What Size For Threading?

[benmychree]

I made that statement in the support of an amateur as benny said. I've long since graduated from using dies to finish threads with. Occasionally, I will grab a die to chase a thread if needed or even the check a fit when I don't want to use a thread mic, too. Kind of hard to break old habits!

In the future, call me John, my given name; I use the name benmychree as my e bay identity, it is after the ship of that name that plies between the Isle of Man and Liverpool; my dad's mother's family was from there; there is a part of me that identifies with the Isle.
John York

 

[savarin]

When I need to grip threads I slit some nuts and screw them on, tightening the chuck ensuring the slits are between the jaws and not under them squeezes the nuts to grip the threads.
I know its not exactly centred but I've always found it close enough.

 

[benmychree]

Near enough is close enough! In my apprenticeship, our company, Kaiser Steel, had drawings that were tolerenced in a fashion that was "good enough for the times" (my words), nothing like today's drawings and tolerences; given that, if there was a "problem", that is something that did not meet the specs, there was nearly always a way to make up for it on the mating part; the drawing was something to aim at as the personification of perfection, but, finish and fit were what was important.

 

[Tozguy]

For thread charts, littlemachineshop has some handy ones, for example http://littlemachineshop.com/instructions/UN_Thread_Data_Chart Rev D.pdf

To hold the 7/16ths end in the chuck, I would jam nuts on it as already suggested but I would use as many nuts as will fit. Use enough torque on them to line up the flats of all the nuts. When turning it will be obvious if the stud is held enough.

Once the stud bolt is turned to the .311'' to .301'' range, add a chamfer on the end to help in starting the die straight. Hold the die in the holder that came with your set but use the tailstock to push it onto the stud. The square end of the TS quill should keep the die square to the stud. Don't forget the lube.

I would start it by turning the die handle by hand while using the other hand to turn the TS hand wheel to keep pressure on the die handle. Then when it gets harder to turn use both hands on the die handle and forget the TS. Lathe must be in its lowest gear but not running.

 

[RandyM]

In the future, call me John, my given name; I use the name benmychree as my e bay identity, it is after the ship of that name that plies between the Isle of Man and Liverpool; my dad's mother's family was from there; there is a part of me that identifies with the Isle.
John York

John, I suggest that if you prefer to be addressed by your given name on the forum that you add it to your signature for everyone to see.

 

[benmychree]

For thread charts, littlemachineshop has some handy ones, for example http://littlemachineshop.com/instructions/UN_Thread_Data_Chart Rev D.pdf

To hold the 7/16ths end in the chuck, I would jam nuts on it as already suggested but I would use as many nuts as will fit. Use enough torque on them to line up the flats of all the nuts. When turning it will be obvious if the stud is held enough.

Once the stud bolt is turned to the .311'' to .301'' range, add a chamfer on the end to help in starting the die straight. Hold the die in the holder that came with your set but use the tailstock to push it onto the stud. The square end of the TS quill should keep the die square to the stud. Don't forget the lube.

I would start it by turning the die handle by hand while using the other hand to turn the TS hand wheel to keep pressure on the die handle. Then when it gets harder to turn use both hands on the die handle and forget the TS. Lathe must be in its lowest gear but not running.

One should always chamfer the end of a thread, whether one is cutting it with a die or single pointing it. The above procedure is by no means a guarantee of not ending up with a wobble in the thread, hence the suggestion to start the thread by single point and finishing with the die.

 

[Tozguy]

I need to make a special stud. It needs 7/16" nc threads on one end and 5/16" nf on the other. I thought I'd use a 7/16 bolt and turn it down and use a die to thread the other. I have experience tapping holes and have a chart for what size drill to use. I have no idea what size to turn the bolt to to thread the other end. Is there a chart someplace I can copy to I don't have to keep asking dumb questions?

John, based on the initial post my comments were aligned on using a die. There was no question about single pointing. If I got that wrong and single pointing is on the table then post 18 makes the most sense to me.

Plus, my comment about chamfering the end was to ''help starting the die straight'' and not to guarantee anything. However, the chances of starting a die straight by pushing with the TS are pretty darn good in my experience.

 

[benmychree]

John, based on the initial post my comments were aligned on using a die. There was no question about single pointing. If I got that wrong and single pointing is on the table then post 18 makes the most sense to me.

Plus, my comment about chamfering the end was to ''help starting the die straight'' and not to guarantee anything. However, the chances of starting a die straight by pushing with the TS are pretty darn good in my experience.

My experience in starting dies by pushing with the tailstock have not been good; perhaps it has to do with the die stock that I use. I recently got a Monarch 9" lathe probably from the 1920s or 30s, for it, I bought a set of button die guides; the shank fits in the tailstock taper, and there are sliding die holders that have a slot cut in their length behind the die that fits over the straight portion of the shank, which gas a tapped hole for the "key" that fits in the slot of the shank, so the tailstock remains stationary and the die with sleeve is slid into position to cut the thread; ,have not used it yet, made in China, kinda sloppy fits, but I guess it will work OK.