Stepper motor leads

**offlander** · 04-27-2022, 04:00 PM

I recently came into possession of a Messer CNC Plasma table . The machine itself needs some work, but the electrical side of it is definitely non-functional and I believe will need to be replaced. I've retrofit a few milling machines in the past 3 years with Centroid controllers, which some decent results and plan to do the same here now that Centroid has released their own THC.

In the past I used closed-loop, 11.5N-m, steppers motors to drive the mills I've worked on, those motor leads were only 4ft long at a maximum. This Plasma CNC machine has a bed size of 10' x 6' and the whole machine is 17' in length and 9' wide. After measuring some of the existing wire lengths to the Z-axis (to the existing servo motors) they are almost 30 feet in length.

Here's the question; Will a 60V, 11.5 N-m, Stepper motor with encoder feed back function properly on a 30 foot (9 meter) wire lead? If not, what type of drive system would be better suited to it?

Thanks,

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**CNCMAN172** · 04-27-2022, 05:38 PM

Most companies say 30 feet is the max length for cables

**rodw** · 04-30-2022, 02:31 AM

Does it have servos on it now?
If so, I would look at retaining them. Linuxcnc has a few options for older analog 0-10v servos like a Mesa 7i77.
Joey in Ireland is retrofitting a servo driven an Esab 10m x 4m plasma table with linuxcnc with good results.
He's retained the original motors and drives.

To me reverting to steppers is a massive backwards step that substantially devalues the machine...

**offlander** · 05-13-2022, 03:16 PM

As much as I would like to keep the servos, the control cabinet in which the servo drives were housed is decidedly missing what I'm going to assume is very essential hardware (power supplies and hook-ups for the controller). Not to mention I have no instruction manuals for the drives of servos which were manufactured in 1995 according to their nameplates. I understand the argument for wanting servos, they do have attractive points when it comes to torque and precision. But as I already have (4) closed-loop steppers with drives and power supplies, I'll likely stick with what I know. The choice was further made simple when I was able to attach the steppers directly to the 20:1 gear boxes, the bolt pattern and shafts attached directly with no modification.

I'll hold on to the servos, but without power supplies for them, manuals on the drives, the fact they are 27 years old, and the accuracy required for a plasma CNC... Its likely they will not be used.

I do appreciate the input though.
Thanks,