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Thread: Pipe threads on a manifold block?

  1. #1
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    Default Pipe threads on a manifold block?

    I need to make two manifold blocks for the air supply for my sheep release pen. I have never done anything but male pipe threads with a pipe threading machine.

    So I need to drill a hole and then do I just tap with a pipe thread tap the same as with a normal straight tap? I have to buy the tap. It will be for 3/8 fittings.
    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

  2. #2
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    Just a normal BSP tap, or if stuck weld a couple of sockets on, works in a pinch
    Regards
    Mark

  3. #3
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    Pretty much. Buy a GOOD tap. It makes a tremendous difference, especially with pipe threads.

    You can step-drill the holes if you want to be finicky, to help account for the taper, but getting the depths correct for the different diameters may be more trouble than it's worth.
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  4. #4
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    Pro tip: buy matching tap and fittings ��
    Lota of cheapo import stuff here in europe is NPT but more standard is BSP. If mixed wont fit more than one turn..

    I'd choose non-tapered bspp or "G- thread" and glue em with pipe sealing compound.

  5. #5
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    Quote Originally Posted by SGW View Post
    Pretty much. Buy a GOOD tap. It makes a tremendous difference, especially with pipe threads.

    You can step-drill the holes if you want to be finicky, to help account for the taper, but getting the depths correct for the different diameters may be more trouble than it's worth.
    Quote Originally Posted by MattiJ View Post
    Pro tip: buy matching tap and fittings ��
    Lota of cheapo import stuff here in europe is NPT but more standard is BSP. If mixed wont fit more than one turn..

    I'd choose non-tapered bspp or "G- thread" and glue em with pipe sealing compound.
    Yes, first make sure which thread you need BSP (British Standard Pipe) or NPT (National Pipe Tapered)

    And then a quality HSS tap, no Harbor Freight carbon steel or European equivalent.

    Also, some cutting oil, if these holes are in Aluminum, get the fluid made specifically for aluminum.

    As for being finicky, you would ream the holes with a matching pipe tapered reamer before tapping, the other extreme would be eliminating the taper by using the BSPP (British Standard Pipe Parallel) tap. Not quite sure why a person would want to use straight threads, you can use thread sealant on tapered threads as well.

    Dave

  6. #6
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    AFAIK, for BSPT (British Standard Pipe Tapered), only the male part is tapered, the female is parallel. NPT I don't know.
    Last edited by Benta; 02-14-2017 at 07:59 AM.

  7. #7
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    Quote Originally Posted by Benta View Post
    AFAIK, for BSPT (British Standard Pipe Tapered), only the male part is tapered, the female is parallel. NPT I don't know.
    NPT and NPTF both have female tapers.

  8. #8
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    NPT both male and female are tapered.

    Pete
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  9. #9

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    They do make a tapered reamer for preparing holes for pipe taping, but I don't know I have ever seen one used.
    Remember to watch the drill sizing. A standard 3/8 tape would be 5/16, but with a taper it may be different so watch for that.

  10. #10
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    I usually didn't use a reamer for 1/8 or 1/4 NPT pipe taps, but did for 3/8. Made it much easier to tap and there was less tearing of the threads = better seal in the end. For reference, this was in tool steels; aluminum would be easy enough without the reamer.
    George

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