generating taper threads

[srinivas.routhu]

Hi all,


Need help ingenerating taper threads which i need to model from an old hand made drawings, in the image attached 2011-09-24_052345_taper_threaDS.zip


in the section view the dimensions 1/2 NPTF thread is shown with '0.864 AT STD TAPER', The taper thread is designated Dia.0.67 to as 0.817,


but left bottom corner the view The taper thread is designated as NPTF thread blank from Dia.0.67 to as 0.805.


Can some one suggest the correlationof both the views to generate a thread model.

Thanks in Advance,


Srinivas.Routhu

 

[mekaneck]

0.67 is the diameter of the 45 degree chamfer, it is not related to the thread.


The MFT 0.60 length means "minimum full thread" indicating the threads must be fullly cut to that depth and then can begin to fade. All you should have to specify on your drawing is 1/2" NPTF and the 0.60 MFT, the supplier will know how to generate the thread with standard tools. If you need to know the exact thread details, they are specified in ANSI/ASME B1.20.3.


The standard diametral taper for NPT and NPTF threads is 1/16, or ~1.79 degrees measured from the thread pitch diameter to the center axis.


I'm guessing this was intended for a rolled (instead of cut) thread forming process, and that is the reason for the detailed "thread blank" view.