Picking up internal thread to cut deeper ?

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Scruffy

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I'm dealing with a 2 inch by 12 thread hyd cylinder rod. I had to get a new nut for it and the threads seem to be to shallow, as in .050 thousand.
How do I pickup the existing thread to cut it deeper?
I have cut a lot of threads before. I will be using my 16 by 54 American pacemaker.
Thanks scruffy Ron in Ohio
 
You do it just like picking up an external thread.

Set the tool properly as normal for cutting internal threads
Move the carriage into a convenient position
Engage the half nut on a line
Adjust the compound screw to get thread engagement
Disengage the half nut and wiggle into position using both the compound and cross slide screw, this is done by feel.
Re-engage the half nut and see how it feels, does it stay on the line?
Adjust as needed.

Nice lathe :)
 
As Jim said above but I would use a trick at this step
JimDawson said:
Adjust the compound screw to get thread engagement
Click to expand...
With the half nuts closed and you are adjusting the cross slide and compound to get close to thread engagement, leave the threading tool loose enough in the holder to be able to slide it by hand into final engagement. Hold the tool in the threads while you tighten the tool holder.
 
I had to do something similar when I was a Freshman in college. Prior to doing that I had only single pointed two external threads. I had to pick up a 3/4-40 internal thread. A bright light and a magnifier helped a lot. It is important you hold pressure on the half nuts to eliminate backlash when lining up the threads.

Mu original job was to face off the end of a microscope tube to establish the right length. I chucked it in a Jacobs Rubberflex collet chuck. I applied a bit too much pressure with the chuck and shrunk the end of the tube. That is why I had to re-cut the internal thread.
 
I use a Digital Inspection Camera because I can not bend my old neck and my eyes leave a lot to be desired!
298661

Hold the camera in the tail-stock and I use a magnetic indicator base setup for the small eyepiece.
I also need a lot of light directed at the work piece!
 
That is a nice lathe for sure . Any pics of it ?
 
Something was wrong. I read Jim Dawson's answer and 30 minutes later I was finished.
Went so well it was scary. Nut went on with a nice tight fit.
Thanks for all the help. I have posted pics of some of my machines but I don't know how to find them.
Thanks scruffy Ron in Ohio
 
Congrats! I have done as many have said for internal and external threads. My only trick is that I first get the tool centered on the crest of the tread since it is easier to see, then I offset 1/2 of the thread pitch and move in the calculated depth. This seems safer to me and prevents the risk of re-cutting the existing thread too deep.
 
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