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  • drilling 3/8" hole in 3/4" threaded iron pipe

    Hello,

    For a project of mine, I need to drill at least two 3/8" holes directly through a piece of 3/4" threaded iron pipe. What's the best way to do this?

    Another post on this forum recommended a carbide-tipped hole saw, but that appears to be for creating a much larger hole (I haven't seen a 3/8" hole saw... do they exist? And is this what I should be looking for?).

    I've tried several cobalt metal bits, but they only seem to dig in for a millimeter or so, and I can't get any further (even a 1/8" bit doesn't dig in any further). Any thoughts?

    Thanks,
    Jeff

  • #2
    Re: drilling 3/8" hole in 3/4" threaded iron pipe

    cobalt will work drill slow. If possible use a drill press, it will drill that 3/8 hole in seconds

    Comment


    • #3
      Re: drilling 3/8" hole in 3/4" threaded iron pipe

      Hmm... I was originally using the slowest setting of the drill press; I'll switch back to that. Do you know, roughly, what RPM is best for drilling black iron pipe?

      Also, about how much pressure? Should I be putting a lot of weight on it, or light pressure and let the bit do the work?

      Thanks,
      Jeff

      Comment


      • #4
        Re: drilling 3/8" hole in 3/4" threaded iron pipe

        black pipe is usually a fairly soft steel, you may jsut have got a "bad" piece, and need to try a different piece, some steel can have some hard spots in it, much of the old machinery I have salvaged steel out of can really be interesting some will drill like butter, and some will burn up a bit in a few seconds, very inconsistent quality, most of the new steel normally much better, but some of the import pipe has inconsistencies in it, but black pipe should drill very easly, actually I have ran into some poor pipe that threads hard (thread tear) but not so hard one can not thread or drill it.
        (I am guessing you either have some different type of pipe (not black) or tube such as Chrome Molly tubeing, or a exceptional poor quality of steel, or your running the bit in reverse),
        Push sticks/blocks Save Fingers
        ~~~~~~~~~~~~~~~~~~~
        "The true measure of a man is how he treats someone who can do him absolutely no good."
        attributed to Samuel Johnson
        ~~~~~~~~~~~~~~~~~~~
        PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

        Comment


        • #5
          Re: drilling 3/8" hole in 3/4" threaded iron pipe

          got mag drill with annular cutters?? I do
          I can build anything You want , if you draw a picture of it , on the back of a big enough check .

          Comment


          • #6
            Re: drilling 3/8" hole in 3/4" threaded iron pipe

            Try these, they are anularcutters for a regular drill.
            http://www.hougen.com/cutters/sheetmetal/Rotacut.html
            Put your pipe in a V block in the drill press and have at it.

            Comment


            • #7
              Re: drilling 3/8" hole in 3/4" threaded iron pipe

              Originally posted by BHD View Post
              black pipe is usually a fairly soft steel, you may jsut have got a "bad" piece, and need to try a different piece, some steel can have some hard spots in it, much of the old machinery I have salvaged steel out of can really be interesting some will drill like butter, and some will burn up a bit in a few seconds, very inconsistent quality, most of the new steel normally much better, but some of the import pipe has inconsistencies in it, but black pipe should drill very easly, actually I have ran into some poor pipe that threads hard (thread tear) but not so hard one can not thread or drill it.
              (I am guessing you either have some different type of pipe (not black) or tube such as Chrome Molly tubeing, or a exceptional poor quality of steel, or your running the bit in reverse),
              Sounds good, I'll give it another try; drill's definitely going forward -- I was initially drilling with a press. To be sure, though, the pipe says "Nipple - Mamelon 584-240HC" on it (Mamelon, presumably, is french for nipple). I don't know much about piping, and that number designation there, so if it sets off any red flags, please let me know

              Thanks,
              Jeff

              Comment


              • #8
                Re: drilling 3/8" hole in 3/4" threaded iron pipe

                from the searchers I did it appears to be standard black pipe,
                http://www.hardwareandtools.com/invt/u194574

                http://www.drillspot.com/products/91...le_40_Cut_Pipe

                I would use a press if available as well, I have drilled holes in black pipe and have never had problems like you describe, I made a burner for a PVC tubing bender, and had a large number of holes in, and in my building of things I use black pipe for many things, saw and drill thread, it often and have never ran into the kind of hard spots your describing, I have on other steel (as said before), IF it was that hard in general there is no way one could field cut or thread it, with out special tools. definitely not normal pipe tools,

                most of the drill bits I use are jsut standard off the shelf high speed steel drill bits, from the hardware store, most of my larger bits are jsut lower cost ENCO import bits, (over 1/2") nothing special, and I hand sharpen them,
                normally the only problem I would say to watch out for is when it goes through it will grab fairly good as the piece your drilling through is curved and will try to catch (unless you have very good control on the feed of the bit) and spin the pipe, should not be any problem in the drilling of the steel it self,
                Last edited by BHD; 12-04-2008, 01:04 PM.
                Push sticks/blocks Save Fingers
                ~~~~~~~~~~~~~~~~~~~
                "The true measure of a man is how he treats someone who can do him absolutely no good."
                attributed to Samuel Johnson
                ~~~~~~~~~~~~~~~~~~~
                PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

                Comment


                • #9
                  Re: drilling 3/8" hole in 3/4" threaded iron pipe

                  All you need is a HSS 3/8" drill bit using a drill press. Use a set punch so the drill bit doesnt dance around. Use plenty of oil and apply constant moderate pressure. This is a simple job. The steel is soft.

                  Comment


                  • #10
                    Re: drilling 3/8" hole in 3/4" threaded iron pipe

                    Drilling in steps can make drilling easier. Start with smaller drills and increase till you get what you want.

                    Comment


                    • #11
                      Water pipes

                      Water pipes


                      I am thinking about buying some wholesale water pipes from this company in China http://www.liangdianup.com/tobacciana_z.htm
                      but I am not sure if they are legal to bring in to the states? What are the laws on water pipes, bongs, and pipes?

                      Comment


                      • #12
                        Re: drilling 3/8" hole in 3/4" threaded iron pipe

                        File the pipe surface flat with a small, coarse square bastard file, or use one of the mini grindstones that fit into a hand drill with a screw tight arbor.
                        When you have flattened the pipe surface such that you are almost through the pipe wall smack the pipe with a strong metal punch to start a hole.
                        Use a step drill in a drill press until you reach 3/8" at the top surface of the pipe.
                        Change the drill to a regular HSS 3/8" drill bit to finish the hole down to 3/8" through the whole pipe wall.

                        Step drills will work at slow speed and have a "smoother" cutting action. If you have a variable speed drill that can lock in the speed then all the better. If you don't, then adjust your speed trigger and hold the trigger in place with a thin electrical tie wrap.

                        I use one of those portable drill stands that have a holder to grab above the drill chuck where the drill support arm grabs on. A small vise attached to the drill table is all you need. You will get excellent control for pressure exerted on your work.

                        I bought one of the cheap($70.00 CDN.) 2 speed hammer drills from Ryobi and it works like a charm for all small drill press drilling and regular work as well. I keep the drill press in the truck at all times and use it to do holes for mechanical tees when repairing/replacing underground parking sprinkler pipe that has welded piping.

                        Danny

                        Comment


                        • #13
                          Re: Water pipes

                          Originally posted by newnew View Post
                          Water pipes


                          I am thinking about buying some wholesale water pipes from this company in China http://www.liangdianup.com/tobacciana_z.htm
                          but I am not sure if they are legal to bring in to the states? What are the laws on water pipes, bongs, and pipes?
                          No no newnew. Wrong forum.

                          Comment


                          • #14
                            Re: Water pipes

                            Originally posted by newnew View Post
                            Water pipes


                            I am thinking about buying some wholesale water pipes from this company in China http://www.liangdianup.com/tobacciana_z.htm
                            but I am not sure if they are legal to bring in to the states? What are the laws on water pipes, bongs, and pipes?
                            newnew, Waterpipes, Bongs and regular pipes should be no problem.

                            Please contact: 202-456-1414 Eastern Time

                            Tell um Okiebill sent ya

                            Comment


                            • #15
                              Re: drilling 3/8" hole in 3/4" threaded iron pipe

                              No takers on calling the number????


                              If you do you will get a great laugh!

                              Okie

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