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    Default 1/4 NTP THRU 304 BAR

    The last time I had this job I went thru 3 taps (broken teeth) on ten parts.
    I tried drilling oversize, big chamfers, down to 15 SFM. Nothing seemed to work.

    I just got them again. HELP
    I don't want to do them by hand.

    HAAS VF3



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    Member extanker59's Avatar
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    Default Re: 1/4 NTP THRU 304 BAR

    Years ago I ran 1/4" NPT in 303 stainless. I used a tapered mill to get the correct taper before tapping. I also had a M00 to apply thick tapping fluid before each hole. I don't remember going through taps but it was years ago.



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    Default Re: 1/4 NTP THRU 304 BAR

    What is the material? What kind of holes? What size and depth of holes? What brand and style of taps were you using? What speed were you tapping at?

    Lee


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    Default Re: 1/4 NTP THRU 304 BAR

    REGAL BELOIT, SOME "WHO KNOWS WHAT" 5/16 304 BAR
    The last time I had this job I went thru 3 taps (broken teeth) on ten parts.
    I tried drilling oversize, big chamfers, down to 15 SFM. Nothing seemed to work.



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    Default Re: 1/4 NTP THRU 304 BAR

    CUTTING LUBE
    RIGID EXTREME PERFORMANCE THREAD LUBE



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    Default Re: 1/4 NTP THRU 304 BAR

    I assume you mean NPT. I think you need to have the perfect recipe of hole size, speed and depth to pull this off in a machine without breaking taps. I don't think I have ever seen a machine tap for an NPT thread. I am sure they make them, but I would not want to see the cost.
    I did see these at McMaster Carr, but they are still intended for hand tapping.
    https://www.mcmaster.com/2663a43

    Not cheap either.

    Lee


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    Default Re: 1/4 NTP THRU 304 BAR

    304 is a PITA to work with. Maybe a thread forming tap would work? http://balax.com/sites/default/files...-Pipe-Taps.pdf

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: 1/4 NTP THRU 304 BAR

    Quote Originally Posted by t_chance View Post
    REGAL BELOIT, SOME "WHO KNOWS WHAT" 5/16 304 BAR
    The last time I had this job I went thru 3 taps (broken teeth) on ten parts.
    I tried drilling oversize, big chamfers, down to 15 SFM. Nothing seemed to work.
    NOW 3/8 THICK NOT 5/16



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    Default Re: 1/4 NTP THRU 304 BAR

    OTHER TAPS WHERE OSG ELECTRALUBE AND REIFF & NESTOR



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    Default Re: 1/4 NTP THRU 304 BAR

    Why not thread mill it?


    Sent from my iPhone using Tapatalk



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    Default Re: 1/4 NTP THRU 304 BAR

    Pipe taps do not clear chips easily, so I would use 4 or 5 steps to do it. Decreasing amount of cut for each pass. Oversize holes for sure, as the standard for hand tapping has the tap cutting the sides walls way too much.

    Two Haas VF-2's, Haas HA5C, Haas HRT-9, Hardinge CHNC 1, Bother HS-300 Wire EDM, BobCAD V23, BobCAD V28


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    Default Re: 1/4 NTP THRU 304 BAR

    I have tapped a ton of npt threads in ss. I have had trouble with thread tear out of threads but I don't think I've ever broke one. I use taps like these.

    https://www.regalcuttingtools.com/pr...aper-pipe-taps

    I set the rapid low. Just as the tap reaches the r plane and starts spinning I add a heavy dose of tap heavy from a oil gun. I follow the stream up the tap to the height of tapping depth. In the other hand I keep the air hose. As the tap is retracted I blow a constant stream of air directed at the entrance point of the hole. This usually results in a clean tap you can follow right to the next hole and repeat. If there are chip that don't come off I feed hold and remove before it starts spinning again at the next hole.

    Ben

    Sent from my E6810 using Tapatalk



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    Default Re: 1/4 NTP THRU 304 BAR

    Thanks Ben.
    That was the problem, packing chips. My taps never snapped off, just chipped out the teeth. I'll give those a try.
    Tom



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    Default Re: 1/4 NTP THRU 304 BAR

    Threadmill. costs the same as two pipe taps, lasts a long long time, makes beautiful threads that gage perfectly.



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    Default Re: 1/4 NTP THRU 304 BAR

    Definitely thread mill.



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    Default Re: 1/4 NTP THRU 304 BAR

    4th vote for thread milling. Stop banging your head against the wall.



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    Default Re: 1/4 NTP THRU 304 BAR

    POINT TAKEN.
    I've banged my head against the wall for too many years. THANKS

    The boss wouldn't spring for anything more than a hand tap. He's a welder...



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