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Thread: Square Threaded Rod

  1. #1

    Post Square Threaded Rod

    Does anyone know a source for square threaded rod. I need a piece about 20" long of 7/8"x6tpi. I need this to repair a bench vise. I don't have much experience but would try to make my own except my lathe will only go down to 8tpi. Thanks, D.M. Ammons

  2. #2
    Join Date
    Sep 2002
    Posts
    604

    Lightbulb

    One method of making square threads done by blacksmiths of the past is to take 2 square bars hold them side by side and wrap them together around a round bar in a continuous spiral with no gap between wraps. Take the spiraled square bars apart and braze one on the round bar which becomes the screw and braze a piece of the other into a bored hole of the vise to become the nut. Clean up with a file if necessary.

    Simple, easy, and brilliant.

    Not my idea of course.

  3. #3
    Join Date
    Apr 2001
    Location
    Maine
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    Post

    Truly a squre thread, or is it Acme? If square, I doubt you'll find it.
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    There are lots of people who mistake their imagination for their memory. - Josh Billings
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.

  4. #4

    Post

    Depending on the vise, maybe it would be easier to go with a standard acme threaded rod and replace the nut instead.

  5. #5

    Post

    It is truly a square thread. At first I thought I could make a new screw using a acme threaded rod. But when I gave it a closer look I saw it was a square thread. The nut fits in a special groove cast in the body of the vise so replacing it is not an option. The method used by blacksmiths has possibilites and I may have to give that a try. I have the nut(I'm doing this for a friend) and in rechecking it looks like about 3.5 tpi which sounds ,in my limited experience, kinda weird. Of course it's a internal thread I'm trying to measure and it's very difficult to measure an inch inside the nut which is about 4 inches long.Any help is appreciated.

  6. #6
    Join Date
    Apr 2001
    Location
    Maine
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    Post

    You say your lathe will only go to 8tpi...is there any chance you can change the stud gear? That's what South Bend does on their 9" and 10K lathes to get the really coarse threads, even on the lathes with quickchange gearboxes.

    (You'd want a stud gear with 2X the teeth of the "normal" stud gear; then 8tpi on the QC would come out as 4tpi, etc.)


    [This message has been edited by SGW (edited 03-22-2003).]
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    There are lots of people who mistake their imagination for their memory. - Josh Billings
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.

  7. #7
    Join Date
    Sep 2002
    Posts
    604

    Lightbulb

    Is there enough material in the nut to bore out and fit an acme threaded bushing pinned and brazed in place?

    Then make a new screw from acme threaded rod with a pinned and brazed on end.

    This is probably how I would do it.

    I would also make the bushing with a substantial shoulder (like a "tee" nut) so the clamping force is borne by the body of the nut and the brazing and pinning will only have to resist rotating.
    Good luck.

  8. #8
    Join Date
    Oct 2002
    Location
    Cheyenne Wyo
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    643

    Post

    I'll throw another fly in the ointment. If the jaw action is normal, that is clockwise to tighten, it'll be a left handed thread. Even a tougher critter to find.
    I'm here hoping to advancify my smartitude.

  9. #9
    Join Date
    Sep 2002
    Posts
    604

    Lightbulb

    Gizmo2,

    He's talking about a bench vise.
    Right hand thread, clockwise to tighten.

    A milling vise is another story.

    No flies and no ointment necessary

  10. #10

    Post

    Acme threaded rod and matching barrel nuts can come straight from the McMaster catalog.

    Steve

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