Seeking method to turn square stock round

I'd probably do it in a 4-jaw chuck with a process like I've sketched below. By turning the second part before you cut off the first you would be able to use a parting tool without an interrupted cut. The square end could be cleaned up on a sander or grinder. If you have a tail stock turret or capstan it would save tool changing time.

drawing.jpg
 
Perfect job for collet, if you had a turret box on your compound , 4 tools set up . Face and rough turn , finish turn , center drill , drill , chamfer, tap, then cut off . Turret LATHES are made for this type work. You will want the bar length through the head stock , not a bunch of short pieces. It makes holding in the collet easier. And the material being tubing when parting is easy. Looks like a gravy job , you'll do alright . Get the collet , my vote
 
Put in lathe and turn, drill, tap and part off, that easy. Don't worry about the interrupted cut, use a roughing tool then a finishing tool if the finish is a priority, you should be able to make hundreds of such parts with one tool if you are not in a hurry.

If you really want to enjoy yourself single point threads on the corners of square steel bars.
About 15 years ago I made a dozen or so parts in 1 1/2" square cold rolled steel bars about 30" long, 15" of which were threaded on the corners, such a racket this made. These were parts for the restoration of some manner of historic canal lock controls built in the late 1800's when it appears that time meant nothing. The deburring of threads with 4 interrupted cuts is a nightmare as you can imagine.

Good Luck
 
First never pass up an opportunity by new tools. But that would be easy in a 4 jaw chuck. If the square stock will fit through your spindle. Make first part part off losen jaws 1 and 2 advance stock and tighten. you should stay pretty close that way.
 
Thanks very much to everyone for your excellent and detailed responses. My plan is to buy the square collet and make sure that I have a round collet in the proper size for the 2nd procedure. I will post follow up results in the next couple of weeks.

Jim
 
You could borrow the technique used to make a cube in a cube. Bore a hole in a piece of round stock with a diameter equal to the diagonal length of your square stock. Then cut a lengthwise slit. Insert your square stock with one side straddling the slit. When you tighten the assembly in your three jaw chuck or collet, it will securely clamp the square stock.
Also available are square hole sleeves made by the Sturdy Broaching Co. that are made to be used for making boring bars and other tooling by drilling and reaming a round hole and silver soldering or loctiting the sleeve in place. For holding square stock, they can be slit along one corner and clamped in a 3 jaw chuck.
 
what I do is to use my Jacobs rubber collet chuck. find the size collet that fits over the square stock but find one that has metal inserts that is a multiple of 4 say 8 or 12 metal inserts then I line up the square points on the metal inserts and tighten the collet down and lock it in place works well to turn the end of square stock down to round. but not everybody has a Jacobs rubber collet chuck this method is very fast and accurate bill
 
I'd probably do it in a 4-jaw chuck with a process like I've sketched below. By turning the second part before you cut off the first you would be able to use a parting tool without an interrupted cut. The square end could be cleaned up on a sander or grinder. If you have a tail stock turret or capstan it would save tool changing time.

View attachment 231767
I recommend parting before "turn 2" otherwise ok
 
I was probably 14 yrs old, one of my first tests in school was giving one piece of square stock and one
piece of round stock.. We were instructed to make the square round and the round made square. No
books no nothing and no talking. Pick your lathe, I want these parts at the end of the school day. Any
way only two of us managed this, I was brought up in grease and oil and gears so at least I had a little
brain. Till this day I always thought the teacher had us do off the wall projects because he was
weeding our thinking levels . Some kids couldn't even operate a crescent wrench. This was 55 yrs ago
and I now realize I rather be the student than a teacher kids must have drove him to a bottle of Jack
when he got home. Picture a 60 yrs old gold rim glasses about 5' 5'' always wore one of those knitted
hats with a ball on top (you see Christmas time).............. Just rambling again you can do it.......sam
 
Thank you for sharing that story. What a great way to learn! Quite frankly at my age with no instructor, I approached almost every project the same way. If something looks like it's possible I go ahead and try to do it. The major difference of course is without the internet I would never be able to accomplish these things!
 
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