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Parting stainless tube???

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  • #16
    I would suggest trying these:
    https://www.ridgid.com/us/en/stainle...tubing-cutters
    before attempting cutting them on the lathe.

    You will still have to de-burr them, but that's an operation that would be a great application for a lathe.
    You would still likely need to build a collet or bolster to hold the pieces.

    I use a 14" cold cut saw for many operations, but to cut thin tubing you would need to build a work holding device. An external collet that is fit to the table that matches the OD comes to mind. I don't know if I could find a blade with enough teeth to do this without cringing each time I began the cut.

    I have an bias to employ welding when ever I can. Is this an application that could tolerate a small weld seam? If so I would cut strip top length and butt weld with TIG.

    Hope you find a suitable solution.
    paul
    ARS W9PCS

    Esto Vigilans

    Remember, just because you can doesn't mean you should...
    but you may have to

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    • #17
      I would turn a plug to press/tap into the chuck end of the tube so the chuck won't crush it and it will grip better. A slow speed and continuous chip until you get almost through, then slow down the feed, lots of cutting oil, sharp too.

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      • #18
        I was cutting bike tubing by holding in the milling attachment with the long stock extending down tailstock way.
        The slitting saw was on arbor.
        It was slow, using cross feed, but accurate and angles are possible too.

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        • #19
          I didn't see it mentioned (may have missed it), but you're going to have a tough time with tubing like that in a steady rest. It's just not round enough to give you any rigidity. I would agree that cutting the rings in a bandsaw (HF 4x6) with a bimetal blade and finer pitch would be a lot less exciting than trying to part these off. If you must use a steady rest, make a collar to slip over and clamp or set-screw on the tube and run that in the steady. Also grind a slight angle on the end of the parting tool so that it breaks thru on the right side first, next to the ring that is being cut off.
          It's all mind over matter.
          If you don't mind, it don't matter.

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          • #20
            I’ll offer something completely different:
            Expanding mandrel on headstock, parting done next to expanding mandrel and rest of the pipe supported with steady rest and improvised second steady rest on the tailstock side...
            Location: Helsinki, Finland, Europe

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            • #21
              Originally posted by Rich Carlstedt View Post

              Make a round wooden plug ( ~2 1/2" OD) to fit as close as possible to the tube ( say .010" under the ID )
              Make the wood plug about 1/2" longer than the tube ( 12 1/2") and center drill both ends
              Now cut the long plug in half DIAGONALLY (!) and place it in the tube
              That's a really neat idea Rich. Have you tried cutting it in half lengthwise so that the slit cosses the cone for the center? It seems that would allow the centers to act like wedges and expand the plug more equally.
              At the end of the project, there is a profound difference between spare parts and left over parts.

              Location: SF East Bay.

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              • #22
                Originally posted by MattiJ View Post
                I’ll offer something completely different:
                Expanding mandrel on headstock, parting done next to expanding mandrel and rest of the pipe supported with steady rest and improvised second steady rest on the tailstock side...
                The wood mandrel was a pretty good idea. But I think this one is the winner. It'll take a bit of time to make such a mandrel but if given enough segments it would force the tubing evenly and both the ring and the "stock" sides can be supported fully. The trick will be finding a design that allows the mandrel to easily lock and unlock though.
                Chilliwack BC, Canada

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                • #23
                  Yeah, Im with the mandrel also Matt. The saw would be my option be the OP didnt say he was going that route.

                  16ga is not that thin. I have clamped it up in the 6-jaw no prob

                  one other item that makes working SS a dream for me is Moly-Dee by castrol. JR

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                  • #24
                    I don't know if I will be able to explain this clearly... In "The Shop Wisdom of Philip Duclos", he shows a simple and effective way of gripping internally using a homemade mandrel and a pin or some round stock.

                    He turns some bar stock to a close slip fit then cuts a flat on one side. The depth of the flat is equal to or just slightly greater than the diameter of the pin. I don't remember if he was using a ground pin or just a random bit of small round stock. I think it was about 1/8". Then he lays a pin on the flat, slips the work piece over it and twists the work till it grabs the pin and locks. Of course you turn the stock in the opposite direction of the chuck rotation so the cutting forces will keep the part locked. Once you are done, a quick twist to release the pin and the part comes free.

                    It is simple, effective and works blind.

                    bob

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                    • #25
                      Thanks for all the replies. I was able to get the 6-1" pieces parted off this piece of tubing. I used a HSS parting tool and a pretty slow speed, maybe a bit faster than I normally part mild steel with. I kept the feed (manual) hard and I actually stalled the machine a few times. I have a vfd on the lathe but had the the pulley set to 3rd fastest. I don't know if the vfd stalled or the motor but it picked right up whenever I removed the tool from the work. I then put the lathe in the slowest pulley combination and it was fine from there. The chips were mostly long ribbons as described by an earlier poster. I just happened to have a gear that was a close fit to the ID of the tube and I used it as a plug. I guess the tube was stronger than I thought because the 4 jaw didn't cause the tube to tighten down on the plug. It was cranked down pretty good too.
                      The main issue was the out of roundness of the tube. If it was perfectly round it would have been much nicer. The out of roundness made for a lot of chatter until I got into a full cut. I got nearly all the way through and backed out the parting so I could deburr the OD with a file. I put a live center in the tails to keep and ran it into the tube to catch each slice. I kept it soaked with cutting oil like I normally do when parting.
                      This was the first time I used the steady rest on this lathe and I've had it over ten years [emoji39]. I'm a hack hobbyist and I don't use the lathe much but I still love having it and I've used it countless times since I got it. It's an old Sheldon EXL 10" and I replaced the motor with a 4hp (way overkill but it was free) 3-phase unit. I recently did a complete repaint to it as well.
                      Thanks again for all the great advice. All of them made for a perfect example of how many ways there are to skin a cat.

                      Sent from my Pixel 2 using Tapatalk

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                      • #26
                        I used to cut 16 gauge steel tubing and stainless tubing. We would cut hundred of pieces in an hour or two and spend the next two days deburring. Then we got a cold saw. Tubes, solids whatever, no deburring. Perfectly square cuts and no chatter because the part is held on both sides of the blade. We can hold the length over 100 parts to within a couple of thousands no problem.

                        That was before. Somebody did something to our cold saw and it chatters like hell now. Dial indicator shows no wobble, no runout, blade perfectly square to the travel, new blades, new bearings on the shaft, factory preload settings, and in the motor, new worm gear, Vise has absolutely no play, had the motor tested on a $30K analyzer. Nada, Zip, Nothing wrong! Still chatters like hell. The reason we brought this saw in here in the first place is that it was extremely quiet. Very frustrating. May have to just buy a new one.

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