(NEWBIE) How to use an (Fanuc) AC Spindle servo motor for an DIY CNC router

Sorry for my late reply!

Again, a BIG THANKS to you Andy for answering again all my questions ! Without your help i wouldnt make an step for the next week for sure

Also thank you for telling me about the 7i73 card, because i wouldnt know that and would have to order it again and wait Have added it to my list and will order this cards: 7I77, 6I25, 7i73

I have one more question (again.. ), but that is really not that important, i am just wondering a bit about that:
Why some poeple use Motion controll cards and some not, or do i understand something wrong?
I thought, the motion controll cards are always necessary when using servo motors for the axis. I am also asking because motion boards are on an special category on the Mesa site.

BR,
Denis

First, just for clarity, the Mesa cards used in Linuxcnc are not "motion controllers". They are FPGA cards used for hardware counting and timing. Linuxcnc is the "motion controller".

As to why not every one uses them. Mostly it comes down to cost. And that for a simple stepper config on a simple hobby machine, they just are not usually nessisary.

Where I work we have a few old CNC wood carving machines, that originally, used old DOS PCs to control step motors via parallel ports. I converted these over to Linuxcnc, simply by swapping in a newer PC with Linuxcnc installed. I saw some small performance improvement over the old system (mostly due to better motion control) and I was able to easily add some new features to the machine. But there was no advantage to adding Mesa cards to these since they can't step any faster than they do now with software step generation, so I didn't waste the money on unnecessary hardware.

The reason cards like Mesa's are needed for a servo, is mostly because of the very fast encoder counts generated by the high resolution incremental encoders needed for good servo control. It is technically possible to read an encoder and generate a pwm to create an analog signal to control a servo using software through the parallel port, but the possible performance and resolutions will not be very good, compared to what can be done in hardware.

Thanks for your answer Todd, but i want to be honest, i am a bit wierd now.

First, just for clarity, the Mesa cards used in Linuxcnc are not "motion controllers". They are FPGA cards used for hardware counting and timing. Linuxcnc is the "motion controller".

As to why not every one uses them. Mostly it comes down to cost. And that for a simple stepper config on a simple hobby machine, they just are not usually nessisary.

For me everything is conflicting a bit.. Also, because on the Mesa store site is an Category named "LinuxCNC supported boards" and there is an Sub-Category named "Motion Control Cards", but there are other cards listed then the cards i should use for servo motors and drives: 7I77-6I25 + 7i73. So, i am asking whats the difference between "Motion control boards

You are saying "As to why not every one uses them", do you mean the Mesa cards i want to use or "motion control cards" ?

I changed my mind about using an used Fanuc spindle motor with an VFD, instead i want to use an "Servo Spindle Motor + Drive" from Aliexpress, so i have 2 very very important questions (im pretty sure that are the last questions!):

1. Would that "Servo Spindle Motor + Drive" (Analog +-10V) work with: Mesa 7I77-6I25 + 7i73 and LinuxCNC:
Spindle Servo Driver and motor 3.7kw,3ph, 380V

2. Would this Servos for my XYZ Axis work: AC 1KW 80mm 4N.M 2500RPM CNC Servo Motor 80ST-M04025+Matched Servo Driver+3m Cables 220V Servo System Kit from Factory Direct
Just a bit wierd informations for me, because on top of the description reads ...modbus "R232/R485", then next information is "Servo Drive Features: With MODBUS communication performance(RS-485 / RS-422 / RS-232), ASCII and RTU communication protocol" and in the Wiring Diagram reads: RS-232/48 communication port connect wird PC"
Then on the "7i77 - card" reads this in the description: "One RS-422 interface is provided for I/O expansion via a serial I/O daughtercard. All field wiring is terminated in pluggable 3.5 mm screw terminal blocks."
Do i understand it correctly: The Servo-Drive does support RS-232 / RS-485 / RS-422 that wire i need to connect to my PC ? I mean i will have 3 Servos Drives, that means 3 Wires + Spindle Servo Drive ?!
Too much for me...

Guys, im sorry for asking you all that questions.
Currently i feel a bit stupid, but i have to say, its the first time ever i have such problems (really). I never had to use so much time to search informations, ask poeple in forums, etc. .
I have always build my computers by own self (i know its something different) and everything had make some sense for me very quickly, but now its really to much for me.
Respect for your Knowledge and i am a bit wondering how long i took you guys to get that knowledge. Just cant believe someone without any experience with CNC would know all that stuff. Too many variaties of setups and components..
For me its also always pretty important to understand those things, and not just get told what i have to do and what components i need, for example in this case with the CNC equipment, but i think i will not understand it until i build couple different setups.

BR,
Denis

1 Yes
2 Maybe, You would need to get a manual for the drives to be sure. (I could not easily find one on line). If the the drives are capable of being controlled with a +/-10V velocity(speed) command, then yes they will work well with a 7i77 card. They probably do, but I could not find any definitive answer.

The RS422 interface is probably not a viable option for an axis control in Linuxcnc.

I had once looked into similar servos from China, but never went through with the purchase. So I can't really comment on them.

Thanks for your reply!

Okay, then i am again at an point where i dont know what to do/what i need.
If the RS422 interface is not viable, which would be then viable ?
I have found that manual: dl.dropboxusercontent.com/u/19663270/Lic...struction%20Book.pdf
Couldnt find anything about "velocity" and also not +/-10V velocity(speed) command, but "Analog quantity
input port: Analog quantity input signal, input range 0～10V.
I found other servo motors which has this info: 0 ~ ±10 VDC, but that should be the same like 0～10V.

Lets maybe forget that with the "real servo motors and drives".
The cheaper option and maybe less complicated will be the Easy Servo Stepper motors and Drives which uses Step/Dir.
I have read quiet good opinions about the Easy servo system and was looking for the boards/cards i should use for them.
So, i have found here in this forum an Thread Easy Servo with Pico universal stepper controller ( where the user "Andypugh" wrote to use the Pico universal stepper controller with the "Parallel port card". In my case, if i want to use the Servo Spindle motor, i would also need the "Spindle DAC card". Is it right and are that all cards i need?

An question to the Easy Servo system wiring. Here an picture: Easy Servo Wiring :
The R232 wire (would need usb adapter) is just for configuration through Easy Drive software and has to be used only ones, correct?

What do you think, is it an good alternative to the real servo motors?

Thanks in advance!

BR,
Denis

Thanks andy for your quick reply!

Those are actually all motor drives (stepper motor and servo motor). They are the layer between the interface card and the motors themselves.

Okay, was just wondering why they are named Motion control and the other different.

Page 12 shows +/- 10V on terminals 18 and 19. That would work with a 7i77.

Which Page do you mean, because the link is for the Aliexpress product page.

I have been learning about CNC for about 7 tears, since I first installed LinuxCNC. I have actually learned most of what I know from _answering_ questions on here.

Wow, okay thats a long time! Good that this forum has some experienced poeple who also help

That should work. As will the Mesa 7i76 / 6i25 plug-and-go-kit.
(You can even use a 7i76 and a 7i77 on one 6i25 at the same time.)

PERFECT Will add that to my list and later choose. Just dont know which is "better", but i am pretty sure they both have some advantages and disadvantages.

Would you recommend to go with Easy servo system ? When i read the differences between closed loop steppers like Easy servo and real servo motors, then i think the only big difference is the constant torque on the servo motors.

Also i just dont know how much Nm i would need. I have tryed some calculators, but i dont trust them.
What i can say now is that the Gantry will be quiet heavy, for sure about 300kg. At least i should go for that weight when not even more. I want an very universal machine, mostly for steel and aluminium, but would also like to cut sheet metal plates and maybe MDF which are mostly available in 2500mm x 1250mm, so the table should be about 2600mm x 1350mm. I first thought to build an Fixed gantry, but then i would need an second router for sheet metal and mdf (plasma + high speed mill), because i dont want to use +5000mm for the Y-axis .
Would be 10Nm enough or is it way to less ?

That question can maybe not been answered, what is totally fine for me. I will more likely go for oversized servo steppers then to to weak ones.

You guys helped me already alot, thanks!

BR,
Denis

Further info. Looking more carefully at the Lichuan manual, of you look on page 16, second picture, and copy the text hiding under the picture to paste somewhere else, it says "-10V~10V"

Also, the Chinese translates to "Servo driver"
translate.google.com/#zh-CN/en/伺服驱动器
(Might be useful in other places)

You are right, have found that. But the reason i thought to go for the Easy servo is also because i found some thread here in forum where someone had exactly that problem with the 0-10V / -10 ~ 10V.. Somehow i cant find that in my history any more, but he couldnt give them any more back and he wasnt very happy with that purchase. Have a bit fear that i will have some big problems later...