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Work holding, threaded rod

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  • Work holding, threaded rod

    A few days back I recommended that Samuel make a collet to hold some drill rod in the spindle. Today I needed to hold some precision acme threaded lead screw stock so I could turn the ends for bearings. Of course, it is important that the bearing and the thread be concentric without damaging the threads while turning.

    So, I made a collet to hold the work in the 4 jaw. It is aluminum so it won't mar the threads. I left a sholder on the collet so it can't slide into the chuck in use. It is bored and then slit with the bandsaw.



    It is set in the 4 jaw with the work in place. I screwed on a pair of acme nuts back to back and indicated to them. It was simple to adjust to dead on concentric. Indicating to the threads agreed as well.



    The left end of the rod is supported in the left side of the spindle with another acme nut. I machined it to 3/4" to match my spindle bore as I won't be using the as supplied threads anyway. Since the bore is slightly over 3/4" a wrap of tape makes a perfect fit.



    Work finished, dead on concentric to the threads.



    Free software for calculating bolt circles and similar: Click Here

  • #2
    Nice work as always!
    Techno-Anarchist

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    • #3
      Darn, you can do some nice work Evan. I thought you just spent all your time lounging naked in that big tall chair you built.
      Michael

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      • #4
        Cool nice job, you did some nice straight cuts with the bandsaw too.

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        • #5
          Very nice work, Evan. Acme rod is nice to chuck that way.
          When it comes to standard threaded rod I like to sand the top of the threads a bit to remove the worst of the burrs before chucking it. Seems to run a little truer that way.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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          • #6
            Yep, nice work.. I also like the bandsaw work. Did you make a jig of some sorts? I could never cut those nice slits freehand. JRouche
            My old yahoo group. Bridgeport Mill Group

            https://groups.yahoo.com/neo/groups/...port_mill/info

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            • #7
              No jig for the bandsaw cuts. I cut a nice long dowel that was a press fit and used that to hold it while cutting against a fence. Makes it easier to hold straight.
              Free software for calculating bolt circles and similar: Click Here

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              • #8
                If you did those slits on a bandsaw, I definitely need to get a better bandsaw!
                :-)

                Paul F.

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                • #9
                  Evan,
                  Am I correct in thinking that with that type of collet you would get a point load at the front? Does this not matter since you machined it so close to the diameter of the Acme rod? When setting up acme rod in the lathe, why not engage the half nuts while indicating it?

                  still learning

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                  • #10
                    The slots in the collet are about 3/4" longer than the jaws of the chuck. The wall thickness of the collet is about 1/8". The aluminum is flexible enough that it will compress to grip the work along the length of the jaws because of the length of the slots.

                    I don't understand your reference to the half nuts.
                    Free software for calculating bolt circles and similar: Click Here

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                    • #11
                      nice job evan, I am working on my " collet" set up right now. maybe done in a week or so. looks great and thanks again.


                      Samuel

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                      • #12
                        Evan,
                        Thank you for the reply. That makes sense with the thin wall. I'll have to go find your other post you referenced earlier.

                        Regarding the half-nuts. Let's say you wanted to dial some Acme rod in real close. Take a DTI and mount it on the compound. Set your change gears to the TPI. Adjust the compound so that the DTI is indicating the crest of the thread. Engage the half-nuts. Then the DTI will stay on the crest while you are centering the chuck.

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                        • #13
                          Since you weren't going to use the threads on the outside of the acme nuts, it seems like you could have turned down another nut to go in the chuck to hold the rod, then use the third acme nut as a jam nut to keep the rod from turning.

                          That would eliminate the need for the collet, wouldn't it?

                          Would the rod self-center if the jam-nut was loosened/tightened to reposition the rod?

                          How much of the rod did you have sticking out of the collet when you did the turning?

                          Or, was the outer end of the rod supported by a live center in the tailstock? Looks like it has been center-drilled.

                          Thanks for the tip about using a dowel to get the straight cuts on the bandsaw. And I like david_r's idea about engaging the half-nuts while using the DTI to indicate on the threads.

                          And thanks for sharing another example of your fine work.

                          Roger



                          Any products mentioned in my posts have been endorsed by their manufacturer.

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                          • #14
                            Thanks for the post Evan. Always enjoy looking at your projects! The hole in the collett has a pretty nice finish. Did you finish up with a reamer after the bandsaw work?
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                            • #15
                              Nice work.But I have yet to see anything you do that wasnt high quality,even jigs, fixtures,or one time use items.

                              Do they still make button indicators like that? I have been kinda looking for one.

                              ------------------
                              The tame Wolf !

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