I've been reading around, and I think I've decided on the Sherline 4400 cnc lathe and the Taig 2019 cnc mill.
[Those are both good machines, as long as the parts you're doing fit in their work envelopes]
. As for the drivers/steppers/power supply, I've been looking at the probotix and gecko's, but I'm not sure what I want here.
[The Gecko 540 is pretty hard to beat. They've started selling stepper motors too, which would be a good choice to go with them.]
Is there any downside to getting a stepper which is too powerful?
[Yes, the "holding torque" isn't the only number to pay attention to. Inductance is also important - a motor with too much of it will be sluggish compared to one that may be less powerful in its holding state. ]
I'm wanting a fourth axis for the mill, and quite a few people have used the sherline rotary table. Are there any problems I might encounter here?
[That's what both companies use; it's a solid and well-constructed unit with chucks available.]
Finally, I want to install a power drawbar and might eventually want an atc.
[You won't need the power drawbar for the Taig mill, since it uses an ER taper collet system that tightens with two wrenches. I suppose you could use one on the lathe, but I don't know of any that are available for it. I also haven't seen any Automatic Tool Changers for these machines that I'd recommend, although people seem to enjoy coming up with candidates...]
ComputerSculpture.com — Home Page for Discount Hardware & Software