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RandyJones20-Turquoise
20-Turquoise
October 8, 2009
Question

WF4 npt thread note calling out incorrect drill dia?

  • October 8, 2009
  • 1 reply
  • 588 views

With WF4 we gained the addition of tapered threaded holes such as NPT. I am questioning the clarity of the thread note that Pro/Engineer is creating for these holes. Take a 1/8-17NPT hole for example for which I have attached a screen shot of the hole note. Notice the hole note is calling out this: "Q" DRILL (0.344)


The "Q" drill is correct ,according to Machinery's Handbook 27th edition, however a "Q" drill is NOT 0.344 it is 0.332. I have opened a call with PTC on this and what I am getting back is this: "For tapped hole, the NUMBER_SIZE is mapped to TAP_DR and DIAMETER is mapped to MINOR_DIAM_START of the hole file."

To me the taper thread hole notes are very confusing and could easily lead to using the incorrect drill size. So my question to all you tapered threaded hole creators out there is this. Should the hole note read like this (the PTC way):

"Q" DRILL (0.344)

or should it read like this (with the "Q" and the 0.332 in sync)

"Q" DRILL (0.332)

 

Thanks

    1 reply

    C
    CBenner1-Visitor
    1-Visitor
    October 8, 2009
    Personally we don't call out the drill size, preferring to trust that to the fabricator of the part, however, that said I think the thread note diameter should coincide with the "Q" drill size as much as possible. This is not the first time I've seen this. With the EFX module, we opened a call last year questioning the dimensions of some of the steel frame members, which did not match the dimensions from the steel manufacturers (which I believe are ANSI or ASME standards). They did react quickly so I guess they took that one pretty seriously.

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