Internal Single point threading

[benmychree]

Hi Benmychree, Just out of curiosity how will it gall the threads on the spindle? I am a newbie and don't understand how/why it would. I am going to attempt a similar project and bought some steel to do it, not cast. Now I am rethinking my purchase...

All commercially available lathe chuck mounts are cast iron, and there is a reason for that, which is that for one thing, crud and small chips are sure to get into the interface of the spindle threads and the backplate threads, no matter how clean we think they are, and we know how hard it can be to remove a chuck after taking even not-so-heavy cuts; if there is a piece of grit or small chip in that interface, it can start a gall that keeps getting bigger as we try to unscrew the chuck, damaging the spindle and backplate threads, and I have seen lathe spindles that have been damaged in this fashion. Cast iron, being softer than steel can imbed these small particles, avoiding damage.
Thread protectors and possibly collet adaptors that thread on the spindle are OK to be made of steel because, for one thing they do not get jammed on by cutting force and impact that we see with chucks. My advise is to save the chunk of steel for another project and buy or have made a cast iron blank.

 

[Armourer]

All commercially available lathe chuck mounts are cast iron, and there is a reason for that, which is that for one thing, crud and small chips are sure to get into the interface of the spindle threads and the backplate threads, no matter how clean we think they are, and we know how hard it can be to remove a chuck after taking even not-so-heavy cuts; if there is a piece of grit or small chip in that interface, it can start a gall that keeps getting bigger as we try to unscrew the chuck, damaging the spindle and backplate threads, and I have seen lathe spindles that have been damaged in this fashion. Cast iron, being softer than steel can imbed these small particles, avoiding damage.
Thread protectors and possibly collet adaptors that thread on the spindle are OK to be made of steel because, for one thing they do not get jammed on by cutting force and impact that we see with chucks. My advise is to save the chunk of steel for another project and buy or have made a cast iron blank.

Thank you for the reply! Makes total sense now, guess I will go back shopping again!

 

[Billh50]

I have never seen steel to steel gall. I have seen steel to aluminum and stainless to steel gall. But never steel to steel. And I thought chuck adapter and face plates were made from Cast Iron because it absorbs vibration and avoids vibration suction. Also is cheaper and faster to cast.