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I am trying to drill a 3mm cross hole through the head of a 18-8 stainless steel hex head screw . I am using a hand drill with a 3mm drill bit made of Titanium-Nitride (TiN) Coated High-Speed Steel.

Despite my efforts, I'm not able to make more than a dent in the screw head. The dent is shallow enough that the drill bit doesn't even stay put; it tends to slide side to side. I am surprised because the drill bit is advertised to be suitable for stainless steel.

I've tried drilling at different speeds and with varied pressure. I kept the contact point lubricated. Here's the photo of the result so far.

photo of screw head after my handiwork

Item specs:

Would you please advise me on how I can proceed? Is drilling a cross hole through a screw a fool's errand? What's the best tool for the job? Can it be done with a hand drill or Dremel?

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I'm afraid that you're going to have to use a drill press, and even that's going to be hard. If you've ever watched hex head bolts being made, there's lots of high-pressure compression used to form the bolt head, which creates a denser metal, which is hard to drill through.

Instead of buying a drill press (which i assume you don't have because you would have used it already) you may want to consider going back to the vendor where you got the drill bit and order a hex head bolt that is made for safety wire (common in the aviation industry). The hole you are attempting is already complete. If it is not quite big enough, it's much easier to enlarge an already-existing hole buy using incrementally larger drill bits.

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  • I found this: drilledheadbolts.com/t/… and shows a representative 18-8 bolt, although the price in the picture is US$99.00 !
    – fred_dot_u
    Nov 7, 2022 at 9:43
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    What is the reason for needing the hole? Perhaps there is another method to achieve the goal that does not require the hole to be drilled.
    – RMDman
    Nov 7, 2022 at 11:34

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