Seeking method to turn square stock round

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I would like to make some small threaded inserts similar to the attached picture. I can buy them but not in the size that I need. The square section is three eighths of an inch in the total length is a little over 1 inch. I'm really not looking forward to setting up the 4 jaw Chuck on multiple pieces. It occurred to me that a square collet might be the best approach. I'm also very concerned about the interrupted cutting necessary until the square stock becomes round. These parts will be either mild steel or brass. They will also be threaded through the entire length. Would appreciate any advice

Thank you in advance.

Jim

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so long as you don't try to get too aggressive in your DOC, you should have little problem holding it a collet
12L14 steel cuts like butter, brass would be easy to machine.
6061 aluminum may also be a consideration- easy to machine and inexpensive too
 
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.
 
A slightly more wasteful option would to turn this out of round stock,
thread, etc, then part off and put your part in a 5c collet block and square off
the head in a mill. Asuming you have a mill...

The other thought I had was, once you center up the first part in a 4 jaw, if you
loosen 2 jaws at right angles say one full turn of the chuck key, how far off will
you be if you tighten up those same two jaws one full turn?
 
what if you setup your square stock in 4 jaw long enough to make several parts? Cut the rounds leaving square pieces in between rounds. Then you cut the pieces on bandsaw or hacksaw. Then for rest of the operations you just use 3 jaw.
That way you only use the 4 jaw once for several parts.
But hey i am a self taught noob so my theory probably sucks.
 
What is the issue with using the 4 jaw chuck? You said the issue was that there were multiple pieces - are you making lots of them? If it is <50 items, that wouldn't be a big deal - loading in/out of the 4 jaw.

The other thought I had was, once you center up the first part in a 4 jaw, if you
loosen 2 jaws at right angles say one full turn of the chuck key, how far off will
you be if you tighten up those same two jaws one full turn?

Fradish is right, just working two jaws puts you pretty close (I find I am within 0.005" on the first try - it won't come back the same when the next piece goes in, but it will be close). Use a wide tip on the plunger of the dial indicator and it will likely ride right over the corners.

An interrupted cut on a little piece like that is not going to be an issue to the machine. The tooling may not be too happy (start with HSS and don't get too aggressive on the depth of cut).
 
I do this kind of thing routinely, so to make these in quantity I'd start with square stock and use the square collet, and turn the round section in one pass with a sharp insert working up close to the collet. Then I'd shove the stock farther out, part off the piece a bit overlength, repeating until I had as many as I need.

It would be a quick process, and there would be sufficient support to turn the round section without difficulty. I'd then switch to a round collet, grip the part right at the shoulder, and quickly face them off to the same length without moving the lathe carriage. Then back in the collet for drilling and threading I'd drill all of them first, then thread them.
 
I'd then switch to a round collet, grip the part right at the shoulder,

Hopefully the round part is a collet size. If not might have to use an emergency collet or ER series.
 
Hopefully the round part is a collet size. If not might have to use an emergency collet or ER series.

Ah, that is a point - I assume too much sometimes. Natcherly, you'd check that before proceeding.

It wouldn't be a problem for me because almost all of my work is in collets, so I have FULL assortment of 5C - 64ths, metrics, #drill 1-60 , square, hex, and even some rectangular, along with all the ones I've bored for specials like tapered or eccentric stuff. I also find it handy to have duplicates of common sizes, for use when I need to move repetitively to the mill to use the spin index or collet block.
 
This is not going to work for the op, however at times like this a 4 jaw scroll chuck is well worth looking into and a good investment to have on hand.
I have one and leave it on the lathe all the time in place of the 3 jaw, the only time I go to the 3 jaw now is for hex stock.
 
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