Torque when tapping 1/4" NPT in brass

I am making a brass manifold for different kinds of compressed air
(and I will also add a vacuum manifold there as well), out of a 10"
brass hex bar.
As I am tapping it for 1/4" NPT, with a McMaster tap, I am concerned
to not break the tap. Anyone has any idea what torque is permitted?
thanks
i
Reply to
Ignoramus15962
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Is your hole tapered ? If so I doubt you will over torque it . You can buy standard hand reamers for NPT . Luck Ken Cutt
Reply to
Ken Cutt
No, it is not tapered, just drilled to 7/16".
i
Reply to
Ignoramus15962
I doubt this will be a problem. A good tap that size would be difficult to break by hand.
Reply to
Richard J Kinch
Tapping brass with a straight hole to an NPT taper takes a LOT more torque - even with a little 1/4NPT tap - than you'd think. And without the proper cutting fluid, brass really GRABS a steel tap. Any time you're full-cutting with a dry tap, you're "SQUEEK"-ing badly. I'm more comfortable with taking, say, half-to-one turn cuts followed by a quarter-turn backout to clear the chips. You don't want to back out very far with a tapered tap, lest you jump a thread.
LLoyd
Reply to
Lloyd E. Sponenburgh
Try step drilling it to approximate the taper.
Reply to
Nick Hull
I've tapped a bit of steel 1/4" NPT using the tap drill off of the chart w/o breakage. I've always thought brass to be a bit easier imho.
If something feels wrong, it likely is. Go with your feelings and use a lubricant.
Wes S
Reply to
clutch
Thank you Wes, it worked fine.
i
Reply to
Ignoramus19864
Go with your feelings and use
That's what she said.
Reply to
Jim Stewart

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