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  1. #1
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    taps for fittings and screws

    lets say i would use these for my waterblock fittings

    i would use a 1/4" npt tap right? but i notice there are 1/4"- 18 and 1/4"-20 taps. would it matter which one i would use?

    and

    Machine screw sizes:4-40, 6-32, 8-32, 10-24, 10-32 and 12-24
    what do those numbers mean?

    thanks for the help

  2. #2
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    ok and lets say i will top it with something clear..ok ok dont get all ****y on me but if i were, which would be the strongest like not prone to cracking EASILY lexan, poly, or luctite

    and i know sometimes the moving of barbs will crack a top...so how should hoses be properly pulled off the barbs? should i put some sort of lube on the fittings so it will be easier to pull off?

    thnx again guys

  3. #3
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    For machine screws, the number is the size, smaller numbers are smaller diameters, 4 is about 0.114" dia, 6 is around 0.136", 8 is like 0.166" ,etc.. then you hit 1/4" and from there they use the actual diameter for the sizing. The second number is the threads per inch. So 4-40 is #4 screw diameter with 40 threads per inch. You just match them up to the right nut so it will fit, and you choose the screw diameter size so it fits in the right hole. #6 is typical for the mounting holes in the fans

    Lexan is a brand name for polycarbonate. Lucite is weaker I believe, it's what they make clear paperweights and awards and stuff like that with. Polycarb is for safety glass like bulletproof windows.

  4. #4
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    Oh yeah, the tap you use needs to match the thread on the fittings. Though I don't expect much difference between 18 and 20 threads per inch, but probably there is a more commonly used one around here. For thick or "soft" material you usually use lower threads per inch. For example, wood screws have a very coarse thread density.

  5. #5
    The Half Asleep Member Stedeman's Avatar
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    the thread is not so much about the material you use but the grade of connection

  6. #6
    Underwater Senior Member
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    Re: taps for fittings and screws

    Originally posted by pokpok
    I would use a 1/4" npt tap right? but i notice there are 1/4"- 18 and 1/4"-20 taps. would it matter which one i would use?
    1/4-20 NPT Pipe Tap.
    Last edited by Diggrr; 03-06-03 at 05:07 AM.

  7. #7
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    for waterblocks whats the suggested size for the screws?

  8. #8
    Underwater Senior Member
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    #8-32 threads per inch are what I use. Good adjustment, and the fine thread helps keep them from wandering loose. Some boards may not have holes large enough for screws any bigger diameter than #8. It's also an easy size to find the other parts for it, like nuts and stuff.

    Oh, and sorry for my bad manners...Welcome to the forums!

  9. #9
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    thanks

    for 8-32 screw what size drill and tap would it need?

    and for 1/4" - 20 tap its recommended that i use a 7/16" bit, and this is fine correct?

  10. #10
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    for a 8-32 you need a #29 drill (.1360") for the tap drill
    for the tap an 8-32.
    clearance holes for 8-32 are between #18 (.1695") - #16 (.1770)

    for a 1/4-20, the tap drill is a #7 (.201)
    1/4-20 tap
    clearance holes between letter F (.257) - letter H (.266)

    and for pipe taps
    1/4 npt a 7/16" drill for tapping
    Last edited by Zordan; 03-06-03 at 05:27 PM.

  11. #11
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    Originally posted by Zordan
    for a 8-32 you need a #29 drill (.1360") for the tap drill
    for the tap an 8-32.
    clearance holes for 8-32 are between #18 (.1695") - #16 (.1770)

    for a 1/4-20, the tap drill is a #7 (.201)
    1/4-20 tap
    clearance holes between letter F (.257) - letter H (.266)

    and for pipe taps
    1/4 npt a 7/16" drill for tapping
    "for the tap drill for the tap an 8-32."

    is a "tap drill" another name for the thing that makes the threads in. if not whats the difference between a tap drill and a drill? lol im all confused now

    sorry for the questions i just want to make sure i know what im buying

  12. #12
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    The tap drill is the drill bit that you use to make the hole before you tap it.

    The hole needs to be smaller than the finished thread size so that the tap can cut out some metal to form the threads.

    Hope this helps.

  13. #13
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    ok if i were to tap something would this be the order

    drill>tap drill>then tap?

    i stopped by home depot a while ago just so see the taps sizes, i didnt buy though. i noticed that the taps were sold along with the bits...are these the tap drills?

    so

    #1 for a 1/4-20, the tap drill is a #7 (.201)
    1/4-20 tap
    clearance holes between letter F (.257) - letter H (.266)


    #2
    and for pipe taps
    1/4 npt a 7/16" drill for tapping


    which one would i use for these

    those are suitable for waterblock tops though right ?

  14. #14
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    The order is:

    Drill hole with Tap Drill (Its just a regular drill bit), then tap.

    For those hose barbs, you will need to drill a 7/16' hole, and tap the hole using a 1/4 NPT tap.

    The NPT stands for National Pipe Thread.

    For the smaller holes (to hold the two block halves together) I would try to find a thread forming tap.

    This tap rolls the threads instead of cutting them. They work so much better in gummy metals (like copper), and will help you to not break the tap off in the metal.

    For a #6 thread forming tap, you should drill an 1/8 hole.

    Hope this helps.

  15. #15
    Hey! I showered! Senior JFettig's Avatar
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    eek
    this is messed, 1/4-20 is 1/4inch screw, 1/4npt is 1/2-18 with a 60some degree taper, much much different
    I use 4-40 and 6-32 screws and taps, I have thread forming taps wich use larger holes but make threads TONS easier, and they are pretty much as good. they push the material rather than cut it.
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  16. #16
    Hey! I showered! Senior JFettig's Avatar
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    also, when your tapping a 1/4NPT thread, you cannot go all the way thru, you only go as far as needed for the barb, as you tap deeper, the barb will screw in farther....
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  17. #17
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    Good call on that on J.

    I forgot to say that the NPT threads are tapered (So they will seal).

    You should run the tap into the top until the bottom of the tap just peeks out of the bottom of the hole.

    If you run the tap into the hole too far, the barb won't seal, and you will have a leaky top (bummer )

    Make sure that you are running the taps into the block squarely, otherwise your barbs will stick out at funny angles.

    Have fun.

  18. #18
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    alright thanks for the the help guys i really apreciate it

  19. #19
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    Originally posted by JFettig
    eek
    this is messed, 1/4-20 is 1/4inch screw, 1/4npt is 1/2-18 with a 60some degree taper, much much different
    I use 4-40 and 6-32 screws and taps, I have thread forming taps wich use larger holes but make threads TONS easier, and they are pretty much as good. they push the material rather than cut it.
    what do you use to seal your blocks? Should you tap all the way through if you wanted to use screws to seal rather than nuts and bolts without threads?

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