fanuc motor questions

Yannis wrote: i understand that i have to compromised
The question is from the data of the 8i20 and label of the motor can we calculate (estimate) what to expect (more or less) will the motor run to what percentage of his capabilities
Also how long do you use the drivers(amplifiers) are they reliable?
and what else i have to replace in the machine to convert it?

No, I don't think that we can even speculate without knowing the current limits set in the existing drives. Maybe they are not configured to push 40A through the 15A motors, or maybe they are.

andypugh wrote No, I don't think that we can even speculate without knowing the current limits set in the existing drives
is this (current limit setting) some software setting of the driver or is it something switch?

Yannis wrote: andypugh wrote No, I don't think that we can even speculate without knowing the current limits set in the existing drives
is this (current limit setting) some software setting of the driver or is it something switch?

I would expect it to be a software setting, but it could be set by a DIP switch.

ok
time for calculation
if i want to make the motors run with 8i20 what else do i need
will i use the existing encoder of the motors?
i believe i will need power suplly
anything else ?

You can probably use the existing power supply.

You would need an FPGA card and adaptor (either 7i44 or 7i74 depending on the FPGA card chosen).

And a firmware that puts 4 x smart serial and 4 x Fanuc encoder on the 7ix4 card.

At your opinion what is the best combination for this?
FPGA, 7IX4 ,And a firmware that puts 4 x smart serial and 4 x Fanuc encoder on the 7ix4 card.
For the c axis motor sud i use 8i20 or there is a smaller driver to combined with the small fanuc motor (<750watt)

Yannis wrote: At your opinion what is the best combination for this?
FPGA, 7IX4 ,And a firmware that puts 4 x smart serial and 4 x Fanuc encoder on the 7ix4 card.
For the c axis motor sud i use 8i20 or there is a smaller driver to combined with the small fanuc motor (<750watt)

For my lathe I decided that the 5i24, 7i44, 7i84 and 8i20 combination was best for me. But your choice might be different.

8i20 is fine for a 750W motor The smaller Mesa (and Pico) drives are rated <400W I think (and not 200V)

But first I would check that you can read the encoder data using the Mesa firmware. Which is why I suggested hooking one up to your existing mesa cards as an experiment.

andypugh wrote Which is why I suggested hooking one up to your existing mesa cards as an experiment.
sorry andypugh now i understand your suggestion

first of all i wold check the price of the combination
i all ready ask for quotation for 3 Chinese servomotor 2.3 kw 1500 rpm 15 Nm
and one 400 watt for the c axis
(i already use this motor in a homemade router with mach3 for 3,5 years with no worries)

Can i use this driver with the proper encoder to control the fanuc motors?
www.aliexpress.com/item/AC-Servo-Drive-G...4bed945102dffbc0a642

Do you have some evidence that it has the required power capability? I can't see any (explicit) current or torque specs on that page.

It appears to support only step/dir (and variants) control so LinuxCNC would be operating open-loop (not that that is necessarily a problem)