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Help to get my CNC router working again please!


My CNC router ran successfully for five years (not heavy use) but has been failing since Sep-21 (just over 12 months at time of writing) and I have not been successful in identifying the problem(s).  The machine has been stopping with “Servo drive disabled” messages, sometimes in the middle of a job and sometimes when powered up but inactive!

The router is a substantially built, 3-axis, 5’ x 4’ x 12” movement, workshop-built machine, with 32mm ballscrews and made from 25mm aircraft grade aluminium.  I did not build it, although it was built in my workshop, so I am not as familiar with it as if I had built it; especially the electronics (my background is chemical engineering, computer programming and woodwork, in that order).  The friend who did the electronics is not available.

The control computer is running windows XP and MACH3 and the motion control is by 400w Estun servo drives and motors.  The long axis (X) has master and slave drives while the vertical (Z) and cross gantry (Y) motion have single drives!  I added a second spindle to avoid at least some cutter changes.

I upgraded the primary spindle from a 2.2kW Chinese to a 4kW German one in Dec-19 so I don’t know if the problems are related to this or not.  (The whole machine, apart from the control computer, runs on one 13 amp socket,  so we may be overloading something, but if so it took a long time to manifest).

Individual motors have at times got hotter (70-80 deg C) than they normally run at, although this does not always correlate with working hard or the machine stopping.

When the problem first occurred, it was on the Z servo drive, and I swapped cables so the same drive was controlling a different motor.  The problem stayed with the drive!  I have had drives repaired a few times but have not got to the bottom of why they are failing.

Subsequently, different drives have stopped with MACH3 reporting “Servo drive disabled” and the Estun software, when connected to the offending drive, usually says “A.14 Voltage abnormal” or occasionally “A.04 Overloaded”.

I have had suggestions that 19/20 times, this sort of problem is the motor drawing too much current.  I have tried to buy a current clamp meter from RS Components but they have over 400 different options ranging from £30 to £1,600 and their Live Chat Help was not helpful, except to suggest trying forums.

Q1.  Is buying current meter(s) a sensible way to go, and if so, which of RS’s options do I buy?

Q2. Is there anyone not too far from Wrexham who would be able and willing to help please (paid) as I have not been able to find professional help?


Q3.  The parameters on the different drives seem similar but not identical; I would like to make them all the same!  Is there anyone who could advise please (once the main problem is sorted)