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  • Hashed One Up

    Flushed with success over making a 1.75 x 20 tpi on my 1st attempt I decided to have a shot at working with internal threads. CCWKen was kind enough to send me a piece of metal with a 2.25 x 8 thread to make a mount for a monster 4-jaw I came up with, but it was just a bit tight.

    Coulda used that 2.25 x 8 tap the other guy came up with and if I was him I hang onto it! LOL!

    So I chucked it up looking to just chase the threads. Ground a 60 on a small piece of 5/16 HSS to fit in my 1" KDK boring bar. Got in time with the leadscrew. 8 tpi so no need for a threading dial. Ran it thru by hand a bit. Seemed OK to me.

    But here's the slap in the forehead part. For some reason I thought I could advance the cut by pulling the compound out. Well everything else was backwards! When that didn't work, still not realizing my mistake, I started pulling the cross back .005 a shot to get a cut and we went downhill from there. I hate ugly.

    Compounding the issue I was using my spin indexer as a test piece and it apparently has a slightly oversize shoulder on it at the end of the threaded area. At one point I had opened the threads up enough but when they ran into the shoulder stupid me kept thinking I needed to chase them some more!

    I hate sloppy too.

    Eventually the light bulb in my head turned on. I flipped the tool, starting working on the backside where the compound does what it's supposed to, and was able to produce a hugely oversized but decently cut thread on what was left of that poor piece of steel.

    Another lesson. Ken said he'd been stubbing his toe on that piece for a couple of years. Looks like it's my turn to do the same.

    SP

  • #2
    Let us know when you figure out how to quit making the odd booboo!
    Then we'll hire you to put on a course for us
    They say a good machinist has a pile of buggered parts under his bench.
    I'm starting to think of ways to build my bench higher...and maybe wider....yup...and a little longer too. Just planning ahead
    Yer not the Lone Ranger here I bet!
    Russ
    I have tools I don't even know I own...

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    • #3
      They're not "buggered parts." They're "Learning Experiences."
      ----------
      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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      • #4
        ...internal threading on the backside with an inverted tool is the way to do it...everything works just like you were cutting an external thread...compound setting...tool advancement with the compound...tool retraction with the cross slide...all the same...plus the chip falls away nicely...and maybe most of all...you can see what you are doing without mirrors or a pain in your neck...back...hip...etc!

        ...all that said...I have seen a machinist take a 3/4 course nut...bore it to 3/4 fine minor diameter...and thread it to fine thread by retracting the compound with it set as normal for external threading(chip is cut by the trailing edge of the tool). He was using someone else's lathe...and didn't want to mess with the other guy's compound setting.
        Last edited by Carl; 04-15-2007, 01:17 PM.
        THAT OLD GANG 'O MINE

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        • #5
          Well it's funny you mention this. I've figured out a way to make my threading "workflow" much smoother. I have my materials stockpiled on the left side of my lathe and my scrap bin on the right. My threading projects are now streamlined in that they go from material storage to lathe to scrap in one fluid motion. I'm thinking on eliminating the lathe as a means to really hurry things along

          Anyone else notice "scrap" is mostly "crap"?
          - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
          Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

          It is true, there is nothing free about freedom, don't be so quick to give it away.

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          • #6
            I have at work four perfectly machined pump shafts made from 1-1/4" 316 stainless and polished to a mirror finish.Sadly I cut righthand threads when the print called for left
            I just need one more tool,just one!

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            • #7
              I generally try to find something else to make from my, errr, "learning experiences". That's the only thing that keeps the pile from overwhelming my entire shop. See, the trick is, by the time you "learn" from it two or three times, the pieces are generally small enough to fit neatly into the shop vac hose and it saves on valuable space...
              Russ
              Master Floor Sweeper

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              • #8
                Originally posted by Your Old Dog
                Well it's funny you mention this. I've figured out a way to make my threading "workflow" much smoother. I have my materials stockpiled on the left side of my lathe and my scrap bin on the right. My threading projects are now streamlined in that they go from material storage to lathe to scrap in one fluid motion. I'm thinking on eliminating the lathe as a means to really hurry things along

                Anyone else notice "scrap" is mostly "crap"?
                YOD...LMAO! Lotta funny stuff on this thread! HSM...gotta stick together
                Russ
                I have tools I don't even know I own...

                Comment


                • #9
                  "Experience is what you get when you expected something else"
                  "Lay on ground-light fuse-get away"

                  Comment


                  • #10
                    Good judgement comes from experience. Experience comes from bad judgement.
                    Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                    ~Practitioner of the Electromechanical Arts~

                    Comment


                    • #11
                      Originally posted by pntrbl

                      So I chucked it up looking to just chase the threads. Ground a 60 on a small piece of 5/16 HSS to fit in my 1" KDK boring bar. Got in time with the leadscrew. 8 tpi so no need for a threading dial. Ran it thru by hand a bit. Seemed OK to me.

                      But here's the slap in the forehead part. For some reason I thought I could advance the cut by pulling the compound out. Well everything else was backwards! When that didn't work, still not realizing my mistake, I started pulling the cross back .005 a shot to get a cut and we went downhill from there. I hate ugly.
                      Er.....


                      If I have your setup visualized correctly, you DO advance the cut deeper by pulling the compound or crossfeed towards you(out) . At least you do when cutting on near side for RH threads in forward..... It helps to use the compound, and set it 29 deg to the LEFT so it advances into the leading side of the cut.

                      You ADVANCE the crossfeed (away from you) to DISENGAGE.

                      Now, if you mean that you could pull out for the next cut by coming towards you, well, OK that would not be the case.


                      I like reversing that, with the cutter on backside, because I can see what's up, and because then you start at the inside end, near the shoulder (if not a thru thread). And, NO it does not unscrew the chuck if you "set" it when installing. At least not for me.
                      1601

                      Keep eye on ball.
                      Hashim Khan

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                      • #12
                        Ah heck Bill! Well, maybe you can cut it to the next size up (2 3/8) and Ebay it. If nothing else, my toe is feeling much better.

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                        • #13
                          I never make scrap. Just pieces that are perfectly good stock for a smaller part.

                          Ever build two left wings for a model airplane?
                          Free software for calculating bolt circles and similar: Click Here

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