Best Drive for Fanuc AC servos

Ive just bought a Boxford 250F that is running 3ph Fanuc OT system. I had planned to runn it off a converter but I understand that the OT system is quite old and cant handle large programmes.

I could reto fit with steppers but it seems crazy to loss the fanuc servos for steppers.

If I convert to 240v single phase I would like to retain the motors and run from linux cnc with mesa cards.

Ive seen The pico system and granite devices do a compatable drives but the pico is standalone and the GD is pricey.

Are there any other drives available or anyone done a similar project?

If the existing servo drives work (technically they're Servo Amplifiers, and a search should turn up more options) , keep them. You'll just need to figure out what they are, and what signals they need to run (they'll be +/-10V analogue drives, but you'll need to find enable/fault signals).

Other option is you convert to something like the CNC Drive DC servo drives, which will accept a step/dir signal, removing the need for an analogue controller.

Unfortunally the lathe is at a freinds workshop at the moment so I cant check model numbers ect. I just assumed that the Fanuc drives cant be used as I couldnt find any examlples of people doing it. Also they are 3 phase so I would still need a rotary converter.

in the documents it looks like the spindle VFD has already been changed for a Mitubishi 240v one, if so that takes care of the spindle so its only the servo drives that need to be changed to get it all on 240v.

Can I use DC servo drives on an AC motor?

Are you sure they're AC servos?

From what I'm aware, most machines of that era used DC servos. The 3 phase will go through a transformer, before being rectified to provide DC for the amps.

You really need to get model numbers of everything.

Yes they are definatly red top AC servos and feed 3phase 415v Attachment 23703

I will try and get the numbers tommorow, cheers

Oh.
Selling them and buying some new servos and drives is likely to be the far easier option, if you do want to change the control.

Lack of program memory on a lathe isn't that big a problem, as most lathe programmes aren't that big anyway.
But it all depends on where you want to spend time and money, between running the existing system, or fitting a new system.

I'd be seeing how much a working Fanuc system is worth, and making a decision from there.

The mesa stuff is known to drive motors/servos well.
Granite D. is actually cheap ..

Getting any of the commercial/fanuc servos running well has been an adventure, in general, for others.

It will be very cheap to try with a granite d. system, vs anything else ..
and about 3x easier, imho.

There are endless caveats, most are unlikely.
So it might be it wont work .. but this is 5-10% probability.

Using the granite d. stuff makes you 10x more likely to succeed - imho.

Ross here is the link to the drives https://granitedevices.com/products/

and a page that might be able to walk you through http://www.wiki.eusurplus.com/index.php?title=Main_Page

as you know I am following this:thumsup:

So a big plus for Granite devices then :eagerness:

Not sure I class £420 a drive as cheap though, Would the IONI series be powerfully enough? Modular so I could build up the system as I need it.

Thanks Clive, hadnt found that wiki but looks promising, I could even use my current mesa cards as the GD's accept step direction signals as well as 0-10v

Had a look today and the motors are Type 3-OS, A06B 0533-B001#7000 and dated 90 04 so guesing April 1990

6 pole, 112v, 0.5Nm and 1 amp, google seems to indicate a 2000ppr incremental encoder.

Are they worth saving or just replace with a all new drives.