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Sounds like it should be a straight forward analog system conversion. What about things like the spindle controls, does it have a tool changer?

Best advice, is first thing e-stop circuits, then get encoder feedback working, then the servo drive enable\disable, then add safeties (limits etc), then confirm directions are correct, finally tune your position loops.

Hi everyone,

I'm currently working on the retrofit of a 3-axis vertical machining center (from 1995) and have decided to use LinuxCNC with Mesa boards. The machine is in excellent mechanical condition, but the original controller (Fagor 8025M) is beginning to fail. I’m still evaluating whether it’s worth repairing, but I’m leaning toward fully modernizing it instead.

Here are the key technical details of the system:

•  **Machine type**: 3-axis vertical milling machine
•  **Original controller**: Fagor 8025M
•  **Motors**: SEM MT30R4-46 brushed DC servos, each with internal tachometers
•  **Drives**: Axor analog drives (Miniclamp 140, Minispeed, Minispeed 140, Minispeed 200) with ±10 V control input
•  **Spindle drive**: Fanuc A06B-6060-H003#H503 (also analog control)
•  **Feedback**:
•  **Main feedback**: KA300 linear scales (Extent 570D), 5 µm resolution, differential outputs (A/B/Z, A-/B-/Z-)
•  **Velocity loop** is handled inside the servo drives via tachometers
•  **Planned control strategy**: Full closed-loop position control via linear scales in LinuxCNC
•  **I/O needs**: At least 18 digital inputs for limits, emergency stop, lubrication pump, coolant, etc.
•  **Desired precision**: Hundredths of a millimeter (0.01 mm) or better
•  **Budget**: About $1500 or less
•  **Planned Mesa boards**: Leaning toward a 5i25 (PCIe) + 7i77 for analog servo control and I/O

The machine will be used for both production and toolmaking, so reliability and precision are key. The current system performs interpolation and achieves 0.01 mm precision, and I’d like to match or improve upon that.

I’d like to ask:

- Has anyone here done a similar retrofit with SEM DC motors and Axor drives?
- Is it reasonable to expect similar or better precision from LinuxCNC using KA300 scales and Mesa hardware?
- Are there any specific concerns when using analog ±10 V control with older servo amplifiers?
- Any advice or experience you could share with full closed-loop systems based on linear feedback?
- I’m also interested in your thoughts on encoder scaling, latency tuning, and best practices for safety inputs and interlocks.

Info:
digital-readout.com/wp-content/uploads/2...stallation-guide.pdf
www.axorindustries.com/wp-content/upload...ce-Manual-MS-Eng.pdf
www.mroelectric.com/static/app/product/p...a06b-6044-manual.pdf
forum.linuxcnc.org/media/kunena/attachme...17/MT30R4Extract.pdf

Thanks in advance for any help or tips you can share! I’ve already started digging into the documentation but would really value input from those who’ve done similar projects.

Best regards,  
Santiago
 

Yes, of course. Without permission, Linuxcnc gives an error message.

The distance a 100 ppr encoder moves per step is determined by the scaling in hal. So it can do whatever accuracy you want
There is a good example in the docs
linuxcnc.org/docs/stable/html/examples/mpg.html
Easy to use on Mesa, 
Use a Mux8 instead of mux4 to get up to 8 scaling steps...
 

Does your script have execute permissions?

Some errors here, anything over 4Gb of RAM is wasted on Linuxcnc. (2gb is probably enough if you can buy it today!)
Disk access has no impact on latency.

A more extensive real time latency test suite is included as standard in Debian (and most distros): sudo apt install rt-tests
and nothing in it mentions HDD or SSD
wiki.linuxfoundation.org/realtime/docume...howto/tools/rt-tests

Hello everyone! This is my first post on the forum. I have a problem with setting up custom M codes on Raspberry + 7i95. I need additional outputs to control the equipment. Just turn on and off some outputs on the 7i95.
In principle, nothing complicated, but when executing custom M code, linuxcnc does not display error messages and the pin states on the 7i95 outputs do not change.
There are no changes in halshow either.

I use this image www.linuxcnc.org/iso/rpi-5-debian-bookwo...25-01-27-0140.img.xz

Here is one of the commands (M101)
#!/bin/bash
halcmd setp hm2_7i95.0.ssr.00.out-01 True
exit 0

Even if you intentionally make a mistake in the M command file, linuxcnc still does not give any error messages.
Has anyone encountered this problem on Rasberry Pi?

I have tried it (embedded) in a virtual machine and it seems to work.

Regards
Giovanni

edit... im a nitwhit and was not flashing the firmware into the mesa. it had who knows what firmware from the factory. now im jogging XYZ no worries. trying to add A and B axis.