Noob looking for little advice...

[magicniner]

(which I always thought was the C??).

There are VMC, HMC and Lathe Conventions, Mill/Turn adds complexity and a degree of the manufacturer making it up as they go along.
On a lathe the main spindle is on the Z Axis.

[magicniner]

A conventional lathe has no Y axis ;-)

[m_c]

Lathe axis are confusing.

As magicniner says, inline with the spindle is the Z axis.
Standard across the spindle line is the X.
Y axis is typically if the entire X/Z axis can be moved (typically it won't be at 90 deg to the X)
C is typically if the spindle can be positional controlled.

Off course, by the time you get into that level of complexity, you're verging on mill turn, in which case it really does vary.
I just tried searching for a suitable diagram, and have just learnt nobody really uses an A-axis on lathe (should be rotary around the X axis), and B-axis which should be rotary around the Y axis, is more likely to be used for the tailstock/second spindle housing linear Z movement.

However I'm sure I've seen diagrams where the tool holders are mounted on rotational axis labelled A and B.

[magicniner]

Back to the main question though -
If you want continuous rotational positional control of your lathe spindle then you will need a sensor on the spindle and a motor/controller capable of the speed for conventional turning and also the hold for stationary and torque for slow mill-turn operations with live tooling, (that eliminates steppers) a controller capable of operating a brake on the spindle may be required.
Given the power in a motor required for slow moves and stationary hold for live tooling, even with a brake you will need a higher power servo motor than you think (multiple rather than fractional horse), I think your proposed budget may require expansion, you'll only really find out when you start asking for quotes.
Before you buy anything you should start with your chosen CAM software and proposed controller as this will have to deal with running the hardware and if your project ends up needing a 4/5 axis CAM and a genuine Fanuc controller you may find your budget not going far.

[MRob]

The circuit board side is my biggest worry... I'll focus on researching that for now then, really I am so clueless in that area it's embaressing. Hopefully I'll find some sort of bodge workaround instead of paying an arm and a leg. I mean I could pay more, but I kinda dont want to!

Interesting with the power of the servo - looking on alibaba at similar 4 axis lathes with live tooling, they seem to be good with 3kW, which is reassuring.

Re axis - OK I am using X, Z, C and maybe B. Got it!

[m_c]

Dynomotion KFlop could handle what you're trying to do, provided you understand the kinematics involved, and aren't averse to a bit C programming.

Mach could be used, but I think that would involve CAM being responsible for handling tool offsets/angles, as I don't think it can handle the tool offsests when you get into angling tools around.

I'm sure LinuxCNC might be able to handle it, but I've got no idea how much it can do without getting deep into custom programming.

[magicniner]

Mach could be used, but I think that would involve CAM being responsible for handling tool offsets/angles, as I don't think it can handle the tool offsests when you get into angling tools around.

Once you move into 3D parts with 4 axes and above it's best to have your CAM handle all that, that way provided your machine model is accurate your simulation will be accurate, as will any machined parts saved out of your simulation as solids.

[cropwell]

A conventional lathe has no Y axis ;-)

Which confuses me as my digital readout on the lathe is X and Y. There again, the lathe functions perfectly well without a Z axis (do I hear a violin plaintively playing 'Hearts and Flowers'?)

[magicniner]

Which confuses me as my digital readout on the lathe is X and Y. There again, the lathe functions perfectly well without a Z axis (do I hear a violin plaintively playing 'Hearts and Flowers'?)

That just means it's a generic 2 Axis readout that is not specifically made for a lathe and is thus incorrectly labelled for lathe use.
If it were a Lathe Specific model it would have lathe specific functions including Diameter and Radius display of X and a table of offsets for tools/holders, like this one-



That's my 0.75Kw, 20 year old Siemens Micromaster Vector on the left BTW ;-)

[cropwell]

That just means it's a generic 2 Axis readout

Yes I know, really it doesn't matter what letters you label an axis with, you could also call them Red, Green and Blue. I was just in a frivolous mood. I have the SINO SDS6 2V readout, it just seems to have more functions I have no clue how to use :(....... [sad old bugger dribbling].

Rob