Colchester 4000L retrofit

Hello,
I'm investigating a lathe retrofit on a Colchester 4000L Fanuc 0T-A.

I've done a couple of retrofit/hybrid, and 'from scratch' LinuxCNC machines before, but none involving Fanuc, which I know is often difficult-to-impossible depending on the particulars. I've looked at numerous paths forward balancing time/difficulty vs up-front cost. 

Been reading old manuals, searching the forums, and I must admit, taking a significant amount of input from ai, and I have a plan. But, while it was nice to seemingly make rapid progress compared to my previous projects, I would be glad of input from other actual humans. If CNC has taught me anything, it's don't trust a machine! I've tried to include enough relevant detail without turning the post into War and Peace.

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I'll be using MESA boards - most likely a 7i96 connected to a 7i77. I already have them from a previous project where they worked very well.

For axes, I want to keep the Fanuc motors (red caps: A06B-0513-B032#7000 amd A06B-0512), and (for now) their drive/VCU (it's a dual axis unit A16B-1200-0520). 
If I've understood correctly, LinuxCNC can read the positional feedback from the encoders via serial port on the 7i77, then using DC injection to find the magnetic offset, generate commutation data and command the motor via 7i77's 10V into the pre-existing VCU. 

I'll Keep the fanuc spindle motor, an 11kW A06B-0745-B201, which seemingly has an encoder with ABZ output that LinuxCNC can use via encoder input on the 7i77. 

I'm replacing the spindle-driver/VCU (A06B-6060-H008) with a heavy duty VFD. Something like a Yaskawa GA70C2056BBA. The failing fanuc spindle driver is actually the straw that broke the camel's back and instigated this project.

Toolcahanger is a duplomatic BSV-160. There seems to be ample history for successfully using similar units.
Coolant pump is either on or off, I think it'll be OK.

Control will initially be primarily PC based, probably some touch-screen, but will probably add a pendant for easier manual positioning and the dopamine hit of pushing real buttons.

Really just wondering if anything is obviously foolish. 
 

It has a single MPG wheel mounted on the door/control. I might re-use it, but since most of the rest of the existing controls are going away (many worn out keys), I think a detachable pendant with some buttons might be nice for setting up longer work.

More importantly for anyone interested, I think I was wrong on the encoder/commutation stuff. After further investigation, it seems ABZ encoder outputs are available from the VCU and I don't need to worry about commutation, although there is a different wrinkle that's escaping me right now.

A couple of days after I posted about this, I got commandeered to look at a similar vintage milling machine for a repair, or similar refit. A week into that, I had to move on to a more urgent broken production tool. It's been fun. I'll update the thread with my lathe progress, success or failure when I get back to it, but it could be a while.

Having been using chat-bot assistance, I'm mindful that much of it's info on the topic is scraped and recombined from these very forums, so it's important to give back real accurate information about a project's actual viability and methodology when I can.

hey i just saw this and had to comment as i have been down this path about 10 times on big machines.

my experience when i looked into it was that using any of the fanuc stuff was just not worth it compared to new chinese servos. i use the Yuhai brand (have bought like 70 of them now)

a 2.2kw motor and drive 200v input power costs like 300 usd per axis. so 600 usd total. and you get new motors and drives that don't have issues. i tried keeping old electronics going too many times and it didn't work out for me. the i spent like 1000usd trying to fix old fanuc drives and then heidenhain fagor misubishi etc eventually i just come back to what i should have done in the first place and just bought new motors. anyway after 7 years and over 70 motors ranging from 400w up to 4.5kw i have only ever had one motor fail. and no drives and i think that was our fault with bearing misalignment the zaxis brake failed in it. But it is truely nice to just turn the machine on and know that it's just going to work.

also china has very nice vfd drives now you can get a 11kw drive for 200usd. or one that can turn a normal motor(like a pump farm motor even..) into a pretty rigid servo drive for about 900usd for 11kw
anyway let me know if you want any advice cheers