Technical, Techniques, Hints, and Tips > Engineering Techniques and Materials.

How to: thread a hole or rod/shaft

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Brian60:
As a follow on to the other how to on doing a centred hole in material. The same technique can be done for threading.

It doesn't matter whether you are tapping a hole or threading a rod with a die. If it tapping a hole, mount the thread tap in the drill press and the work material in you machine vice (I assume you already have the hole drilled) Lower the drill press to the hole and then turn the chuck by hand to tap the hole, do not turn the power on! As long as you keep light pressure on the handle of the drill press it will wind into the hole easily.

If you are tapping a rod/shaft ( this is shown in the photo)  mount the threading die in the machine vice, I use a piece of ply to keep it laid flat and level. Mount your shaft in the drill press chuck and once again, without using power, lower it down to the die and turn the chuck by hand.

WHY DO THIS? you ask.

Well simply there is nothing worse than holding a tap or die in its toolholder and then having to turn it onto the work and hope everything is parallel when you finish. Doing it this way, the thread is perfect every time. My photo shows the tapping die in the machine vice and a brass rod to which I have added thread to the end of in the drill press chuck.

CGAux26:
Yep, that's how I do it.   :-))

Mark T:
Another great tip worth sharing there Brian and I have used this method many times and it gives a nice straight and square thread cut.  Using taps this way is a pleasure and is far better than using a hand held tap holder for a perfectly straight thread.


Personally I don't like die nuts and I've only really used these to clean existing threads that have maybe misused or have become damaged.  I prefer split dies so that I can adjust the cut and get a nice tight fit for the thread.  But I am a bit old fashioned that way and I bet that not many people use split dies now.  You don't get the taper effect on the thread using split dies.

grendel:
I used a similar method to re-tap a bigger thread into a lathe faceplate, I bolted the faceplate to the drill press bed, then turned the 3/4" tap by hand, this left the faceplate  true and straight.

RAAArtyGunner:
Very good.

The difficulty in getting the thread 'square' has been a deterrent.

Not the same as threading plumbing pipes where being 100% dead square is not as critical as a spinning propeller.

Keep them coming.

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