Announcement

Collapse
No announcement yet.

Versatile thread milling cutter

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Versatile thread milling cutter

    Click image for larger version  Name:	C509BFBF-1409-48E6-8A57-0E5150367303.jpeg Views:	4 Size:	2.14 MB ID:	1942192 I built a milling attachment for my lathe One of the reasons for doing this was to do some internal thread milling on various jobs. I decided that I could use a regular boring bar that used laydown threading inserts. I bought a 5/8 bar and there are a number of different inserts available for this bar. I was really happy to find that I could find a full profile 20 threads per inch internal insert. Here is a picture of the set up it worked very well. I prepared the part by boring the thread I D how about .005 under size. I ran the spindle in reverse and Fed away from the Chuck I have a variable frequency drive on my lathe spindle.I can slow it all the way down to 0 rpms . It worked very well here are a few pictures.Edwin Dirnbeck ​​ image widget
    Attached Files
    Last edited by Edwin Dirnbeck; 05-09-2021, 03:51 PM.

  • #2
    What is the minimum diameter that your present setup can manage?

    Comment


    • #3
      Originally posted by old mart View Post
      What is the minimum diameter that your present setup can manage?
      When you rotate the tool it will fit inside a .75 hole. So, whatever INTERNAL THREAD that you are making must have a minor diameter(tap drill size) LARGER than .750.This tooll will also cut most common EXTERNAL THREADS. Another advantage of thread milling is that you can make good INTERNAL threads all the way to the bottom of a flat bottom hole.You can in allso make good EXTERNALl threads all the way up against a shoulder. Edwin Dirnbeck
      Last edited by Edwin Dirnbeck; 05-09-2021, 08:11 PM.

      Comment


      • #4
        how is the threading bar driven? How is it indexed to the carriage movement? Does the spindle turn at the same time? I'm very curious

        Comment


        • #5
          Click image for larger version

Name:	D4D04B50-EFF5-41A7-9FE7-C1D7E5DB2D2D.jpeg
Views:	373
Size:	2.97 MB
ID:	1942241
          Originally posted by mattthemuppet View Post
          how is the threading bar driven? How is it indexed to the carriage movement? Does the spindle turn at the same time? I'm very curious
          In reply number 3 of this topic ,I posted a picture of my electric milling head that I made . A The threading bar spins about 2000 rpm. B Move the threading bar to the bottom of the hole. C Turn the lathe on in REVERSE about 4 rpm. D Feed larger on the x,the tool cuts a v shaped groove at bottom of the hole. E Engage your threading half nut just as if you are cutting an internal thread away from the headstock. F The tool cuts the entire thread in one pass I have a VARIABLE FREQUENCY DRIVE ON LY LATHE . i CAN TURN MY RPM DOWN TO ZERO. On hard material ,I take another spring pass. Edwin Dirnbeck
          Last edited by Edwin Dirnbeck; 05-09-2021, 10:49 PM.

          Comment


          • #6
            I am totally impressed. Might even have to build one !

            -Doozer
            DZER

            Comment


            • #7
              Originally posted by Doozer View Post
              I am totally impressed. Might even have to build one !

              -Doozer
              Thank you. I am planning to make a much better you tube video. I will show more capabilities of this tool.One thing that is not obvious ,is the ability to run in reverse direction by rotating the motor assembly 180 degrees.This just takes a minute.I didnt try to electricaly reverse the motor because of the built in speed sensing devise. I will also show some construction details with things that I would change. Edwin Dirnbeck

              Comment


              • #8
                Nice.... I like it.

                A question: Why did you go with the chain over a belt drive? Is it also used as a positioner?
                2730

                Keep eye on ball.
                Hashim Khan


                It's just a box of rain, I don't know who put it there.

                Comment


                • #9
                  I assume you are cutting the entire thread in one pass. I cant understand how different diameters of thread are accomodated.

                  Comment


                  • #10
                    old mart,
                    As I understand it, the cutter's axis is offset from the work piece axis so only one area is being cut. If you google internal thread milling it's the same process only with a different type of cutter.

                    ETA: This animation shows how it works: https://www.youtube.com/watch?v=i4EfNkPJreo
                    Last edited by Galaxie; 05-10-2021, 12:21 PM.
                    Location: Northern WI

                    Comment


                    • #11
                      Originally posted by old mart View Post
                      I assume you are cutting the entire thread in one pass. I cant understand how different diameters of thread are accomodated.
                      I assume that he just moves the cross slide out a little. Just like with a regular tool. He's replaced the usual static tool with this spinning boring bar to avoid the need to make many multiple passes. A nice option for production work.

                      The neat thing about using a full profile insert is also that if the bored ID is left a few thou small the full profile feature would dress off the peaks to leave a nice burr free profile.

                      Nice work there Edwin
                      Chilliwack BC, Canada

                      Comment


                      • #12
                        Click image for larger version

Name:	F8D897FB-2E68-43BD-B989-68966A16C055.jpeg
Views:	204
Size:	2.76 MB
ID:	1942339
                        Originally posted by J Tiers View Post
                        Nice.... I like it.

                        A question: Why did you go with the chain over a belt drive? Is it also used as a positioner?
                        A chain is smaller ,stronger and thinner and sprockets are available in many sizes in a day from Mcmaster.I wanted to keep the same vertical C/L as my headstock..From the top of my compound to the C/L,is onlly 1.440,so everything must be as compact as possible.The 5c draw tube must fit thru the sprocket ID,so things get pretty thin when you try to fit it all together.A flat belt such as on a dumore tool post grinder would be nice ,but I dont think that it would be strong enough. A cog belt would work,but I didnt want to fool with unknown sourcing problems. Now that I see how well that this works ,I might revise it and use a cog belt.The 5c head will hold a drill chuck for center drilling and drilling bolt circle patterns. Edwin Dirnbeck
                        Attached Files
                        Last edited by Edwin Dirnbeck; 05-10-2021, 06:53 PM.

                        Comment


                        • #13
                          OK thanks.... makes sense.
                          2730

                          Keep eye on ball.
                          Hashim Khan


                          It's just a box of rain, I don't know who put it there.

                          Comment


                          • #14
                            That looks like one heck of a tool. I want one!

                            Thanks for posting about it.
                            Paul A.
                            SE Texas

                            And if you look REAL close at an analog signal,
                            You will find that it has discrete steps.

                            Comment


                            • #15
                              Is the tool axis set to the helix angle of the thread when you cut the threads? Otherwise you'd get some error on the included angle in the cut threads. Probably not that much on a finer pitch, but might be pretty significant on coarser pitch.

                              Comment

                              Working...
                              X