I had 1" galvanized pipe cut to size and threaded at a large hardware store but they still won't screw all the way into the fittings. When I compare them to the pre-threaded pipes I bought, the pre-threaded appear to taper slightly all the way down the threads and screw in just fine about a 1/2" but the store threaded pipes only screw in about 1/4" or less. I've tried WD-40, Vaseline and I even filed the ends down a little to remove any burrs. They don't need to be leak proof because I'm using them to building a closet organizer but they do need to fit together. Any suggestions?

  • 1
    NPT threads should taper. If yours don't, ask them to do it again.
    – isherwood
    Commented Jan 6, 2016 at 19:26

1 Answer 1


I use to run a pipe threader at Home Depot, and my cuts always fit just like the pre-threaded pipe. Their machine could have been out of adjustment. If the threads don't look the same as a pre-threaded pipe, and they don't fit the same, something is wrong.

For what you're doing, 1/4" of pipe thread might not provide the strength you need even though it doesn't have to be water tight. Take it back and show them the problem.

  • I also ran a pipe threader at Home Depot and this is exactly right, sounds like they had a badly maintained machine, a bad alignment, or somebody just did a bad job threading it. Commented Jan 6, 2016 at 23:54
  • There is a lever the end of the pipe pushes to release the jaws once the threads are "done" and if the machine is very dirty, or the cutting head is loose and worn it pops off too soon. What you end up with is threads that are too short and therefore not tapered enough, but unless you know what you're looking at, it looks like it worked.
    – JPhi1618
    Commented Jan 6, 2016 at 23:58

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