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  • Turning Brass

    I've been asked to make some end plugs for a set of tubular bells for the local high school's concert band.
    Tubular bells are made from chrome-plated brass, both tube and plug. The plugs are soldered into the tube, and the whole lot is then plated.
    So I will have to turn the plugs from brass bar, which I have never turned before.
    What are the fish-hooks when turning brass? What angles should I grind on the HSS tool? How do speeds compare with those for mild steel?
    Thanks in advance.

  • #2
    Originally posted by Mike Burch View Post
    How do speeds compare with those for mild steel?
    Thanks in advance.
    Prolly depends on what make up of the brass. But I would go with the highest speed for finishing and a much lower speed for drilling.

    Are you making it from a round and drilling the canter and profiling the outside?

    I would go with a very sharp half moon point on a slightly positive rake? Help me out also guys, I like brass.

    Cant wait to see the finished product. JR
    My old yahoo group. Bridgeport Mill Group

    https://groups.yahoo.com/neo/groups/...port_mill/info

    Comment


    • #3
      Originally posted by Mike Burch View Post
      What are the fish-hooks when turning brass
      Solly, forgot to answer that one. I dont get curls with brass. My machine is not strong enough to really hog it out.

      I get not dust but very tiny curls, might need a maginfying glass to see then. I have to take light depth and a lil faster feed (x-y). JR
      My old yahoo group. Bridgeport Mill Group

      https://groups.yahoo.com/neo/groups/...port_mill/info

      Comment


      • #4
        Brass

        Originally posted by Mike Burch View Post
        I've been asked to make some end plugs for a set of tubular bells for the local high school's concert band.
        Tubular bells are made from chrome-plated brass, both tube and plug. The plugs are soldered into the tube, and the whole lot is then plated.
        So I will have to turn the plugs from brass bar, which I have never turned before.
        What are the fish-hooks when turning brass? What angles should I grind on the HSS tool? How do speeds compare with those for mild steel?
        Thanks in advance.
        Brass wants ZERO rake to avoid digging in, and high surface speed, along with aggressive feed.

        Dub off any drill bits, use HSS . carbide inserts may have rake that is not needed.

        And SHARP! SHARP! SHARP!

        Did I say the tools edges need to be sharp?

        Comment


        • #5
          Originally posted by Mike Burch View Post
          I've been asked to make some end plugs for a set of tubular bells for the local high school's concert band.
          Tubular bells are made from chrome-plated brass, both tube and plug. The plugs are soldered into the tube, and the whole lot is then plated.
          So I will have to turn the plugs from brass bar, which I have never turned before.
          What are the fish-hooks when turning brass? What angles should I grind on the HSS tool? How do speeds compare with those for mild steel?
          Thanks in advance.
          Brass is a fairly easy materials to cut. The only substantial difference on tool geometry compared to mild steel is the top rake angles. For mild steel the most common angle to shoot for is around 7 degrees positive. When cutting brass the rake angle should be zero, so that the cutting edge is scraping the material away rather than cutting into the work. This scraping action is done because most brass is soft enough to risk a positive rake angle allowing the tool to dig into the work, and possibly pull the stock from the lathe chuck.

          As for cutting speeds when using HSS, for most applications where 100fpm works for mild steel, simply up the speed to around 150fpm for brass. Also, where a cutting oil is often used for mild steel, brass can be cut dry.

          Comment


          • #6
            I did some machining of brass to make an air fitting for my Sleep Number bed. I used pretty slow speed and feed. Got curls with heavier DOC and powder with very light DOC. No problem using my HF 9x20 lathe.

            http://enginuitysystems.com/pix/Slee...tting_1817.AVI (59M)

            http://enginuitysystems.com/pix/Slee...tting_1818.AVI (81M)

            http://enginuitysystems.com/pix/Slee...tting_1821.AVI (61M)

            This is the grooving tool I used. Maybe 2-3 degrees positive top rake:



            It needed a bit more clean-up, but "turned out" OK:



            Last edited by PStechPaul; 06-23-2017, 03:03 AM.
            http://pauleschoen.com/pix/PM08_P76_P54.png
            Paul , P S Technology, Inc. and MrTibbs
            USA Maryland 21030

            Comment


            • #7
              [QUOTE=PStechPaul;1122675]I did some machining of brass to make an air fitting for my Sleep Number bed. I used pretty slow speed and feed. Got curls with heavier DOC and powder with very light DOC. No problem using my HF 9x20 lathe.

              http://enginuitysystems.com/pix/Slee...tting_1817.AVI

              I enjoyed the vids and pics. Thanks. JR
              My old yahoo group. Bridgeport Mill Group

              https://groups.yahoo.com/neo/groups/...port_mill/info

              Comment


              • #8
                Originally posted by Mike Burch View Post
                I've been asked to make some end plugs for a set of tubular bells for the local high school's concert band.
                Tubular bells are made from chrome-plated brass, both tube and plug. The plugs are soldered into the tube, and the whole lot is then plated.
                So I will have to turn the plugs from brass bar, which I have never turned before.
                What are the fish-hooks when turning brass? What angles should I grind on the HSS tool? How do speeds compare with those for mild steel?
                Thanks in advance.
                Mike: Don't the bells have to be tuned? Putting the plug in the ends, I would think that the sound would change.

                Sarge41

                Comment


                • #9
                  Thanks, all. Most helpful stuff there. Nice work, too, Paul.
                  Sarge, yes, they do have to be tuned. This is done after the plug is placed by grinding off the open end to bring the pitch up to the desired frequency (the tube having been cut too long in the first place). Actually, for serious orchestral use, the tuning is somewhat more complex, with a fair bit of magic involved for which I lack the requisite incantations. For school use, tuning the main note will have to suffice.
                  I wasn't expecting the tubes for a week or two, but to my surprise they were brought to me only a couple of hours after I'd started this thread. There are only twelve of them, not the thirteen required for a complete octave, and they turn out to be made from steel! Seamed tube, at that, and so thinly chrome plated that the rust is beginning to show through. They are seriously crude, and certainly not professionally made. I'll make them some caps from mild steel, so at least the things will be proof against being played with schoolboy exuberance.
                  So thanks for the help, guys, and I'll remember it for the future in case I ever do have to turn brass (hideously expensive stuff and hard to find here in NZ).
                  Cheers!

                  Comment


                  • #10
                    As others said you do not want a positive rake. Zero rake and don't be afraid to use an aggressive feedrate. I'm not really a lathe guy but for say a 1/4" end mill I'd go up to .003" IPT

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                    • #11
                      One question - you wrote that plugs are soldered into the tube. I heard that high temperature will "temper" brass and make it unsuitable for bells (as far i remember - brass will require hammering or long time to harden again ). Is soldering temperature to low too soften brass or tubular bells aren't so picky?

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                      • #12
                        just what CalG said, exactly. There is nothing nicer to machine than 360 brass

                        One question - you wrote that plugs are soldered into the tube. I heard that high temperature will "temper" brass and make it unsuitable for bells (as far i remember - brass will require hammering or long time to harden again ). Is soldering temperature to low too soften brass or tubular bells aren't so picky?
                        good point. soft soldering temps should be fine, silver soldering temps will anneal and are an issue. afaik brass doesn't temper as you would think of steel tempering - ie a letting down various amounts depending on what temp its taken to.....I don't think much happens until you get it 1000 or 1100F at which point its annealed
                        Last edited by Mcgyver; 06-23-2017, 08:59 AM.
                        .

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                        • #13
                          In my other hobby of model airplane building I've soft soldered a fair amount of brass shim stock and tubing. Soft soldering does not anneal or temper back any spring like qualities in the brass by enough to notice, if at all.

                          It's likely a moot point in this case given that the tubular bells are being done with cheap seamed tubing.

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                          • #14
                            Check with whoever will do the plating before choosing your solder!

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                            • #15
                              Originally posted by The Artful Bodger View Post
                              Check with whoever will do the plating before choosing your solder!
                              Yes, I was a bit surprised to read that plating was done on top of solder. I imagine that using the wrong type of solder could result in problems. I won't be getting the job re-plated, so it won't be a problem here.

                              As far as the tuning is concerned, I have now measured all twelve tubes, and discover that each one is exactly 40mm longer than its shorter neighbour. This is ridiculous, of course, since to get a semitone in Equal Temperament (the same tuning as, e.g., a piano) they should in theory step up by a factor equal to the twelfth root of 2 (i.e., 1.059) give or take a small fudge factor. It's now obvious that this horrible collection is not tuned to anything at all, but merely intended to make a vaguely bell-like cacophony in no particular key! Bah.

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