Tips needed for drilling through hardened steel?

Discussion in 'Tools and Materials' started by pet73, 5 Jul 2009.

  1. pet73

    pet73

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    I need to drill a hole of a few mm through a piece of hardened steel being around 5mm thick. The workpiece is mounted on a wall, so I do not have the option of putting it under a stationary column drill.

    Searching the internet left me with the following advice: use a extra hard drill bit, such as a Cobalt enhanced steel bit, a cooling liquid (e.g. some oil) and drill with not too high rpm.

    Well, I tried this, and my experience was the following:
    - I used Cobalt drill bits, but with no effect.
    - Drill bit had quite some tendency to travel, but I managed to keep it steady focused on one point for minutes, but this didn't even scratch the surface.
    - I have the feeling that the reason the drilling didn't work, was that you need to have a very small hole or dimple to give the drill something to start on, and that is the problem: how do I make this little start 'pit'? Hardened steel seems totally unpenetrable.

    Am I doing something wrong here? All tips are welcome.

    Thanks and regards.
     
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  3. wotan

    wotan

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    It sounds like you have set yourself a task, what exactly is the item?
    Have you tried making a dimple with a centre punch?
    It's also very difficult to get the required drilling pressure when drilling horizontally.

    Wotan
     
  4. wilhelm

    wilhelm

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    ffs , youre not trying to drill the lock off Alistair Darlings piggybank, are you???

    We need that fiver to see off the IMF.
     
  5. ^neo^

    ^neo^

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    Get a decent masonry bit and run at a fairly slow speed with plenty of force and plenty of oil, but dont run the drill on hammer!
    Bosch do some multi purpose drills (got blue paint down the spiral) which are good....... used one the other day to drill a hardened 'easi out' from a cylinder head that someone had snapped!
     
  6. wotan

    wotan

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    You may be getting close to the truth, hardened steel cannot be removed from the wall? call the police. :LOL: :LOL:
     
  7. trazor

    trazor

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    Hardened steel can easily be drilled using a stellite drill.

    But you must be able to remove this plate from the wall, and drill it vertically in a pillar drill, lots of pressure no coolant, watch out for red hot chippings..... :eek:
     
  8. xerxes

    xerxes

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    I agree with trazor that you're unlikely to be able to drill this unless you can take it off the wall and put in in a drill press.

    That is, unless it's possible to anneal it by heating it in situ.

    The last time I had to drill hardened steel, I used a carbide-tipped tile drill when nothing else I had would go make an impression. It involved a lot of pressure and red hot metal swarf.
     
  9. gcol

    gcol

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  11. Hitachimad

    Hitachimad

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    What it it...?
    If its very hard you might not even get through it, if its only a bit hard, shouldn't pose much of a problem, can you get in a steady stance to push all your weight on the drill?
     
  12. wotan

    wotan

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    Probably a wall safe, trying to drill to get some nitro in to open it.:cool: :cool:
    Wotan
     
  13. pet73

    pet73

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    Thanks everyone for the tips. Some extra information that might help to focus any new tips:

    - A drill press is not possible as it is quite a small object without enough metal space around it to magnetically fix a press onto.
    - I could indeed try to push all my weight on the drill. So far not tried because I thought starting with a small drill would be best, and small drills are easily broken so I didn't dare to give my full weight.

    This weekend I will buy myself a centre punch with hardened steel tip and use that to make a good starting dimple (tried it with a steel nail first, but - of course - it had no effect).

    Can someone explain what is a stellite drill ? Sounds very specialistic.

    The tip about using a masonry bit sounds almost unbelievable. Have plenty of them, and will give it a try, but I it would surprise me seeing any effect on steel!
     
  14. r896neo

    r896neo

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    a steel nail won't work as it will bend before marking it deep enough, A single firm blow with a lump hammer on a centre punch should leave a nice mark.

    A stellite drill is a special bit for hardened steel. It works by generating a lot of heat which softens the metal but you need serious pressure to get it started and i very much doubt you could use one on a hand held tool.
     
  15. trazor

    trazor

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    You will not drill a "hardened" steel plate by hand, vertically or horizontally.
    You will not be able to generate sufficient force, to start heating the plate/drill bit up, which carbide or stellite drills require.
    Plus these drills literally produce red hot swarf...... :eek: I use a welders apron when using stellite drills.

    As xerxes says, can you not get a set of gas bottles, and anneal/soften the plate in situ?
     
  16. joe-90

    joe-90

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    Have you got an arc welder? Just apply it to the workpiece where you want the hole and you will anneal a very small area - then just drill it out. If it's a rough job you can blow a hole in the workpiece with the welding rod.
     
  17. pet73

    pet73

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    I do not have an arc welder or gas burner. I am not a professional metal worker, just a DIYer. I prefer to make a few serious attempts in solving this problem myself before I call in help from a professional. I don't mind buying some good special drills - they will always come in handy - but using serious welding equipment is beyond my capabilities.
     
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