1/4 npt internal thread

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Thread: 1/4 npt internal thread

  1. #1
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    Default 1/4 npt internal thread

    Hi, I have a 1/2 npt and 1/4 npt internal threads I have to machine (screw cut) on a fanuc lathe, can't tap as in very hard steel. I have a 08 14 NPT insert and 06 18 NPT for the 1/4 thread. Problem is I know it's a 1/16 taper but don't know the start dia or the thread length or what size to bore the taper. Do have a engineers hand book that's only any good for the tapping drill size for both these threads, any help would be great.

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  2. #2
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    Default

    Also I have step gauges and program in metric using a G76 for the thread



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    Is this what you are looking for?

    Attached Thumbnails Attached Thumbnails 1/4 npt internal thread-pipe_threads_001-jpg   1/4 npt internal thread-pipe_threads_002-jpg  


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    Have seen this chart yes Thanks



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    Is the problem in that you do not know how to read the information off of the charts?



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    Yep found it hard to make sence of the chart, I have the job on the machine and need to crack on in the morning. Was just looking for a quick easy way out to get the figures and complete the job



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    For 1/4-18 - Starting Diameter is 0.49163.

    For 1/2-14 - Starting Diameter is 0.77843.

    Does that help?



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1/4 npt internal thread

1/4 npt internal thread