistant, for Stainless Steel and Cast Iron
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COBALT STEEL - Manufactured from M35 cobalt steel, with molybdenum and cobalt added to create a hardened heat-resistant alloy, measuring Rockwell hardness up to 67, for much faster cutting and extra longer life span, with up to twelve times compared with an average HSS drill bit.SELF CENTERING - The 135°quick-cut pilot split points are self-centering and can penetrate quickly with less pressure. The bits will not "walk" or "wander". Straight shank allows for firmly holding and accurate centering, fit for standard drill chucks and regular round collet chucks.13PC FRACTIONAL INCH BITS - The set includes 13pcs of M35 cobalt steel twist drill bits: 1/16", 5/64, 3/32", 7/64", 1/8", 9/64", 5/32", 11/64", 3/16", 13/64", 7/32", 15/64", 1/4", well orgnized in a tough metal index case for easy storage. Manufactured to German DIN338 standard.FOR METALWORKING - Particularly successful in cutting through hard metals(hardness less than HRC38°) such as stainless steel and cast iron, although they can be used for softer materials like copper and aluminium, too. Not for hardened steel / high carbon steel. Try to adjust the RPM when it fails to penetrate.DOWNLOADABLE USER GUIDE - We've summed up some tips of drilling metals, including a RPM chart for several common metals, based on our reviews and some articles on the internet. In most cases, our customers would get a much better result with these tips. Welcome to download.
I used M35 grade cobalt steel. https://www.amazon.com/gp/product/B07MZZS2Y5 and https://www.amazon.com/gp/product/B07PTZ4XFW . I don't know anything about drilling metal, so maybe carbide would have been better.
For the drill press, I used https://www.harborfreight.com/10-in-12-Speed-Bench-Drill-Press-63471.html , which is a 10 inch .6 horse power drill press that goes down to 300 RPM. It was still underpowered at 300 RPM, so it got stuck sometimes. I worked around that.
For each cone I started at either 3/32 or 7/64 (I don't remember) and worked my way up, sometimes skipping one or two of the smaller drill bits.
I would recommend picking up a cone holder. I clamped the cone between two pieces of oak, which sort of worked. A correctly sized cone holder would have made it easier, though.