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welding on a lathe

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  • #16
    I Worked briefly for a firm which did a lot of work for a large concrete block works nearby
    Their big lathe was about 4 ft swing by 16 ft centres distance.
    The concrete plant was still largely a line shaft driven relic
    . One day they brought in the main shaft, about 4 inches diameter and fully 14 feet long with a very visible bend roughly in the middle. The fellow who ran the lathe set the shaft between 4 jaw and solid centre, found the middle marked it.
    Next he recruited the 4 welders and they got positioned to heat the shaft near the middle with rosebud ( Oxy Acetylene) burners.
    He set the lathe turning very slowly,once he judged that it was hot enough he climbed on the saddle, very carefully straddled the glowing shaft, one leg each side of the shaft, a helper handed him a large sledge hammer and when he judged appropriate gave the shaft a mighty blow.( To this day I wonder how his overalls did not catch fire)
    After about 3 or 4 such mighty blows he climbed off the saddle, squinted at the now straight shaft. waved the welders away and went for a cup of tea.
    He ran an angle grinder over the dents he created in the shaft once it cooled down enough to run his hand over the shaft, then the crane driver took the still warm shaft back to its home.
    Incidentally Joe, the machinist who ran the lathe built fabulous small model steam engines as his hobby.
    Happy memories. Regards David Powell.

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    • #17
      Originally posted by J Tiers View Post
      You see welding on the lathe all the time in the Pakistani videos. I never see the ground lead, so presume the current may be going wherever. That would be consistent with many other observed activities!
      They just weld the ground to the ways. When finished they remove it with the angle grinder then some judicious hammer blows to smooth out the high spots.

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      • #18
        I've done it a few times. Using the lathe to fixture while tacking parts with the TIG welder. I put the ground either on the back end of the spindle or on the work.

        I was more concerned about frying my VFD than damage to the lathe. Question: VFD off for sure but is it better to leave it plugged in to maintain earth or better to unplug it?

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        • #19
          Originally posted by dalee100 View Post

          Nah, sometimes you have to do what you need to do. I've never needed to weld anything in my lathe, but if doing so meant getting a critical job done vs not done, I would just get on with it. A lathe or mill is not some sacred artifact from the Honorable Ancestors. It's just a machine meant to be bent to my needs and goals. Not the other way around.
          If the job pays enough, even a 10ee is sacrificial. I guess that WAS the case in WW2.

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          • #20
            Holy geez. I didn't watch all of that first video posted by Jon, but:

            1. If he runs the jaws on that 3 jaw chuck out about one more scroll tooth he's going to be wearing them for a hat. Stupid, dangerous move.

            2. That is the worst Jacob's chuck wrench I have ever seen. A kid whacking the face gear teeth on the chuck with a hammer and chisel! Yikes. A chuck wrench can't be that expensive in Pakistan.

            3. I can't believe they didn't even attempt to straighten the axle.

            4. I wonder how long it lasted before it broke again. No post-weld heat treat means it's either not going to be very hard or it's going to be excessively hard and brittle.

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            • #21
              A never ending source of amusement those Paki vids! So many memorable ones and off on a tangent I go as usual. One world class great one was a truck wheel hub and securing nut. Step 1 make a nut from a casting. Step 2 bore an arbitrary diameter hole in said nut and thread it. Step 3 center the hub on the lathe with the coat hanger indicator then keep single pointing the OD thread until the nut fits. Step 4. Be sure to ship the 'select fit' nut with the hub.

              Oyeah,keeping with the thread, if it's too small weld it up with 7018's and try again.

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              • #22
                Originally posted by RB211 View Post

                If the job pays enough, even a 10ee is sacrificial. I guess that WAS the case in WW2.
                Probably just the opposite. Valuable precision machinery in short supply, not easily replaced wouldn't be sacrificed.

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                • #23
                  Originally posted by reggie_obe View Post

                  Probably just the opposite. Valuable precision machinery in short supply, not easily replaced wouldn't be sacrificed.
                  The 10ee's that machined the Uranium pretty much were sacrificed.

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                  • #24
                    Originally posted by Jon Heron View Post

                    Jon
                    I can see from 7,000 miles away that it was not lined up prior to welding. You'd think they would have noticed at the time. I could see the wobble before and after welding. It's start with him putting the point on the axle, because the end is not supported through the lathe. hahaha I wonder if they give warranty?
                    Last edited by RancherBill; 04-14-2022, 12:46 PM.

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                    • #25
                      Originally posted by RB211 View Post

                      The 10ee's that machined the Uranium pretty much were sacrificed.
                      They were chosen and purchased because they needed the precision of the 10EE and production use wasn't a one-off part or a shafting weld buildup.

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                      • #26
                        Nothing about lathes.... ten or so years ago we had a major earthquake in New Zealand, a city was badly damaged, railroad tracks torn aside and roads displaced one for lane-width sideways but this is about a milking shed with a rotating turntable that carried 50 cows at a time.

                        The earthquake buckled the turntable so that it would not longer run on it's peripheral rollers. Crowbars, jacks ropes etc were to no avail as the entire structure was just too springy. Until one guy who was not even involved in the repair asked if he could try. OK, he collected three or four arc welder and boxes of electrodes, he had people lay down beads where he had marked the turn table in several places and after a while called a halt. Everyone watched and waited until a mighty 'twang' was heard and the turntable jumped and fell into its proper track.

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                        • #27
                          I dont understand the " you gotta do what ya gotta do" mentality in this particular case. If ya gotta weld on the lathe, fine, just do it right. ground the workpiece, simple enough, there's just no need to sacrifice a machine as was the case in the 10EE uranium mill example (presumably, now too radioactive for any one to touch?).


                          and isn't part of "what ya gotta do," using the machine for future work? it is in my shop.


                          edit / add

                          i dont have or know anything of VFD's, but someone brought them up & I have -some- knowledge of electrics. only real electrical pathway is ground, hard to imagine that causing any problems for your VFD. but I'm happy to be proved wrong my someone who actually know what they are talking about
                          Last edited by mtraven; 04-14-2022, 06:39 PM.
                          "it is no measure of mental health to be well adjusted to a profoundly sick society." -- krishnamurti
                          "look deep into nature, and then you will understand everything better." -- albert einstien
                          "any intelligent fool can make things bigger and more complex...It takes a touch of genius - and a lot of courage to move in the opposite direction."

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                          • #28
                            The way I see it if a person has such little regard for his lathe that he's welding on it it doesn't make any difference where he pulls ground from.

                            JL.....

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                            • #29
                              Originally posted by JoeLee View Post
                              The way I see it if a person has such little regard for his lathe that he's welding on it it doesn't make any difference where he pulls ground from.

                              JL.....

                              Sir John welded damaged motor shafts in a lathe. Don't recall how he grounded the workpiece, though...

                              -js
                              There are no stupid questions. But there are lots of stupid answers. This is the internet.

                              Location: SF Bay Area

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                              • #30
                                I am pretty sure he used his "beater" lathe for that.
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                                CNC machines only go through the motions

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