Thread: Threadmilling

  1. #1
    Hi guys,

    How would i go about threading a 1" dia hole 7mm down with a NPT Thread..

    Ive looked at getting a tap and die set but there very very exspensive..

    So ive started to look at Threadmills, none tapered.

    I will be trying this on Alli on my sherline mill

    Cheers for any help you guys can provide!


  2. #2
    Taps and dies are cheap in carbon steel, suggest you search more.

    Thread mills are hideously expensive but you can cut any taper you like.
    If the thread is only 7mm deep you aren't going to get a taper seal anyway, the PTFE tape will laugh at you

  3. #3

    Im wanting to replace the brass valve for a alli manifold.

    What would you suggest is the best way of doing this.

    the steel but you see i will be keeping.

  4. #4
    Jay's Avatar
    Lives in Chesterfield, United Kingdom. Last Activity: 07-11-2016 Has been a member for 9-10 years. Has a total post count of 19.
    To cut an NPT thread using a thread mill you need a proper tapered thread mill or you wont be able to form the taper.
    What your proposing is a BSP thread so are you sure its NPT?
    Because your only wanting to cut 7mm deep you may end up chopping your tap down to get the right form so other than that the thread mill is your only option at the depth your working to bud.

  5. #5
    You have no need for a "threadmiil", a single point cutter will be much more in-scale with the sherline and non-production environment.

    The taper is a pain to code, there are lots of low cost tools and wizards available to do the calculations if you don't have a CAM solution most of them have demo/trial modes. Search taper spiral gcode.

    edit: trial not trail

  6. #6
    iv used taps before now, grind two of the flutes off and grind some clearence behind the cutting edges and your away

    they do not work quite as well as a threadmill but can get you out of splashing good money for a one off

    its probably worth shortening the tap so you have just enough deapth and use plenty of passes

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