Drilling hardened stainless

Discussion in '2-Stroke Engines' started by zippinaround, Sep 14, 2016.

  1. zippinaround

    zippinaround Active Member

    Someone told me ages ago to sharpen a masonry bit and it would drill through hardened steel , yesterday I finally put it to the test after ruining 3 hss bits actually made for metal and can confirm it works a treat, even roughly sharpened with a grinding disc .
     

  2. butre

    butre Well-Known Member

    I've not had good luck with that. it's easy enough to just anneal it and then heat treat it again when you're done adding holes
     
  3. zippinaround

    zippinaround Active Member

    how does one go about doing that? i was really surprised it worked was just a cheapo masonry bit too.
     
  4. butre

    butre Well-Known Member

    anneal, drill, harden, temper

    to anneal heat it to a dull red and let it air cool or bury it in sand, to drill you use a drill, to harden heat it cherry red or until it doesn't attract a magnet and quench in oil or water depending on the alloy, and to temper heat it in the oven to a faint straw color. if done properly, it'll come out about 62-65 rhc, which is about as hard as a knife. for a softer hardness, you temper at a hotter temperature. tempering it to a blue color will land you about 55 rhc, which is about as hard as titanium can get
     
    zippinaround likes this.
  5. zippinaround

    zippinaround Active Member

    Nice bit of info bud cheers , seems like a lot more work than just sharpening a masonry bit though .
     
    FurryOnTheInside likes this.
  6. skyash

    skyash Active Member

    I make gear and sprockets and get stuff flame hardened ..from nice silver steel to brown red blue color when it comes back it will kill a band saw blade in a second really good drill bits go blunt in half that .so we do all the work to the sprockets /gears before thay gets flame hardened . carbine drill bits work on hard metal even to drill out a drill bit or tap.
     
  7. zippinaround

    zippinaround Active Member

    you have any lying around you can drill a hole in and a cheap masonry drill bit the one i used was 1.49€ as part of a set ultimate cheapo alternative
     
  8. curtisfox

    curtisfox Member

    Just to let you know, to drill with carbide you need to spin them fast 2,500 or better. Chips will fly white hot but works great, i use Milwalky bits seem to last longer..............Curt
    PS. to drill stainless you do just the opposite really slow, never tried carbide on it i always use good colbalt.
     
    Last edited: Sep 19, 2016
  9. butre

    butre Well-Known Member

    you need lots of speed to drill hardened steel with carbide and what I find ends up happening is the brazing holding the carbide tip to the drill shank ends up softening and slinging a piece of hot carbide across the room into whichever pile is most flammable. could just be the particular bits I tried, but with that experience I'm not about to go experiment with different brands to see which one doesn't nearly burn down my shop.

    it's easy enough to anneal and re-harden steel. it adds an extra 20 minutes to the job and I don't need to ruin my good masonry bits.
     
  10. zippinaround

    zippinaround Active Member

    [QUOTE="butre, post: 420453, member: 2246]you need lots of speed to drill hardened steel with carbide and what I find ends up happening is the brazing holding the carbide tip to the drill shank ends up softening and slinging a piece of hot carbide across the room into whichever pile is most flammable. could just be the particular bits I tried, but with that experience I'm not about to go experiment with different brands to see which one doesn't nearly burn down my shop.

    it's easy enough to anneal and re-harden steel. it adds an extra 20 minutes to the job and I don't need to ruin my good masonry bits.[/QUOTE]
    Haha excellent reply , If I had a gas torch or anything to heat it I would definitely try it , but I'll add I drilled very slow about 1500rpm @ a guess maybe 3000 at most and was squirting it with 2 stroke oil
     
  11. Frankenstein

    Frankenstein Active Member

    That's all that matters sometimes. You people make me sick!
     
  12. FurryOnTheInside

    FurryOnTheInside Active Member

    I need to drill a couple of small (5mm I think) holes through a 4130 cromoly dropout (about 5mm thick plate). I hope they're not meant to be threaded.
    (I also am not equipped to anneal and reharden the bike frame and I would like to keep the powder coat.)
    Should I use HSS, carbide or a sharpened masonry bit for drilling 4130 cro-mo?
     
  13. butre

    butre Well-Known Member

    a good quality HSS bit should work on cromoly
     
    FurryOnTheInside likes this.
  14. FurryOnTheInside

    FurryOnTheInside Active Member

    Thanks! :)
     
  15. Nate888

    Nate888 Member

    let's all pitch in on a 220K PSI aerospace water jet cutter & be sure we get the job done

    I wish, right?

    I like the idea of annealing & re hardening, but the only torch I have available has trouble heating significant components past dull red, so I won't try that soon or anything
     
  16. butre

    butre Well-Known Member

    you don't need a torch, a forge is easy enough to make. a coal fire and a fan with a few bricks to keep in the heat will get steel white hot pretty quick. cheaper than hitting it with the acetylene torch too, if less convenient. much better for melting down aluminum too if you want to start casting parts.
     
    zippinaround likes this.
  17. FurryOnTheInside

    FurryOnTheInside Active Member

    The YouTube vids I've watched about making your own "bushcraft" knife from an old file use a simple forge like that. It does look easy, as long as you have the space for it.
     
  18. butre

    butre Well-Known Member

    I have about 5 square feet dedicated to mine. it doesn't take much. if you've got your own dirt you've got space for it
     
  19. FurryOnTheInside

    FurryOnTheInside Active Member

    Yeah that's what I meant. Lol. Outside space. :)
     
Loading...