Thread cutting with die 1

[alansimpson]

Would anyone know of a guide to hand cutting threads with die. Small metric threads M2-M12.

Specifically needing information on blank diameters, how to start thread and how to keep die straight.

Thanks.

 

[saberblue]

Machinest Hand Book

 

[btrueblood]

Alan,

I almost always try to use the die on a lathe, chucking the die and holding the workpiece (stock) on/in the tailstock of the lathe. This ensures that the starting cut is made with the workpiece held on-center and (more critical) perpendicular to the die face. An even 45 degree chamfer on the end of the workpiece helps for starting. The chamfer should run out below the minimum thread diameter. Note that I'm just using the lathe for starting the thread, rotating the chuck by hand. As soon as I get a full turn or two, I open the chuck, and continue cutting the thread by hand, clamping the stock in a vice.

As I said, almost always. The exceptions are typically when I'm not near a lathe, and the results are (usually) a thread that wanders off-center after about 10 or 15 turns.

You could probably make up a jig that holds the workpiece (stock) in a v-block, and provides a flat surface (perpendicular to the v-block axis) to rest the die face against as you start the thread, and accomplish everything that using a lathe would do.

 

[saberblue]

You can do the above in a drill press as well

A.R. "Andy" Nelson
Engineering Consultant
anelson@arnengineering.com

 

[JohnFox]

Hi Alan,
ditto. Use a manual lathe to hold the die and workpiece. Turn the die by hand and very carefully feed the work into it. When you are finished very carefully push against the workpiece and turn the die to remove the workpiece....

best regards,
JohnFox

 

[11echo]

Using a lathe would be my first choice! ...However there is another technique I've used with a drill press. You drill the hole in your work piece with the drill press. Then remove the drill bit and chuck up the tap. DO NOT START THE DRILL PRESS UP!! But with your hand bring down the chuck and the other hand grab the chuck and turn it by hand ...starting the threads. You'll only get afew threads started but it's normally enough to continue and to keep it straight with a normal tap handle. ...You'll also need your shoulder to help bring down the chuck as you are starting the threading ...alittle weird, but it works pretty well on small diameter threadings. Good Luck!

 

[eeinpa]

I agree with the drill press and lathe ideas. I'm no master machinist, but both methods have allowed me to have good success threaded some picky holes. Before I knew these tricks... look out

I would like to add that you can get special tap handles and die holders which make using a drill press or lathe much easier. Check out 8326A11 and 2550A65 at McMaster.com. Neither of these are complicated, you could make something yourself if you have a lathe. But they are one of those investments that pays for itself on the first saved job!

If you purchase or make a die holder like this, I'd suggest machining flats on it so you can turn it with a wrench if you need to. I find it easiest to lock the headstock holding the part, and then turn the die holder while it's loosely held in a chuck in the tailstock.

Good luck!