Threadmilling NPT threads

[jspangler]

Hi

Is there a formula handy, or someway to figure out the taper size to rough mil a pocket for a 3" - 8 NPT internal thread? I need to threadmill the pocket on a Fadal (Older than dirt...) using a single boring bar type cutter. Apparently that's what the last guy here did, but I can't find any existing NC files for the part.

 

Help...

 

Thanks

John

 

Using...

Mastercam 9

Fadal CNC 88 control

[gcode]

John,

I believe the taper is 1 degree per foot(radial)

or (1/12 = .0696).... thats from memory.

I've got the calculations at work.. I'll check them in the morning.

[?Mark]

Angle is 1 deg 47 sec (1.7833333 deg)

The dia at the top and depth you can pull from Machinery's Handbook.

I don't have it at home, but try this here to get you going.

[DavidB]

NPT taper angle

 

HTH

[jspangler]

Awesome, that's exactly what I need.

Thanks

John