Schaublin 125-CNC retrofit.

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01 Mar 2021 08:54 #200515 by RotarySMP
I still need to pull one and measure it. Unfortunately there is no documentation on the electrical characteristics.
Mark

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01 Mar 2021 09:36 - 01 Mar 2021 09:53 #200526 by anfänger
if you are lucky it‘s on the servos them self. And your machine is so clean that you can read it. On my machine I had some places where I couldn’t read anything before cleaning and I clean the letters off together with the grime :D
Last edit: 01 Mar 2021 09:53 by anfänger.

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01 Mar 2021 09:41 #200528 by RotarySMP
Good point. Those huge cast aluminum motor housings might have a data plate underneath. I didn't think to look. Or those are just huge motor covers, and the motors are inside :) Overkill was a thing with this lathe.
Mark.

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01 Mar 2021 12:01 #200683 by db1981
Replied by db1981 on topic Schaublin 125-CNC retrofit.
@Anfänger

if you need some information, just ask ... my wife got all type plates re-readable

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01 Mar 2021 12:42 #200687 by anfänger
@db1981 Thanks, but I guess I have figured everything out which stays and the rest I switched to something new, where I know the parameters. But do you have a thread or pictures somewhere? I would love to see your machine.

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01 Mar 2021 14:15 #200693 by RotarySMP
Is there a technical reason to prefer setp/dir vs analog control when driving AC servos?

If I switch to modern AC servos which support either step/dir or +/-10V analog control input, and add linear encoder feed back, I have the choice between the Mesa 7i95 or the 7i97. What are the advantages / disavantages of one over the other?

Actually, if I find AC servo sets which pass their encoder signal back to the controller, I could do closed loop back to LinuxCNC and not have the headache of finding a space to mount a cross slide linear encoder.
Mark

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01 Mar 2021 14:44 - 01 Mar 2021 14:46 #200697 by anfänger
I don’t know, but I prefer +-10V analog control.
The reason is: I have already done it with the Sinumerik
The lichuan servos and drives I use pass an encoder signal to the control and can be driven step/Dir and +-10V Most prefer Step/Dir to avoid tuning, but I found it not to hard (But the drivers were already tuned) I will see later if I regret it. And you can tune without the servos actual attached to the machine.
Last edit: 01 Mar 2021 14:46 by anfänger.
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01 Mar 2021 14:47 #200698 by RotarySMP
I already used analog on the Maho, and had to tune the servos and after a bit of dicking around found a set up which seems fine. I am a big overwhelmed with all the different options right now, but appreciate the inputs.
Mark

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01 Mar 2021 15:00 #200701 by db1981
Replied by db1981 on topic Schaublin 125-CNC retrofit.
common on servo drives is analog control, because you do usually an velocity control. means the position control loop is extern. The drives does only current and velocity loop.

Many drives can do positioning at there own, then step/dir input makes sence. normaly this is not used in cnc control. because in position mode the drive normaly has its own accel and deccel control. This is usefull for stand alone axis oder handling devices.

In the CNC World we need syncronous axis for interpolation use. So if you want to use the drives position loop, something is need like an externclock that all drives are synced and know exactly at which time of the task they have to accept your commanded postion.

I think there exists drives out there which can interpolate the speed command from an step/dir input, but this would not be the common way. For accurancy, precision and fast reaction an well tuned analog input would always be the better choise.

But if you decide to take new AC Servos and drives, i would take a look at an bus controlled drive like Ethercat.... No interface needed, only cat cable between pc and drives, no stres with analog noise or dc offset, no need to wire encoder signals back to the control, no control wires need, no space waste for breakout boards etc...
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01 Mar 2021 15:26 #200703 by RotarySMP
That is an excellent explanation thanks. I watched old Tony's used of Leadshine ELP EC750Z ethercat drivers, and noted that each driver offered a bit of extra I/O.

Is Ethercat fully supported by LinuxCNC? I haven't really followed that. I looked at the wiki and it still mentioned that it is under development. I would still expect to need some Mesa hardware for the user module, MPG's etc.

Mark

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