Machsupport Forum
Mach Discussion => Mach4 General Discussion => Topic started by: JDLopez65 on July 14, 2024, 04:36:38 PM
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So I finally got my X,Y axis movement issues (https://www.machsupport.com/forum/index.php?topic=48870.0) figured out... turns out my X and Y stepper drivers had an incorrect dip switch setting. After correcting this I was able to produce my first ever CNC'd part, although this was not without issue.
Shortly after the start of the second operation I started getting a "Clearing a spurious limit_hit_latch event" error. A quick Google search and I found this thread (http://www.machsupport.com/forum/index.php?topic=37598.0) which was addressing the same issue.
Ok so my spindle motor controller and/or servo motor are causing noise. Apparently a lot of noise and frankly I'm not surprised... I had previous indications that they were noisy. My machine is a DIY CNC conversion I built from a bench top bed mill. When I did the conversion I chose to keep manual milling capabilities AND the already installed DRO. I had seen some erratic behavior on the DROs built in tachometer display during a previous manual milling job.
During the CNC job for this latest part I noticed the machines DRO (not the Mach DROs) was behaving extremely erratic... not only was the tach display all wonky, so were all the axis DRO's.... they were all over the place. This resolved itself what i plugged the machines DRO into a separate outlet. When I did the CNC conversion I added EMI Noise filters on the incoming AC mains for BOTH the spindle motor/controller (240VAC) and the motion control box (120AC).
OK...so apparently the EMI filters alone are not good enough (or perhaps not high quality enough). From the forum thread I found there are suggestions about adding filters to both the input side of the motor controller AND the output side that goes to the servo motor. I have the EMI filer on the input side already, so guess I need to pursue a solution for the output side.
In the previous thread, @Steve Stallings suggested a ferrite ring common mode choke on the outputs of the controller. I know what they are and where to get them... what I don't know is what size ring and how many turns around the core to use.
I would greatly appreciate any suggestions from anyone in the know.
Thanks in advance,
John
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...forgot to mention, the limit switch cabling is shielded...in fact they are purpose built machine limit switches (https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/limit_switches/plunger_actuator/aem2g16z11-3)...not some rinky-dink thing.
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An output side common mode filter (ferrite ring) should be close to the spindle controller (VFD?) and should be large enough to make a loop such that each wire passes thru the ring twice. The ring should be large enough such that all wires are in the same ring. Typically this calls for a ring with 1.5" to 2" outside diameter.
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THANKS Steve...!