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((((oo)))).....threading

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  • ((((oo)))).....threading

    How the heck do you guys thread on a lathe?

    Tried some tonight and made me right (((dizzy))), watching that cut progress down the shaft!

    4 years in the Navy and never got sea sick until tonight.
    Len

  • #2
    I enjoy single point threading. I think that it is one of the more challenging things that I do on the lathe. It's kind of like driving a motorcycle, it's a two handed operation that takes timing and coordination. I'll give you that it can be a little mesmerizing but, when it's done right I get a real feeling of accomplishment. If you want to have some real fun, thread up against a shoulder......
    "Those who hammer their guns into plows will plow for those who do not."~ Thomas Jefferson

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    • #3
      Good practice is to stare at a barbershop sign spinning 'round & 'round

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      • #4
        Here's how I do it:
        http://www.youtube.com/watch?v=0q_q53wsyHU

        I put the compound at 29.5 degrees, align the 60 degree cutter at 90 degrees to the work, then feed in with the compound. I don't disengage the half-nuts, I back out the cross-feed for clearance, reverse the motor to return to the start, run the cross-feed in to to the preset stop, advance the compound a bit, then take another cut.

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        • #5
          LOL

          I think its fun too, but you get a big diameter piece with coarse threads and it is pretty dizzying!

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          • #6
            I'll admit coarse threads are a little intimidating at 150 rpm, especially against a shoulder. Take 8 tpi for example, for every revolution of the spindle your an eighth of an inch closer to disaster. You can thread in reverse and cut away from the shoulder for example. This will take some of the anxiety out of the equation.

            Or do what a lot of folks do and use a VFD.
            Timing and rhythm are still key elements, as well as proper tool bit setup. But life is sweet and relaxing in the slow lane. I used to dread threading coarse pitches but now I look forward to them, even internal ones.
            Home, down in the valley behind the Red Angus
            Bad Decisions Make Good Stories​

            Location: British Columbia

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            • #7
              Originally posted by dp
              Here's how I do it:
              http://www.youtube.com/watch?v=0q_q53wsyHU

              I put the compound at 29.5 degrees, align the 60 degree cutter at 90 degrees to the work, then feed in with the compound. I don't disengage the half-nuts, I back out the cross-feed for clearance, reverse the motor to return to the start, run the cross-feed in to to the preset stop, advance the compound a bit, then take another cut.

              That's one way to do it. I was taught to disengage the half-nuts after finishing each cut and then to move the compound back. Then when the counter comes to the proper mark, I re-engage the cut.

              On my lathe, whch brand shall go nameless to keep from offending in case Milacron is visiting, I only release the half-nuts for an American thread. The instructions that come with the lathe specify that, for a metric cut, you don't release the half-nuts. You simly stop at the end of the thread, move the tool out and then reverse the lathe back to your start point as you say.

              In my case, this is because I have an English lead screw on the machine, at least that's what the instructions say regarding metric threads.

              It's perfecly OK to leave the half-nuts engaged for American threads as well, however. On my lathe, the lowest speed is 70 rpm which is excellent for threads.
              Last edited by gnm109; 03-20-2008, 12:51 AM.

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              • #8
                read a book

                Get a copy of L.H. Sparey's book The Amateur's Lathe, it is old and basic, but still the standard in good technical literature.

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                • #9
                  Originally posted by QSIMDO
                  4 years in the Navy and never got sea sick until tonight.
                  hehe, now you have do them without a groove at the end of the thread, just a nice swift retraction of the cross feed at exactly the right spot to produce a clean end of the thread
                  in Toronto Ontario - where are you?

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                  • #10
                    Originally posted by QSIMDO
                    Tried some tonight and made me right (((dizzy))), watching that cut progress down the shaft!
                    LOL I know what you mean.. I used to watch a buddy of mine thread four inch diameter stuff on the big 20" Reed Prentice.. I would get focused on the cutting tool and I was on the back side of the lathe. I would almost fall over because of the movement. Looked like the whole lathe was moving. But it was me!!! Haaa. Mesmerizing.. JR

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                    • #11
                      This is a great link, I was reading it last night. On "page two", they describe how to thread.

                      http://www.americanmachinetools.com/...se_a_lathe.htm

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                      • #12
                        To keep from ralphing, I just focus on one thread an follow it down to the end. It's especially helpful if you follow the one your tool is in.
                        Stuart de Haro

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                        • #13
                          Did a 1" x 8 Yesterday in 12L14 Peice of cake. Today did a
                          5/16 x 24 in a chunk of hot roled MY GAWD what a pain. That stuff
                          looks like it may be closely related to a porkypine. :-(
                          ...lew...

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                          • #14
                            Originally posted by QSIMDO
                            Tried some tonight and made me right (((dizzy))), watching that cut progress down the shaft!
                            I don't watch it. In fact I turn off the lights in the shop, to avoid temptation ... and also save valuable $$$s on the electric bill.

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                            • #15
                              it can be fun to thread...... but if you do the trick of backing out the tool and disengaging the halfnuts, be very darn sure that the spin of the dial you will use to retract the tool is in the CORRECT DIRECTION!

                              I do that usually, because I like the look of the thread that results. I HAVE managed to turn the dial the wrong way. That DID result in a surprise so I try very hard not to do that. And I very much dislike using the technique when people are watching.....................
                              2730

                              Keep eye on ball.
                              Hashim Khan

                              Everything not impossible is compulsory

                              Birds are NOT real, they are spying on you

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