Having very limited space in my garage I am wanting to get the most capability out of my little Partner I mill as possible. I have been looking at adding some turning capability to it and I'm interested in anyone's general thoughts, comments, or experiences about the best way to proceed. I honestly don't have any high production or specific needs in mind for using my mill as a cnc lathe. I guess working on my mill is just as much a fun project to me as the parts I'm making on it, So i'm not exactly worried about whats the most practical, or just using something to, "get by". I know any of my options below will take a lot of time and effort, but it not only needs to give me the most capability possible out of the CNC axes I have available already, It has to be something fun and Cool!!


The way I see it I have 3 options, 1 of which I'm not sure would actually have turning capability...


Option 1. - Building a tool gang to be fixtured in a vice or mounted to the table somewhere and clamping work stock in the spindle.
This is the most obvious and cheapest solution I can think of to be able to turn some parts with my mill, but, it also leaves a lot to be desired.
There is a company who makes a tool gang and chuck adapter to do this already and is basically how I would make mine. Mill2Lathe!

Pros:
Cheap
Easy to make
Proven theory with little foreseeable hick-ups before productive work could be accomplished

Cons:
Short max length of stock allowed.
Would not be able to use bar stock and pull out to length for jobs.
Not really that fun of a build.
No live-axis milling options.



Option 2. - Add a dedicated turning spindle to the machine, mount tool gang to the side of the spindle.
There is a company that sells something like this as well, they also offer R8 style turning tools for it, which I think is pretty neat.. I still think a tool gang would be the best route to go however. Sturges Turning Head

This option sounds like the most enticing, and is the option I have the most questions about. I know putting a motor on a lathe head and setting the RPM with a separate control would work, but I would want the spindle to be as integrated as possible.
The main questions I'm thinking about are:
Can I create a new, or piggy-back off the signal being sent to the main spindle VFD to control a second spindle speed from the controller?

I know rigid tapping was an option for my machine (which it isn't equipped with) Can i purchase an encoder and attach it to a second spindle?
The main things I would be interested in doing with an encoder attached would be threading, and the positioning of the spindle if possible.
On the partner I machines equipped with rigid tapping does anyone know if you can actually index the spindle to a specific location? Like an M19 Sxxxx and have the spindle index to 45°?

If those things were possible, I think I could dream up and fabricate a pneumatic brake as well to be controlled with a extra M code. So, in my most ideal of extenuating circumstances I could be able to control the lathe spindle with a M3/M4 Sxxxx and also use it as an indexer with a M19 Sxxxx, and even have a brake I could engage with an M code so I could machine while indexed to a specific angle.

Pros:
Cheaper than my 3rd option
Probably the most fun of the 3 options
Longer bar stock could be used and pulled to length
Possibility for CNC controlled speed
Possibility for 4th axis positioning
would allow me to use the main spindle as live x axis tooling

Cons:
More expensive than my 1st option
Would required the most time in design/building/electrical to even hope to have the functionality i want.
half the things I want to do with this option may not be possible.



Option 3. - Add a 4th axis to the machine.
I have been shopping around for an extra motion controller, servo, and servo amp. I'm pretty sure this would be the most expensive option, but it would have the obvious benefit of adding 4th axis positioning and machining capability to the machine. The main thing I don't know is, can you use the A axis as a turning spindle? I know the max RPM would have other factors like what motor, lathe head, gearing, etc. But my main question is, would the centurion 5 controller if equipped with a 4th axis, be able to control the A axis with a direction and RPM like a turning spindle?

Pros:
4th axis
Second most fun option

Cons:
Most expensive
Might not actually be able to turn



Has anyone done any of the above things before? Or can anyone think about any other fun or cool possibility's there might be? Also, does anyone know of any type of Mcode or similar you might be able to set to make the machine read diametrically in the X axis? I'm not too concerned about programming because I think i could modify a MasterCam or PartMaker post to work for me. Just curious if there are any other options. Possibly dual booting Mill/Turning software versions?


Thanks for your thoughts and time!!
-Sly2