Ed; you should be fine. Setting the radius would be a bit of a chore, but it should work just fine.

On a CNC mill, one can "turn" a piece in the spindle much like you are trying to do here, except of course with CNC you can program the tool movement, if the tool is firmly bolted to the table. (i.e., no rotary needed)

Tell us how you get on.

John.

Agree with John that it will work just fine but setting up will be more than a chore if you need a decently accurate ball curve rather than a simple blending radius. Even with a simple radius setting needs to be pretty good if the results aren't to appear a bit wonky. The Mk1 human eyeball is good at spotting such errors. If going for a full good ball it can be very hard to keep straight where remaining errors are and what adjustment corrects them once you've got to the "fairly good but not good enough" stage.

I'd look into mounting up the lathe topslide on the rotary table to provide cut adjustment.

If you have a boring head with sufficient travel the "cut with the work and spindle axes at 45° to each other" works well and probably has a lower frustration index.

That said if you have a boring head it can be used as a basis for an effective up'n over type ball turning tool without a vast amount of work. Assuming you have a reasonable starter lump in the useful bits box I'd estimate that a very useable up'n over tool could be made in less than twice the average time taken to set-up what you propose and produce a nice workpiece. One made you have the up'n over tool ready to go at any time but the rotary table on the mill has to be set from scratch for each use.

Clive

Edited By Clive Foster on 17/02/2015 23:17:43

Edited By Clive Foster on 17/02/2015 23:18:20

Have you thought about generating a sphere using this method.

http://www.ctemag.com/aa_pages/2013/130310-ShopOps.html

http://www.ctemag.com/aa_pages/2013/130310-ShopOps.html

Phil

clickable link added.

Edited By John Stevenson on 18/02/2015 00:40:01

Hi Ed,

I have done a lot of radius turning on my mill, and as Fizzy has said you have to be aware of backlash in the rotary table. I learnt the hard way and smashed some of the teeth in my rotary table. Use sharp tooling, take small cuts and use conventional milling, not climb milling.

Paul.

I've had no problems in aluminium alloy or cast iron. I turned the patterns in the photo below on my home-made rotary table, and the other photo shows profiling a steam engine cylinder.

I also turned v-pulleys for my lathe (when the motor went pop) using the mill so both the rotary and cutting elements of what you propose are quite practical.

Neil

Edited By Neil Wyatt on 18/02/2015 09:43:30

Hi
Turning on a mill drill
Nobby

To quickly centre the rotary table, I have a large steel ball(it won't go up the 3MT spindle nose of the mill), I place the ball on the 2MT hole in the RT, then bring the spindle down, rotate the spindle by hand, then clamp the RT to the mill, It might not be the propper way, but it's my way, and it seems to work.

Ian S C