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Tips for drilling work-hardening material?

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  • Tips for drilling work-hardening material?


    Recently I decided to make a few tailstock die holders in various sizes. Everything has been going OK until now, on the last step of the last holder. The steel I am using is (most likely) C45/1045. It came from the end of an old Jeep axle, and that is the grade of steel they used at the time. It tends to work-harden quite severely.

    It hardens if you try HSS on it.
    It hardens if you use dull carbide.
    It hardens if your center height is not good.
    It hardens if you go to the bathroom.
    It hardens if there's a squirrel outside.

    I got most of the job done by using CCGT 21.51 (060204) inserts, the razor sharp polished ones with a fairly fine feed (.0039) and a DOC of .010 at 440 RPM, diameter is 1.375. The finish is like a mirror. The die pockets were bored with a solid carbide micro bar (very effective).

    I was setting up to cross drill the set screw holes with a small carbide drill in the toolpost holder.... the drill got in to the full diameter and slipped, causing a dwell on the spot.

    The part is now harder than Superman's......... thing.

    The carbide is no longer drilling it there.

    What can I do to save the part? I have half a day in it and everything else is beautiful. I don't have any real heat treat abilities, certainly nothing controlled enough to anneal it. Just oxy-acetylene, and I'm not sure if there's anything in the bottles. And I really want to avoid that if possible.

    Any ideas or tips?
    Last edited by nickel-city-fab; 08-05-2020, 10:11 PM.

  • #2
    I was milling some 1045 bar stock at work today that I got from McMaster Carr.
    Was using carbide end mills in the Bridgeport. Finish was awful, but it did not get hard.
    I believe 4140 cuts better. It is kinda like cutting 1018 as far as trying to get a
    good finish, but not as gummy, and even harder to avoid swirl marks from the
    end mill.

    --Doozer
    DZER

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    • #3
      Originally posted by Doozer View Post
      I was milling some 1045 bar stock at work today that I got from McMaster Carr.
      Was using carbide end mills in the Bridgeport. Finish was awful, but it did not get hard.
      I believe 4140 cuts better. It is kinda like cutting 1018 as far as trying to get a
      good finish, but not as gummy, and even harder to avoid swirl marks from the
      end mill.

      --Doozer
      Ya think it maybe something else? There's only a limited range of materials that would have been a Jeep axle in the 1980's.
      Maybe the problem is that my carbide drills are all spotter drills.
      Cobalt M42 won't even touch this thing now -- just skates off.

      EDIT PS I'll send you a stub of this stuff if you want..... takes a beautiful finish when you finally get the setup dialed in
      Last edited by nickel-city-fab; 08-05-2020, 10:45 PM.

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      • #4

        Collect a bucket of ashes from a fire.
        Heat the part up nice and red with your blue wrench.
        Drop the part into the ashes and cover well.
        Come back tomorrow and try to machine it again.
        You don't have to get the whole part red, but the more the better.

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        • #5
          Heat it up red and cool slow where the drill /tap holes are. Repeat if necessary.... you did say tapping yes. Next get a good tap designed for mold steel... usually for set screws I try to drill thru, unless they need to be 90 degrees to each other.
          sorry , thought you were tapping a shaft
          we annealed induction hardened shafts this way to drill them.'
          Last edited by 754; 08-06-2020, 01:34 AM.

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          • #6
            Assuming this is for holding round dies, put the threaded hole in another position. The 180* out put a spot on it and another drilled and tapped hole. If any one asks what the dimples are for reply " They are for balance in high speed operations."

            lg
            no neat sig line
            near Salem OR

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            • #7
              I made some progress.

              During the previous machining, the chips were coming off a bright blue. The part was getting pretty hot. I slowed the RPM's all the way down to 50 RPM in back gears and took an OD cut.

              I had left more than enough meat on the OD to get away with .050 deep to get rid of the dimples. Taking .010 DOC per pass. The trick is to have dead sharp carbide low and slow, and I turned the feed all the way down to .002 per rev. Yes it took a while. But at least this way the chips never got warmer than yellow.

              Considering the lathe is 75 yrs old, I think its doing OK. I haven't tried the cross drilling again yet -- maybe in the morning.

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              • #8
                that is weird and never happened to me. c45 doesnt really "work harden" it needs a quench. so you ran the spot drill so fast that the area got to quenching heat? i think not. so it might have hardened some by cooling down, but if carbide wont toutch it i have no explanation.

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                • #9
                  Originally posted by dian View Post
                  that is weird and never happened to me. c45 doesnt really "work harden" it needs a quench. so you ran the spot drill so fast that the area got to quenching heat? i think not. so it might have hardened some by cooling down, but if carbide wont toutch it i have no explanation.
                  Its old jeep shaft so hardened possibly to somewhere 40HRC. Still shouldnt be huge obstacle for carbide
                  Otherwise C45 is pretty much like butter.
                  Location: Helsinki, Finland, Europe

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                  • #10
                    Originally posted by dian View Post
                    that is weird and never happened to me. c45 doesnt really "work harden" it needs a quench. so you ran the spot drill so fast that the area got to quenching heat? i think not. so it might have hardened some by cooling down, but if carbide wont toutch it i have no explanation.
                    I don't understand it either, but it is the second time I have tried to use this stuff, and its pretty difficult at best. I went through a *lot* of inserts today. I did drill the though hole with no problem, using ordinary HSS drills. Maybe its softer in the center?

                    Comment


                    • #11
                      Originally posted by MattiJ View Post

                      Its old jeep shaft so hardened possibly to somewhere 40HRC. Still shouldnt be huge obstacle for carbide
                      Otherwise C45 is pretty much like butter.
                      I'm starting to think it is softer in the center than at the outer diameter.... the OD turns just like hardened material, but the center hole drilled out with normal HSS with no problems.

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                      • #12
                        an axle should have been surface hardened only, so after taking of some material as apparently has been done it should be relatively soft. i assume i piece of the axle has been cut off. how? bandsaw? how did that go?
                        Last edited by dian; 08-06-2020, 02:35 AM.

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                        • #13
                          Originally posted by dian View Post
                          an axle should have been surface hardened only, so after taking of some material as apparently has been done it should be relatively soft. i assume i piece of the axle has been cut off. how? bandsaw? how did that go?
                          Cut off with the angle grinder. The ends were faced with no problems, about 75mm length. One end is (say) 38mm dia, the other end is turned down to 30mm. Then drilled (eg) 12mm thru, again with no problems. Bored with a miniature solid carbide bar, no problems. But turning the OD is just a nightmare.

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                          • #14
                            1045 should have manganese in the composition.....oh boy, is this stuff fun to drill The manganese containing alloy steels workharden like all get out...... In my experience so far, the only reasonable approach for performing drilling operations on Mn alloy grades is carbide tooling. Nothing short of a carbide drill is able to get a hole through this stuff in reasonable time and mental health expenditure (except a shaped charge perhaps). Curiously enough the Mn grades usually are quite machinable over the OD and also can be cut with a bandsaw, but drilling operations are just a nightmare.
                            Recently I machined a coupling for attaching sockets to a ratchet: the ratchet was operational and a quality tool, but the coupling that engages into the socket had been lost from it and someone cast the tool into the trash bin. So I decided to restore it by getting a standard socket wrench adapter and mating it to the ratchet handle. The operation required drilling into the wrench adapter and tapping it to be able to secure it to the ratchet handle with a bolt. Yeah....the coupling was made from manganese alloy steel. I gave up very quickly about the idea of drilling and tapping into that piece and went the opposite way: turned down the end that mates with the ratchet handle into a stud and threaded that with a regular HSS die to secure it with a nut instead of a bolt. Was done in 15 minutes as this was an OD operation, forget about drilling
                            Last edited by markx; 08-06-2020, 03:18 AM.

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                            • #15
                              I got lost here. What was the problematic part?
                              Drilling on OD, turning the OD or what?

                              If you were struggling to drill the setscrew holes you can forget about tapping those holes!

                              If you need to have it annealed but don't really care how soft it gets just build big fire on your backyard, throw the piece of steel there and retrieve it next morning from the ashes.
                              Location: Helsinki, Finland, Europe

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