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Thread: thread cutting on a lathe

  1. #1
    Join Date
    Feb 2010
    Posts
    8

    Default thread cutting on a lathe

    I have a problem cutting threads and I doint know if I am not engaging it at the wrong time or the clock is not in time if you will. The problem is that the threads doint cut the same all the time they overlap I start on 1 on the clock and keep starting it on 1 and it doesnt cut right. I f any one can help it would be great.

  2. #2
    Join Date
    Aug 2006
    Location
    Taylorsville Ky
    Posts
    5,882

    Default

    More info needed.

    What thread are you cutting, metric or imperial?

    What lead screw do you have, metric or imperial?

    Are you sure you have the right gear train setup for the thread your cutting?

    To me it sounds like your cutting a metric thread with imperial setup or an imperial thread with a metric setup. From your description it sounds like a gear train setup problem.

    This should get interesting.
    It's only ink and paper

  3. #3
    Join Date
    Sep 2008
    Location
    Merkel, Tx
    Posts
    719

    Default

    benniet,

    I am fairly new at this machining game, and just recently started single point threading on my lathe. At first I was having the same trouble that you are describing. I found that, on my lathe, I have to "lead the mark" a little to get the half nuts to engage on the right point.

    I think every lathe is a little different and it just takes some practice to engage the half nuts at the correct time.

    Tim

  4. #4
    airsmith282 Guest

    Default

    look at the threading dial on your lathe now pick a number 1 to 4 and which ever number you pick you have to use that same number each time you engauge the carriage. also make sure your angle on the compound is set right , and make sure the gears you are using are set to the TPI you need and start making threads .. thats abotu all there is to it in the short version,

    if you can't get the hang of threading then just buy the tap and die you need and do it that way ,, besides you can justify the expense to the wife really easy.

    i hate the hassel of the set ups. to time consuming and there are some TPIs my lathe just wont do, so i go out buy the tap and die i need and its done..

  5. #5
    Join Date
    Nov 2006
    Location
    Louisiana
    Posts
    334

    Default

    Leave the half nuts engaged..

  6. #6
    Join Date
    Feb 2010
    Posts
    8

    Default

    My lathe is olny set up for standard threads I doint have any metric gears or lead screw.

  7. #7
    Join Date
    Jan 2010
    Location
    ny orange county
    Posts
    16

    Default

    i leave the nut engaged , then at the end of thread i pull out reverse spindle to go back then fowerd spindle for next cut.

  8. #8
    Dr Stan Guest

    Default

    Quote Originally Posted by benniet
    I have a problem cutting threads and I doint know if I am not engaging it at the wrong time or the clock is not in time if you will. The problem is that the threads doint cut the same all the time they overlap I start on 1 on the clock and keep starting it on 1 and it doesnt cut right. I f any one can help it would be great.
    Get a copy of Southbend's "How to Run a Lathe". It will be the best investment you ever make in your machining.

  9. #9
    Join Date
    May 2005
    Location
    Salisbury, MD
    Posts
    431

    Default

    The question is a little too general to answer specifically. The general answer is that the cutter is not being presented to the work at the appropriate place, obvious isn't it?

    Could be that the work is moving in the holding device (chuck or collet). Or the cutter is moving in a way that is not appropriate, possibly slop in the lead screw/nut (either on the carriage or the compound) or an incorrect set up.

  10. #10
    Join Date
    Nov 2008
    Location
    Suffolk, UK
    Posts
    1,812

    Default

    It can really only be a gearing issue. You need to tell what lathe you are using, what gear train you have set-up and what threads per inch you are trying to cut. A copy of the gear/thread table you are using would also be helpful.

    Phil

    Quote Originally Posted by benniet
    My lathe is olny set up for standard threads I doint have any metric gears or lead screw.

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