Torque Needed For A 1/4 Pipe Tap

[Waterlooboy2hp]

Leave it to me, to come up with the odd questions. I am producing some parts, out of 6061 Aluminum 3/4" hex bar stock. One end gets drilled and tapped with a 1/4 pipe tap.

Tapping them by hand, gets old pretty quick. Got to thinking, that maybe I could use battery powered impact wrench to do the job. A 3/8" drive produces about 100 ft. pounds of torque. Any idea if that would be enough to drive the tap?? --- The 1/2" drive will give about 240 Ft. Pounds. I would prefer the smaller one, due to smaller size and weight. I know a tapping head would be the best choice, but one large enough is just to expensive.---- John

This is the part, that I produce ---.

 

[Heavy Metal Doctor]

My 2 cents - do it by hand or use a tapping tool for a mill / lathe. You can clean up existing threads with a small impact driver, but I'd be concerned the shocking / hammering would snap it off trying to cut new threads. A smooth running drill driver might work, but then you'd still loose sense of feel that makes for successful tapping without damage / breakage.

 

[fsae0607]

^^ to add to what he said, if you have a drill press, you could rig up a tapping attachment if you're cranking out many of these.

 

[zkling]

Depends what you are drilling with combined with the depth you are tapping to. I use a 3/8 butterfly impact and jacobs tap chuck quite often to drive taps, bet it would put that through with ease. The tap isn't soo small to be snapped off, but you are also fighting the taper cut. Plenty of lube and a sharp tap. I wouldn't start with a 1/2" impact. Depending on how you are making them I'd just use a floating tap holder in the lathe tail stock.

 

[jeepinerdeep]

I've tapped some stuff with a cordless drill. 1/4 pipe is a pretty stout tap. I chuck them on the round part of the tap not real tight so it could slip. I wouldn't impact.

 

[Waterlooboy2hp]

Depends what you are drilling with combined with the depth you are tapping to. I use a 3/8 butterfly impact and jacobs tap chuck quite often to drive taps, bet it would put that through with ease. The tap isn't soo small to be snapped off, but you are also fighting the taper cut. Plenty of lube and a sharp tap. I wouldn't start with a 1/2" impact. Depending on how you are making them I'd just use a floating tap holder in the lathe tail stock.

===============================

Sounds like it may be worth a try, although there seems to be more cons than pros about doing it. I do like a challenge. I cut the blanks on a 6" chop saw, with a carbide tipped blade. ---- Then on my 7x10 mini lathe, I turn one end, for the 10mm male thread (also a few for a 12mm thread).--- I start both the pipe tap (with a live center) and the 10/12mm threads (with a die holder I made for the tailstock), in the same lathe.

I use a 5c collet fixture, on my WT 900 drill press in the basement, to center drill and then drill the hole for the pipe tap. Then, I hold the part in a vise and finish the pipe tap and mm thread by hand. Back into the fixture, for the final 1/4" through hole.

At this point, I expect to be making these parts on a regular basis. The pipe tap is the slow part. The rest is pretty quick.

My 11" Logan lathe is in a small shop, off the back of my garage. My wife suffers from Paranoia. It is not good for me to be out of her line of sight, for to long, when I am out of the house. I set up a Mini Machine Shop in one end of her kitchen, so I could be right there, if she needs me. ---

I have a click type torque wrench. Think I will try using it to tap a hole and see if 100 foot pounds is enough. I am making these additional assemblies at the same time, so I am as busy as a bumble bee, stuck in a tar bucket. Thanks for responding to my question. --- John

 

[WhiffySpark]

I'm no help but I use a 3/8 14.4 v impact to retread everything. Never tried a tap

 

[A_Pmech]

The tap is driving hard because the hole is smaller than the minor diameter of the tap. This causes the metal to "bunch up" behind the flute as two chip streams converge.

There are several ways to solve the driving torque problem.

1) Ream the hole with a tapered pipe reamer before threading.

2) Step-drill the hole.

3) Resort to a skip-tooth tap.