Ignoramus28478 wrote:
c) The drives seem to have 380v as power in, have control inputs from
the controller setting speed, and what seems to be tachometer
input. (as I said yesterday, the motors definitely have tachometers on
them).


Sounds a little high, 380 V into a rectifier-filter will give ~ 537 V
DC. I suppose if this is a center-tapped
winding, then they could get 270 V, which sounds more reasonable.
d) There is three more wire coming out of the servo drives, that seem
like they would probably be used to drive motors. I am not sure why
three and I am not sure whether I can figure it out reliably (thoigh
maybe I can).

It is very common for the end limit switches to be fed to the servo amp,
to disable the amp to drive toward a tripped limit switch.
This could take 3 wires (common or + 15 V, and the two limit switch
contacts). These would often be set up for an NC switch, so a dirty
contact ot broken wire would disable the amp in a fail-safe manner.
Then, there's the velocity command signal, two wires.
Therefore, I have two choices:

Choice #1: just sell those Bosch drives, which seem like they could
fetch some reasonable amount of $$$ like $300, and follow the original
advice of Karl and install the AMC drives that I purchased on Karl's
recommendation. I will try to test the AMC drives prior to removing
Bosch drives.

Choice #2: Leave Bosch drives plugged in, leave their connection to
servos as is, and hook them up to Jon's PPMC. The attraction of choice
#2 is that it is superficially easier. However, I do not see the
inhibit function on the drives that could be triggered by limit
switches, and thus I think that they are not as safe to use. I would
have to program inhibit functionality in software, which is obviously
less idiot proof than having drives that are unable to overrun the
limit switches. Also, I believe that I may need three phase to run the
mill, which is something that I hope to avoid.

Just make sure you have some system to E-stop the drives. Either
inhibit them or kill the power input with a relay.
The limit switch = inhibit likely runs through some part of the CNC
control, which you have pulled out.

Jon