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cutting a 5C thread

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  • cutting a 5C thread

    I want to cut a 5C internal thread on my new drawbar I am making at my little retired engineers club at our local college.What info will the instructor need to help me to design/shape the cutter and any other info.I downloaded a pile of info about 5C collets it was not the right information to do this if you were cutting your own and needed to make a thread cutting tool what would be the necessery info you would need like thread height angles etc???Alistair
    Please excuse my typing as I have a form of parkinsons disease

  • #2
    Is this a standard 60 degree thread? If it is, an ordinary internal threading tool bit will do.

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    • #3
      When it comes to threading, 'standard' and 'ordinary' in Scotland are not (or at least, were not) the same as in the USA, IIRC.

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      • #4
        The OD of the threads on the collets is listed as 1.240 x 20TPI. For the ID just bore the end of the tube around .045" smaller (1.195) which should give around 75% thread. Just don't go nuts and shoot right for size. I have seen thread sizes on 5Cs vary somewhat. From 1.235 to 1.240 depending on the manufacture. Thread form is 60D UN. Make sure that the collet will screw into the tube all the way to the base of the 1.250" body diameter. And while your set-up knock out a couple of collet stops and if youd do it would be a good idea to make the collet body wrench for tightening them into the collet. I'll shoot some pics of mine at work and post them tommorow on p-bucket if you want
        Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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        • #5
          A 5-C collet has the same threads no matter where the collet happens to be located.

          You will need to cut a 1.240" 20tpi internal thread on the inside of your draw tube Alistair. You don’t need anything unusual, just a regular internal threading tool or a boring bar with a standard 60 آ° threading bit in it.

          I can look up the major/minor diameters for you if you need me to.

          Hey, Dأ©jأ  vu:

          http://bbs.homeshopmachinist.net//Fo...ML/007874.html

          [This message has been edited by Joel (edited 11-23-2004).]

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          • #6
            Yah Joel your right all 5C collets have the same thread its just that some of the maunufactures seem to trend a little towards the small side of the tolerance.
            Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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            • #7
              I wasn't referring to your post Spin.

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              • #8
                Joel,

                That's not my point. Saying 'standard' thread and 'ordinary' threading tool bit to a Scotsman can mean something different than it does to someone in the USA. Of course I didn't mean that the Scots make 5C collets differently than the USA manufacturers do.

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                • #9
                  we Scots doing everything back to front or is that front to back I never know which we even drive on the left
                  p.s Joel that would be great thanks. Alistair
                  Please excuse my typing as I have a form of parkinsons disease

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                  • #10
                    Alistair will go and have a look at my vast collection of old taps and see if i have a 5c one
                    if i do will send it up to you to use.
                    all the best..mark

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                    • #11
                      Nope dont have one .
                      But tell you what I have noticed .....may be wrong on this I dont know.
                      thread has the same pitch as an 8mm x 1.25 tap.
                      never tried this ....but you could grind away an 8mm x 1.25 tap just leaving one flute .......then use this suitably mounted as a chasser......you would have to get the hole in the draw bar to just under.....and keep chassing in and out with the new chasser whilst trying a 5c collet in there untill you are getting near.
                      just a stupid idea ..that I domt kinow will work
                      any thoughts anyone.
                      al;l the best....mark

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                      • #12
                        Thanks anyway Mark regards. Alistair
                        Please excuse my typing as I have a form of parkinsons disease

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                        • #13
                          A machinist showed me that trick. Just as you said grind three of the flutes away then leave 2-3 teeth on the remaining flute. Makes a great thread chaser or boring bar if you as I dont have a small enough boing bar for the job.
                          Coarse thread taps work best for fine thread bores. 1/4-20 unc makes a great bar for 7/16-20 unf etc
                          Greg

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                          • #14
                            1 1/4 - 20 tpi UN internal 2B:
                            Minor Diameter: 1.196 Min - 1.207 Max
                            Pitch Diameter: 1.2175 Min - 1.2236 Max
                            Major Diameter: 1.250

                            As has been pointed out, there is some variance in collet tolerance, so don't cut the threads too tight. Maybe measure your collets, find your biggest (pitch diameter) and make sure that it doesn’t fit too tightly before removing your part from the chuck.

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                            • #15
                              While we are on the subject of 5C collets there are probably a few tricks that the newbies should be shown if they start making their own tooling. When machining the threads on the collet stop body put a relief groove at the back of the threads (1.035" x 20TPI). Thr collet stop body should be made with an OD of 1.125". The reason for this is that if you don't have shoulder that the collet stop locks up on when you screw it in it will bottom out on the threads and you will get stuck tryoing to fix it after a while. I know I learned the hard way.. Notice the three stops in the following

                              http://img.photobucket.com/albums/v1...s/P1010290.jpg

                              The two with the shoulders work great and never give any problems. The one with out I won't even use anymore, Imjust keep it around for an example to show the kids of what not to do. Another necessary item is on of these

                              http://img.photobucket.com/albums/v1...s/P1010292.jpg

                              Works a lot better for tighteneing the collet stop into the collet than trying to hold the collet with channel locks.

                              But collet stops are not really accurate things for holding lengths as they will lose .003 for every .001 difference in diameter. If you absolutely need to hold accurate lenghts and have a shoulder you can work off of these work great. Not my idea I copied them from the ones Hardinge sells. The disk is counterbored on the back side to fitt over the OD of the collet. The part passes through the disc and as the collet is closed it withdrawls into the spindle pulling the part along with it. When the shoulder on the part hits the disk it stops while the collet continues to get pulled in. When the collet is gripping the part it is also pulling the part against the disk forcing the disk against the front face of the spindle. This also acts to increase the rigidity of the set-up in the machine always a good thing. The larger cylinder is one of the carriers that Hardinge sells for use with these but one can get by with out the carrier in a hiome shop. Their hard copy catalog for collets used to have a great section on fixturing and collet set-ups but I don't know ithe on line catalogs do

                              http://img.photobucket.com/albums/v1...s/P1010296.jpg
                              Forty plus years and I still have ten toes, ten fingers and both eyes. I must be doing something right.

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