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Real professional turning, or horror show ???

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  • Real professional turning, or horror show ???

    While watching the 150+ YouTube videos on Shapers, I saw a 'you might also like' about big lathes.

    The video started normally - big clean sparkly shop, big huge lathe, big shaft, big tool, lots of coolant, nice surface. Everything I have come to expect from professional work.

    Then the video got (how shall I say this) it got confusing. This happened after the 1:30 mark. It showed a really rough forging being loaded into a old looking lathe in a somewhat dingy shop. Then they started to turn it and the sound it made varied from what I would expect from dragging an anchor across a concrete parking lot to something that sounded like crushing rocks while frying bacon. They didn't use coolant. I expected the awful noise to stop once they had the scale off. But it didn't - even when they got the scale off the thing continued to make a rock crushing bacon frying noise. Still no coolant. The chips coming off weren't blue and smoking ... at points they were literally red hot. At several points the tip of the carbide insert was glowing ORANGE HOT. Towards the end they had two tools side by side advancing down the length of the shaft and the chatter was incredible.

    What makes this confusing is that it seemed like it is everything I try NOT to do while turning. Yet, there was a pile of these finished shafts shown in the closing scene, so I assume these people are professionals.

    Could people more experienced in the art of turning give me some comments about what they are doing? Are they showing me the way that real professionals do it, or is this a horror show which demonstrates that doing many things wrong can still produce a passable product (sometimes)?



  • #2
    The sizzling popping sound is the chips being ripped off the parent metal and folding up. If you watch, his finish passes are quite fine, but his roughing passes take a solid bite. Since the forgings are so rough, he's got a lot to remove. That being said, the resonance that was set up when he was finishing the small end would drive me up the wall.

    Since I assume this is a money making shop, the quickest job that produces and acceptable result is, from the shop owners perspective, the best job.

    Comment


    • #3
      They are debarking rough forgings which are also heat treated.Happens all the time,common practice in industry.A few weeks ago I had to do similar to some 6" hot finished 4140HT bar.While not as dramatic as the video,the bar was a good 1/8" over sized and 1/16" out of round.The first two passes where nasty.but the last two were smooth as silk.

      If you want to see some heavy machining,checkout the Binns Superlathe video-

      https://youtu.be/j87WW-jGmrU
      I just need one more tool,just one!

      Comment


      • #4
        Production turning (or just large/heavy turning in general) is certainly a bit different. Most of what was shown was pretty reasonable, though maybe not the best practice. It's actually fairly common to cut steels dry, especially for roughing; the high heat can improve tool life with certain insert materials and coatings. For instance, high-performance coatings like TiAlN don't form their lubricious oxide film until a certain temperature is reached. High temperatures can also assist the cutting process by softening the material just ahead of the cutting edge, making it easier to cut; ceramic inserts actually rely on this fact, they don't really work until you crank up the speed (and thus heat). It's not really something you want to try on a small manual lathe! The sizzling was a good sound, I have occasionally encountered that even on my little bench lathe. It mostly seems to happen with large depths of cut at slow speeds.

        Judging by how much the toolpost seemed to move under the interrupted cuts, this lathe probably has a fair bit of wear, not too surprising if it's been running such jobs day in and day out for years. That may have something to do with the chatter at the far end, but that's only a guess. The chatter near the middle of the shaft was tolerable, but I would also guess that since it was a heavy roughing cut, they just decided to roll with it and finish the cut rather than fiddle with adjustments when the heavy chatter set in. It wasn't really hurting much - just annoying. Again, not particularly good practice, but more or less serviceable. Finally, it's important to note that with individual forgings like that, running on an old and somewhat tired manual lathe, they aren't going to have an optimal process and there will be a fair amount of "let's try this and see how it goes" - a far cry from well-optimized volume production that is perhaps more typical in such "professional" shops.

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        • #5
          That's how it goes when you have to make money out of it.
          Maybe the lathe would be sturdier in ideal case but it looks like it got the job done so..

          This has the same sizzling going on:
          https://www.youtube.com/watch?v=dsSo5qOGk6c

          Those chips are bigger than what home shop guys often use as a raw stock!
          Dimensions lie but the insert edge is 1.5" inches and cut of depth not far from that!

          Comment


          • #6
            The lathe is an old, badly abused DSG. Probably one of the best lathes ever made, still doing pretty good work on a heavy turning job. I suspect this lathe might have been sold out of a UK or European shop for a low price and shipped halfway round the world to end up doing this job.
            Bill

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            • #7
              At 10:43 - what is the purpose of the top finger on the steady? Is that a chip shield or is that some kind of plain bearing?
              At 11:18 it appears there is some kind of flat faced live center in the tailstock - what is the purpose of this? Additional support to reduce chatter or resonance?

              Comment


              • #8
                The steady thing looks like an oiler for the work, although the steady seems to have rollers. Looks like some lube on he part.
                1601

                Keep eye on ball.
                Hashim Khan

                Comment


                • #9
                  I've seen that second clip in another video where the material was identified as inconel. VERY tough stuff and being oxidation resistant the chips don't change color with temperature - but, rest assured, they are plenty hot. Chips like that fly and stick: they will burn right through your overalls and your jeans to raise a blister the size of a quarter on your leg before you can dance clear of the trajectory. I used to wear a leather welder's apron when I was roughing on a big machine tool.

                  Large turning work might benefit from coolant but coolant is usually avoided on large machine tools on account of the system volume required to ensure consistent return and because of the mess and sanitation problem, spoiled coolant attracts rats for some reason..

                  Loud thumping noises are not uncommon where heavy interrupted cuts are involved - you can feel it with your feet - as is incipient resonances and chatter.

                  What you see is aggressive large scale lathe work, efficiently conducted but like the opera tenor observing a light bulb being screwed in by another tenor, I'd have done it better. Bad part about retirement is I miss that kind of work. They give you a big forging on a flat car and a big lathe built in 1952 and by the end of the week you have a shaft or a turbine rotor pretty well roughed out and quite literally tons of chips. That kind of stuff I'd pay them to work. I was nearly a hundred lb lighter in those days and my torso tapered the other direction.
                  Last edited by Forrest Addy; 12-31-2017, 12:57 PM.

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                  • #10
                    In the first part, there IS coolant.
                    1601

                    Keep eye on ball.
                    Hashim Khan

                    Comment


                    • #11
                      Originally posted by dockterj View Post
                      At 10:43 - what is the purpose of the top finger on the steady? Is that a chip shield or is that some kind of plain bearing?
                      At 11:18 it appears there is some kind of flat faced live center in the tailstock - what is the purpose of this? Additional support to reduce chatter or resonance?
                      The top roller isn't rotating so I would guess that they are using a lubricated pad instead, perhaps to suppress chatter.

                      The centre looks normal to me, but the part apparently should not have a centre in the end, so I think they are using a big nut to fit over the centre so that they can put some pressure on the work. This might also help reduce chatter.

                      The material looks like a very tough forged steel, so not easy to rough machine.
                      Bill

                      Comment


                      • #12
                        During the heavy sizzling cuts there's a transition to an interrupted cut right at 2:50 that sure looks to me like the cutter and tool post are "nodding" down from the force of the cut. Not something I expected to see even given that it is tough material. Sort of suggests that the maintenance on the lathe is lacking and the gibs need to be adjusted or the machine set up so there's less overhang in various aspects in the cross slide, compound and tool post arrangement.

                        Finished watching it. All in all I wonder about the modern stuff at the first part and the old machine in the second. I don't read Japanese or whatever it was but I wonder if this was intended to show that while some use the latest computer controlled stuff that the old ways worked and still do work. Certainly the final result came out just lovely.
                        Last edited by BCRider; 12-31-2017, 02:41 PM.
                        Chilliwack BC, Canada

                        Comment


                        • #13
                          Originally posted by BCRider View Post
                          During the heavy sizzling cuts there's a transition to an interrupted cut right at 2:50 that sure looks to me like the cutter and tool post are "nodding" down from the force of the cut. Not something I expected to see even given that it is tough material. Sort of suggests that the maintenance on the lathe is lacking and the gibs need to be adjusted or the machine set up so there's less overhang in various aspects in the cross slide, compound and tool post arrangement.
                          Yeah and running it so cut presses tool it into holder, instead of out of it maybe? Could be the downward forces on tool in combination with the set screws are so great its moot.

                          Can see how carbide revolutionized the bottom line.. it's all about the big stuff.

                          Comment


                          • #14
                            Originally posted by willmac View Post
                            The lathe is an old, badly abused DSG. Probably one of the best lathes ever made, still doing pretty good work on a heavy turning job. I suspect this lathe might have been sold out of a UK or European shop for a low price and shipped halfway round the world to end up doing this job.
                            Not sold out and not in china... chinese folks just ripped the video out of here:
                            https://www.youtube.com/watch?v=VGok54DdYAo

                            Tooltek precision in UK, specialized in turning Inconel..

                            Their channel has also other interesting videos:
                            https://www.youtube.com/user/Tooltekprecision

                            Comment


                            • #15
                              Roughing out and heavy turning may look or sound crude , but in most shops it's try to make money.. and hard on equipment.
                              Looks horrible to a hobby machinist.
                              A buddy of mine showed me a lathe they broke in their shop. I am guessing 24 or 26 inch swings maybe 30.
                              They were turning about 14 inch diameter 4340 , and taking off around a 600 thou or 5/8 cut, which they did often.
                              Except this time the head stock gears grenades and let go. . He showed me the unfinished workpiece with the mark on the cut where it let go. The work was 30 of 36 inches long I bet the material cost more than some of our lathes cost.

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