Thanks for all the inputs.  I did quite a bit of research concerning 
the effectiveness vs the amount of work vs the expense of getting the 
machine on line and making chips.
1. Tossing the entire drive train and replacing with a 10 hp 3ph 
motor and vfd to run from 220 single phase...... can't be done... no 
10 hp single phase vfd available at any price.

2. same as above but use 7.5 hp vfd with back gear....  same problem 
as above plus the backgear is PART OF the DC motor and requires 
considerable machining and adapting to take the end bell from the old 
motor and incorporate it into the new drive train.

3. Note that 1 and 2 are what Monarch does now for their "new" and 
rebuilt 10ee's they are NOT for single phase 220 use.

4. Drive the existing system from a single phase in 5 hp vfd...... I 
could not find a 5 hp single phase in vfd and even in the lower hp 
ranges I was looking at $400 and up for which I would be buying all 
kinds of bells and whistles which would be the proverbial mammary 
glands on a male swine since the 3 ph motor must run at 60 hz for the 
rest of the system to work correctly.   Also I would be required to 
bypass any and all means of control from the lathe itself so as not 
to disconnect the vfd load downstream.

5. Replace the 3 ph motor with a 5 hp single phase motor...... 
Probably the neatest solution but the motor and generator are a 
single unit so the single phase motor would have to actually spin 
both the motor and generator IF... there was room enough to mount the 
extra motor and there's not.  I even considered having the 3ph motor 
rewound as single phase but a couple of local motor shops said they 
were not even interested.

6. Toss the MG and install a DC control for the motor..... Most 
integral hp DC controllers are rated 180 volts wide open.... he 10ee 
generator produces from 0 to 300 volts to the motor armature.  It 
would be impossible to recreate that armature voltage from an off the 
shelf controller and problematic to get there with a home built 
one.  The speeds above 1500 rpm are achieved by reducing field 
voltage (120 V DC on the field up to 1500 rpm) so that would not be a 
problem.  300 VDC from 220 VAC is a challenge.


7. Make the existing 3ph motor single phase by installing a static 
phase converter and giving up about 1/3 of the hp......  cheapest solution.

8. Buy a pretty prebuilt Rotary Phase Converter panel for $160 and 
add a locally purchased used 7.5 hp idler for $0 and with a couple of 
hours of running conduit and hanging the panel I'm in business.


Cecil 
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