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Thread: 8-32 tap for long tapped holes

  1. #1
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    8-32 tap for long tapped holes

    I am looking for a 8-32 tap to create threads in 1" long hole. Not a hole 1" tapped at the bottom, but a 1" piece with a hole tapped all the way through it. What do I need to google to get a 8-32 tap capable of producing 1" of threads? Searching for '8-32 extended tap' results in the getting really long taps that will still only produce 3/4" of threads.
    Last edited by Anthony Whitesell; 03-05-2022 at 4:47 PM.

  2. #2
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    A regular tap won't have any trouble with 1" of threads. It just keeps cutting as it goes. The only limit is hitting the handle. If it's not going past the taper, just get a set of three taps including a bottoming tap, even though there is no bottom.
    Last edited by Tom M King; 03-05-2022 at 6:02 PM.

  3. #3
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    I have ground the shank down on some taps so they can pass through the work piece.

    Screen Shot 2022-03-05 at 5.13.14 PM.png
    Last edited by Maurice Mcmurry; 03-05-2022 at 6:18 PM.
    Best Regards, Maurice

  4. #4
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    Quote Originally Posted by Tom M King View Post
    A regular tap won't have any trouble with 1" of threads. It just keeps cutting as it goes. The only limit is hitting the handle. If it's not going past the taper, just get a set of three taps including a bottoming tap, even though there is no bottom.
    Regular 8-32 taps (or at least the plug taps I have) have a shaft that is the same OD as the thread cutting portion. Once the thread cutting portion reaches the part it will not feed any further. I have even found a few taps where the shaft is a larger OD than the thread cutting portion. Once you reach 1/4-20 (at least in my set and pictures online) the shaft is a smaller OD than the thread cutting portion.

  5. #5
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    Thanks. I never noticed that. The last threads I had to cut were 1" with a bottom. I would probably try grinding the shank down, and being very careful while cutting the threads.
    Attached Images Attached Images

  6. #6
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    Google spiral pointed gun tap 8-32 Pully & Long

    https://www.msdiscounttool.com/catal...xoC2CsQAvD_BwE
    Last edited by Tom M King; 03-05-2022 at 6:36 PM.

  7. #7
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    Quote Originally Posted by Tom M King View Post
    Thanks. I never noticed that. The last threads I had to cut were 1" with a bottom. I would probably try grinding the shank down, and being very careful while cutting the threads.
    Neither did I, until the tap refused to turn.

    I will probably go that route. I will use a un-modified tap for as much as it can, then switch to the ground shank tap to finish the hole.

  8. #8
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    1" deep #8-32 seem entirely unnecessary. I'd counterbore one side and use a standard tap.
    "Anything seems possible when you don't know what you're doing."

  9. #9
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    Quote Originally Posted by andy bessette View Post
    1" deep #8-32 seem entirely unnecessary. I'd counterbore one side and use a standard tap.
    The 1" width is necessary, or it would be 3/4" and use a standard tap.

  10. #10
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    Quote Originally Posted by Anthony Whitesell View Post
    The 1" width is necessary, or it would be 3/4" and use a standard tap.
    Why do you need 32 threads engaged?
    "Anything seems possible when you don't know what you're doing."

  11. #11
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    Quote Originally Posted by andy bessette View Post
    Why do you need 32 threads engaged?
    It's not the 32 threads that is required. It is the 1" width due to the rotational load placed on the piece. Technically the part could be a Y or yoke shape, but that would require a tap with more than 1" of cutting area to keep the threads of the second half in time with the first half. That would require a tap with more than 1" of cutting area which we did not find readily and/or affordably. I'm not designing the part here. I am just looking for a tap to complete the job. I have ordered some taps that have a taper after the cutting area to help guide me when reducing the shaft diameter. Do you have a source for one that is premade with a reduced shaft diameter or cutting length in the 1 1/4" neightborhood?

  12. #12
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    MSC Industrial Supply and Grainger have several options that will tap through 1 inch.

    https://www.mscdirect.com/product/details/08693582https://www.mscdirect.com/product/details/08693582https://www.mscdirect.com/product/details/08693
    Attachment 475263 Screen Shot 2022-03-06 at 5.57.17 AM.png
    Last edited by Maurice Mcmurry; 03-06-2022 at 7:14 AM. Reason: + Grainger
    Best Regards, Maurice

  13. #13
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    Quote Originally Posted by Maurice Mcmurry View Post
    MSC Industrial Supply and Grainger have several options that will tap through 1 inch.

    https://www.mscdirect.com/product/details/08693582https://www.mscdirect.com/product/details/08693582https://www.mscdirect.com/product/details/08693
    Attachment 475263 Screen Shot 2022-03-06 at 5.57.17 AM.png
    Which tap is that from Grainger? The one had work purchase I was going to "borrow" that had a similar picture, didn't arrive looking like the picture.
    Last edited by Anthony Whitesell; 03-06-2022 at 7:35 AM.

  14. #14
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    Both previously pictured are from MSC

    #8-32 UNC Bottoming Thread Forming Tap


    Cobalt, TiCN Finish, 2-1/8" OAL, 3/4" Thread Length, Right Hand Thread, H4 Thread Limit, Series HY-PRO NRT

    MSC Part #: 08693582
    Mfr Part #: 1400114008


    from Grainger
    Screen Shot 2022-03-06 at 7.15.23 AM.png
    Last edited by Maurice Mcmurry; 03-06-2022 at 8:21 AM.
    Best Regards, Maurice

  15. #15
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    Anthony, did you see that link in post #6? I wonder if that picture is an 8-32.

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