Npt thread

[celhz]

Hey guys long time lurker here,

Our shop was commissioned to do a 0.500 - 14 NPT Thread in a SS forged material.

This is the first time I do NPT threads. The customer sent us a gage with 3 planar surfaces along the thread. I am using this explanation to measure it.

https://www.threadcheck.com/technical-documents/taper-pip-thread-gages-pg12.pdf

I wanted to know if you have any recommended cutting conditions.

Seco recommends the following with an HSS tapper (MTH-1/2-14NPT-XC-V048):

Cutting speed 29.5 sf/min
Coolant media Emulsion 10%
RPM 137 rev/min
Feed speed 10 inch/min
Recommended pre-hole diam 0.7047 inch
Maximum pre-hole diam 0.7067 inch

But I am Using a 1/2-14 NPT 4 Flute High-Speed Steel Standard Flute Tap from Kennametal. And the previous supplier used S20 F1.4 in/min. Which is different from SECO web page.

Thanks in advance for the help,

 

[yardbird]

Sounds like you know what to do. Drill, taper team, then tap. Spin and feed the tap at the rate of downwards twist the thread is, then have at it. Might do a couple practice shots in something soft to get your thread depth dialed in before you do the forging?

Brent

 

[GENERALDISARRAY]

thread mill

 

[mmurray70]

thread mill for sure

 

[celhz]

Thank you all for your responses. I will try to implement a threadmill.