how to hold

[capt.ron]

how do i chuck up a piece of 6 inch round steel x 1/2 thick to turn the diameter down

 

[donthack]

Is it possible to bore a hole to mount on a mandrel? Then you could easily turn the O.D. Or you could get trick and mount it to a rotary table, do a little clamp and un-clamp, then use a end mill. Good luck!

 

[chuckorlando]

I would start with a 7in long piece and a center my self. Then part it

 

[JimDawson]

It would be helpful if we knew what you have to work with. Lathe? Mill? Rotary Table? Size of the equipment? Type/size of chucks? Can you put a hole(s) in the part?

I know how I would do it in my shop, but I also know what I have to work with here.

 

[GK1918]

It looks like (I'm thinking) you don't want a hole for a mandrel? Perhaps a limited amount of tooling? I have run into this situation,
and what I did was chuck up something smaller in diameter than your 6'' piece. Face it. Keep this "stub" short in the chuck. Clean
both good and clean apply epoxy on both. A piece of wood to the six inch and stab it with the tail stock center. Touch off with
tool bit turn by hand and get it pretty well centered. Apply more pressure on the tail stock, and walk away till it cures. Turn
taking light cuts. To remove simply warm up the part.. It does work but take your time....

sam

 

[davidh]

weld a round stub to the center of the round, that will fit in your chuck, grind off the stub when done turning

 

[donthack]

Well Captain how about a update? :think1:

 

[Round in circles]

how do i chuck up a piece of 6 inch round steel x 1/2 thick to turn the diameter down

Do you have a four or three jaw chuck ? Will your lathe " throw " take the six inch piece ?
Can you remove your chuck jaws & turn them around like I can on my three and four jaw chuck ?

If so you may be able to do a simple jaw reverse and turn 1/3 of the shaft against a centre point , then refit the turned down bit in the wide jaws or in the chuck with the jaws set back to the normal positions .

- - - Updated - - -

how do i chuck up a piece of 6 inch round steel x 1/2 thick to turn the diameter down

Do you have a four or three jaw chuck ? Will your lathe " throw " take the six inch piece ?
Can you remove your chuck jaws & turn them around like I can on my three and four jaw chucks ?

If so you may be able to do a simple jaw reverse and turn 1/ 2 of the work at a time using a rotating centre point or even a greased large turned flat bolt head in a tail stock rotating or fixed chuck to keep the work held steady in the lathe chuck jaws .
Then if possible refit the turned down bit in the wide jaws or in the chuck with the jaws set back to the normal positions . Perhaps also make a simple thin backing/plate plate or two using the lathe to keep the work pushed forward in the chuck jaws to stop it sliding back inside the jaws .

 

[capt.ron]

i have a 12x36 craftsman and i have 6in 3 an 4 jaw chuck i have been drilling a hole welding piece round stock and turning it that way but as you know its hard to get it true because of the weld pull most of the time that don't matter but this time i am making a jack shaft that has to fit in a insert seems like i have to do this alot and i didn't know if i was missing something i did not get any tooling with the lathe just been buying tooling as i need it thanks for the help everybody

 

[xalky]

I like to use soft jaws for things like this. I do a lot a lot of discs in my shop. I'll machine the soft jaws to the diameter I need x 150 to 200 thousandth deep. Chuck up the piece and turn the OD down right to the jaws, then flip the part and do the remainder. Most of the time it's within a few thousandth s between one half and the other. Close enough, most of the time. You can do a similar thing with a jaw chuck and get it spot on. If you only have hard jaws, you have to space it off the back to get an even spacing. I've used parallels to get the spacing right. Just make sure you remove the parallels after you've clamped the part and spin it up.