Register now to get rid of these ads!

Drilling through hardened steel

Discussion in 'The Hokey Ass Message Board' started by 1oldtimer, Nov 18, 2011.

  1. Anyone have a good way to drill though hardened steel. I've tried hss drill bits and colbalt both with lots of cutting fluid and it just polishes the slight hole. I was thinking maybe carbide ???.
     
  2. Carbide is your best bet and go slow with the RPM's.
     
  3. Deuces
    Joined: Nov 3, 2009
    Posts: 23,753

    Deuces

    Ditto on the slow rpm's!!!
    A pilot drill wouldn't hurt also... ;)
     
  4. drifters cc
    Joined: Feb 16, 2010
    Posts: 178

    drifters cc
    Member

    You say hardened steel. That could mean alot of things so I'll make an educated guess and say Oh 65 sfpm (surface feet per minute). Multiply that by the constant 3.82and you get 248. Then divide The drill bit diameter into that.

    EX 228/.125= 1800rpm
    228/.250= 912rpm
    228/.312= 730rpm
    228/.437= 521rpm
    228/.500= 456rpm
    Stay away from carbibe unless your set up is very ridged, it is brittle and prone to crack/shatter in less than optimal conditions.
    Most any sharp bit with proper tip geometry will work with proper rpms/ridgity/and maybe cutting oil.
    Good luck
     

  5. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,657

    Rusty O'Toole
    Member

    Oxyacetylene torch and an tapered punch. Knew an old timer who built lots of things this way. He used a WW2 surplus machine gun barrel to make the holes round. Just drive it into the red hot hole with a big hammer.
     
  6. This was a reply to a similar question on an Engineeering board. Head his advice
    I work for Conicity Technologies and we put the edge prep on tools the way they are being used. On your drill we would put .003-.004 in the center and maybe .0015 to the corner leaving it sharp so there is no rubbinb. Both flutes will be exactly the same and it cuts around it's own center line making it cut straighter. We improve tool life and hole quality. Where the SFM is low we have small edge prep, where it is high SFM we put on larger edge prep. Were making the edge cut along the chip load. Visit www.conicity.com

    We can help,
    Steve Roberts
     
  7. Deuce Daddy Don
    Joined: Apr 27, 2008
    Posts: 5,544

    Deuce Daddy Don
    ALLIANCE MEMBER

    Acetylene torch & preheat well.
     
  8. kiwiandy
    Joined: Apr 19, 2005
    Posts: 419

    kiwiandy
    Member

    Solid carbide drill bits (often marketed as "rock drills") will work but as noted earlier are very brittle. They are no good for intermitant cutting and suited to drilling in a press or mill where both the work piece and the drill can be held ridgid.
     
  9. kiwiandy
    Joined: Apr 19, 2005
    Posts: 419

    kiwiandy
    Member

    I would love to see this done! Would work on non accurate through holes I guess? Only issue would be with changing the structure of the metal?
     
  10. Yeah, I reckon it won't "Hardened Steel" anymore
     
  11. tfee
    Joined: Oct 10, 2006
    Posts: 140

    tfee
    Member

    Carbide will do it but like they said above, hold the bit in a drill press and put the part in a secure vice. I wouldn't suggest breaking out the torches, after all, there is probably a good reason the part you are drilling is hardened. Better advice could be given if you described what you are drilling.
     
  12. If you can temper the stl to soften it then drill with cobalt or HS. In the old days done with car battery and cables, just get the area red hot and cool slowly.
    The truth about carbide is that it works best at high speeds. I use a die grinder with carbide to remove broken taps and even broken drills.
    You can also get carbide tipped drills for machining (not rocks) cheaper and move forgiving than solid carbide ones.
    J
     
  13. CDXXVII
    Joined: Nov 5, 2010
    Posts: 144

    CDXXVII
    Member
    from Vermont

    Hey, if it's a rare/irreplacable part you may want to take it to be EDM'ed.
    (Electo-Discharge Machining)
     
  14. How hard? What is the part? What size hole? "Rock Drill" is not going to work, you will need a proper carbide twist drill or perhaps a spade drill. And the part must be secure,as mentioned.
     
  15. It may just be case hardened in which case after the first .060-.120 it will cut much easier. It all depends on the rockwell hardness of the piece and what it is your doing to it.
     
  16. carcrazyjohn
    Joined: Apr 16, 2008
    Posts: 4,843

    carcrazyjohn
    Member
    from trevose pa

  17. HemiRambler
    Joined: Aug 26, 2005
    Posts: 4,208

    HemiRambler
    Member

    As my expert machinist buddy has told me numerous times "carbide loves speed"

    Don't be afraid to experiment a little with the RPM's.

    I was once stuck in the field working on some equipment where I broke a tap in some 3/4" plate. It was flush and despite my efforts was not budging. So what's a poor man's alternative in less than optimal conditions??

    An el-cheapo masonary bit. The bit wasn't pretty when I was done - but I managed to drill thru the tap and save the part. Desperate times call for desperate measures...
     
  18. jcmarz
    Joined: Jan 10, 2010
    Posts: 4,631

    jcmarz
    Member
    from Chino, Ca

    you can try starting with a small drill bit and work your up to the correct size.
     
  19. kiwiandy
    Joined: Apr 19, 2005
    Posts: 419

    kiwiandy
    Member

    Rock Drill is/was a trade name of the solid carbide drills I have used often in the past. Masonary drills (carbide tipped) are for drilling rocks but I have used them sharpened and used successfully for mobile applications/field work with hardened steel :)
     
  20. lucky ink
    Joined: Feb 18, 2011
    Posts: 358

    lucky ink
    Member

    speed man speed lol..I drill through 46 48 Rockwell H13 daily tapmatic and carbide drill just clamp and drill.I prefer collet over a drill chuck
     
  21. whoa....thanks for all the responses. It's a hood latch, the part that goes into the hole. I've heard is fairly common for the hood to pop open when driving on the 53-56 F100 (I guess that's why they make a tilt kit for the hood) and I was going to drill a 1/4" hole through the end and make a removable pin or stud for safety and security. Imagine my surprise when new HSS quality drill bit wouldn't cut at all and the cobalt made a small dent. The thing is about 1 1/2 thick and I'm using a drill press with a vice, I'll try mine at home with the lowest setting and some carbide bits.

    I've used a carbide tool made for tile in my dremel to get out a broken tap before.
     
    Last edited: Nov 19, 2011
  22. Blue One
    Joined: Feb 6, 2010
    Posts: 11,459

    Blue One
    ALLIANCE MEMBER
    from Alberta

  23. I went through many bits re-drilling the pin hole in leaf springs before I finally just put it on a mill. Bored through it like it wasn't there.
     
  24. I guess you guys haven't seen all the demos at the flea markets - seems easy enough for them to do - and if you're lucky you get a free set of Jinsu knives to go along with the drills plus a shammy to clean up!

    :rolleyes:

    Dennis
     
  25. remi
    Joined: Feb 9, 2008
    Posts: 58

    remi
    Member
    from nb, canada

    thats a good way to destroy the corners of a drill even in mild steel. drills are made to cut. for the best results drill a pilot the size of the web on the drill. any bigger and any step drilling is a waste of time. to figure out speed use this formula. (cutting speed x 4)/diameter of tool.

    as for the hardened steel, a carbide drill or endmill would do it. if its in the 60 rockwell range hss wont cut it no matter the cobalt content.
     
  26. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,657

    Rusty O'Toole
    Member

    Obviously this is done on thick metal or metal too tough to drill in the ordinary way. It is not dead accurate to the .001 of an inch but close enough for most fabrication work. You might be surprised how accurate you can get with a little practice.

    The trick is to have a tapered punch of the appropriate size. As I said, my friend used a WW2 surplus machine gun barrel. He had a lot of surplus equipment, he dealt in surplus airplanes and machinery right after the war.

    Anyway, he would mark out the holes with soapstone, cut the hole with the acetylene torch then quickly drive the punch into the red hot hole with a big hammer. The result was a perfectly round hole in 1/2" thick steel in seconds.
     
  27. the cement drill with a ton of down pressure proabbly gonna have to do it in a mill
    also MSC and others have stones to sharpen them, that helps, find one with a nice square edge
     
  28. BadCat68
    Joined: Oct 28, 2009
    Posts: 33

    BadCat68
    Member
    from C.R. MN

    i just finish drilling about 50 holes in hard motorcycle rotors. HSS standard drill and lots of hard cut oil. 550rpm. oil drill a little more oil and then more oil.

    [​IMG]
     
  29. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    How about hood pins? If you don't like the look, turn 'em upside down and hide them behind the grille opening.
    Or make a sliding piece that catches the knob on the latch without having to drill any holes, like the spring clip on a hydraulic cylinder pin.
    Or adapt a better catch out of something newer, maybe cable operated to keep the lookie-lou's out!
     
  30. anyone use a drill doctor to sharpen a carbide masonry bit. I can get some regular carbide bits from mcmaster for about $35.00 at bit, I was thinking about getting a drill doctor also.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.