Regarding the AB drives, not sure if I made it clear when I said disabling the sercos turned them into Indexing drives. What I maybe should have said was drives capable of Indexing. You can use them as normal servo drives with either position (step/dir, encoder follower etc) or analogue input. You can also use them as Indexing drives, in fact you can use them as both with an input to change between modes. Example an input could switch between Indexing mode and Position mode (Step/Dir or Follower) or between Position and Analogue or Analogue and Indexing etc.
The advantage I have is I am using these drives for myself so I can afford to use second hand ones and I refuse to pay too much for them, that may change is I was really desperate for one but at the moment I have quite a few spares and the most I have paid was under £300 for the 22Kw ones. There are lots of the smaller drives (3Kw and under) for £300 or so but being a poor boy (as I was informed in another thread
) I wont buy at that price.
Your problem with this approach is you are putting a product to market so even though picking up a cheap one for your proto may be an option, you would have to consider the new cost for your product.
Regarding speed, I dont have any commercial changers with the exception of the Chirons and it is air cylinders. They are adjustable like any air system is and have actually been reduced from default. Tool change is supposed to be 0.9 seconds tool to tool but with the Up/Down cage being slowed it is approx 1.8seconds.
The lathe did have a turret on it when I got it but it was hydraulic and worked by rack so really just one speed unless you adjusted the flow rate. The turret I made to replace that has the servo and I have limited the rotation to what I think is suitable and wont put too much stress on things, I could have turned the speed up to probably 5 or more times what I have. Heres a vid showing the speed I settled on.
http://www.youtube.com/watch?v=hRTfxuXf6yk Hood