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Radiator Vent Hole Stripped

Steamhead (in transit)
Steamhead (in transit) Member Posts: 6,688
in THE MAIN WALL
Gordo is the best partner I could have, that doesn't mean anything?? ;-)

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  • Al_23
    Al_23 Member Posts: 4
    Radiator vent hole stripped

    Changing out the vents on the radiators one was forund to be pretty much wasted. The old vent came out and I chased the threads with a Vent tool I purchased from my local hardware store. The tool went in OK but I could not get the vent to screw in. With a mirror and flashlight I examed the hole and the treads were gone Just smooth metal. The local hardward guy recommended J-B weld putting a thin layer in letting it dry the re tap the hole.
    Are there any other options
    Thanks in Advance
  • Ken_40
    Ken_40 Member Posts: 1,310
    Two options:

    1) Buy a real 1/8" NPT tap from a good hardware or industrial hardware "store." Or,

    2) Buy a 1/4" NPT tap, correctly sized drill-bit (the correct size drill-bit can frequently be noted on the tap, e.g., "use a 13/32" bit pilot for this tap." Note! 13/32" is NOT the correct bit to use - if I felt like running downstairs to look in my machinist's handbook - I could tell you with certainty what size bit to use...

    And a 1/8" X 1/4" "flush-bushing"

    After retapping/"chasing" the 1/8" NPT thread, going as "lightly" as possible to get a decent thread, but not so far in as to render the vent "shouldering" before becoming snug (use no dope on this joint. Dry fit).

    If the thread is too large to properly "hold" the vent in place, you will have to drill and tap it to the next size up - or become a wizard at installing a "heli-coil" in pipe thread, something that is about as common as hen's teeth; and, then bush back down to the reauired 1/8" NPT.

    Voila!
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Stripped vent hole

    7/16" is the drill size for 1/4" npt.

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  • Ken_40
    Ken_40 Member Posts: 1,310
    Regardless of what

    Frank says about you; you're still a good kid (;-o)

    You know that one off the top of your head? Or did you go down and look at my machinist's handbook? If you did, I never heard you come in, or go out...
  • brucewo1b
    brucewo1b Member Posts: 638
    Question

    is that 7/16 or more like 7/32, I would think 7/16 for a 1/4 inch tap would be rather loose??
  • Ken_40
    Ken_40 Member Posts: 1,310
    Remember,

    A 1/4" pipe is 1/4 inch I.D.!

    The threads are much larger than the inside of the pipe, probably closer to 1/2" - which would make a 7/16" hole about right...
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    Drill sizes

    Frank will tell you that my memory for numbers is way below average...and that's confirmed by testing at the Johnson-O'Conner Institute. But those sizes I do remember: 9/16" drill for 3/8" npt, and a 1/8" npt hole is brought to you by the letter "R"...drill bit size. I used to think is was "Q", but not any more. 1/2"npt can be fudged by a 3/4" drill size (a bit large). The other sizes I'd have to look up.

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  • brucewo1b
    brucewo1b Member Posts: 638
    Ken your probably right

    just going by guess here at the moment too
  • brucewo1b
    brucewo1b Member Posts: 638
    Not saying your wrong Gordo

    I was going by my guess too, can't remember it all
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    I was replying

    to Ken's mild gibe, and certainly did not take umbrage at your question of drill sizes. Sorry if it came out like that.

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  • Al_23
    Al_23 Member Posts: 4
    Vent hole stripped

    Ken
    Thanks ran the tap in and out and got the new vent installed all is OK Thanks
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 18,399


    I know your talking pipe threads but I'll fillin the blanks for machine screws:

    6-32 #36 drill
    8-32 #29
    10-24 #25
    10-32 #21
    1/4-20 #7
    5/16 nc 1/4"
    3/8-16 5/16
    1/2" 27/64

    If you only cary those drill bits your in pretty good shape. #36 taps for the #6 screw, #29 is 8 screw tap and body size hole for the #6 screw, 21 & 25 for the #10 taps and body size for the #8, #7 body size for the 10s and taps 1/4-20, 1/4" taps 5/16 and body size for the 1/4", 5/16 taps 3/8" and body size for 5/16.

    I respect a mechanic who uses the right stuff. Having seen people jamb sheet metal screws or the wrong screw in a tapped hole drives me nuts
  • Ken_40
    Ken_40 Member Posts: 1,310
    Al,

    Sometimes the bear east you.

    Today, you ate the bear.

    Thanks for letting us know all's well.
This discussion has been closed.

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