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  • 3 wire thread measuring

    I've been trying to measure thread depths using the 3 wire method without much success. My problem is how to hold all 3 wires steady and in the threads while making a measurement, especially with the work still on the lathe?

    Am I making this harder than it really is?

  • #2
    What?! You don't have 3 hands?

    A small chunk of modeling clay, or some tape, helps.
    ----------
    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.
    Don't own anything you have to feed or paint. - Hood River Blackie

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    • #3
      Grease, blop of grease and one wire on the bottom, blop of grease and two wires on the top. Open your mic up a bit wide, catch the bottom wire, then come down on the top two wires. A piece of cardboard under the chuck helps for when you drop one.

      I've also seen people stick them into sponges, that seems to work pretty well, though I'm comfortable with grease.

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      • #4
        Also, check Marv Klotz's site for 3 wire calcs (among many other workshop/maths utilities)

        http://www.myvirtualnetwork.com/mklotz/
        Just got my head together
        now my body's falling apart

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        • #5
          Holding three wires for thread measurement

          I'm a tape guy. A strip of duct tape 3/4" wide about 1" longer than half the circumference. Lay two wires parallel cantered about 1 pitch apart. Apply the end of the tape to lap the ends of the wires by 1/2". Same on the other with the remaining wire. Carefully fold the tape over to capture the wires so no stickum shows.

          Bingo! The wires are firmly captured in their most usable position. Grab them by the tape with thumb and forefinger and by using the knuckle of your middle finger bring the single wire under the thread. Use the other hand holding the mike to guide the double wires over the work. Take your reading.

          If the wires are small and the thread large you may wish to tape the other ends of the wires to make a loosely fitting circle that goes around the work. If the tape is bright red they will never get lost if you drop them in the chips.

          If you get them oily be prepared for the tape stickum to slowly dissolve into goo.
          Last edited by Forrest Addy; 06-13-2008, 11:31 AM.

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          • #6
            I guess the thickness of the grease, clay, etc. in the root doesn't affect the measurement much?

            Forrest: I understand your tape method - I'll give it a try!
            Last edited by torchroadster; 06-13-2008, 11:15 AM.

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            • #7
              Get a small piece of soft foam, like the black electrostatic foam that chips are shipped in. Poke two of the thread wires into the foam along the bottom, and snug it up under the thread. The poke the remaining thread wire into the foam over the top, and use the micrometer jaws to clamp the three wires, held by the foam, together.
              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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              • #8
                Re: clay. You wouldn't put it on the threads; you'd stick the 3 wires into it, like with lazlo's foam idea (which sounds handier than modeling clay....)
                ----------
                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.
                Don't own anything you have to feed or paint. - Hood River Blackie

                Comment


                • #9
                  I had to do this not too long ago and I used a chunk of green floral foam from the craft department at Walmart. It's made to have stuff stuck into it. Works great and really cheap.
                  Stuart de Haro

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                  • #10
                    My machining textbook shows the wires being held with rubber bands.

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                    • #11
                      Just put a little grease on the thread top and bottom or all around if you want. Put the wires in the thread and measure bringing your mike up against the bottom wire first. Just like bobw53 said. The small amount of grease will not effect your measurement.

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                      • #12
                        We really need a sticky FAQ. This question comes up every couple of weeks. Same as "how to center square stock", ...
                        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                        • #13
                          Originally posted by lazlo
                          We really need a sticky FAQ. This question comes up every couple of weeks. Same as "how to center square stock", ...
                          With all due respect I've read this forum several times a day for the past 18 months and don't recall seeing this one before. Not that it shouldn't being a sticky - especially with the search feature not working well right now.

                          Thanks for all the ideas guys - I can't wait to try them out!

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                          • #14
                            Originally posted by torchroadster
                            With all due respect I've read this forum several times a day for the past 18 months and don't recall seeing this one before.
                            Holding thread wires w/only 2 hands

                            Thread Wires...

                            Originally posted by lazlo
                            Holding thread wires w/only 2 hands

                            In that thread we talked about grease, scotch tape, silly putty, sticky tack, and my favorite -- sticking the ends of the wires in the black electrostatic foam that chips are shipped in.

                            But Airhead's post #15 is a classic:

                            http://bbs.homeshopmachinist.net/sho...2&postcount=15
                            "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                            • #15
                              I use modeling clay or Silly putty. Being a mold maker Silly putty is standard fair and in all moldmakers boxes anyway.

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