DIY CNC Mill - Random Limit Switch Errors

I don't see a picture of the actual breakout board, and related wiring. I might be able to pinpoint good locations to add ferrites. Even the parallel cable might benefit, you'd have to use a clip-on split ferrite, but those are more expensive and I have never tried that type. Best put them on the VFD wires first. A customer watched me do that to his project and it made such a difference he asked me if it is black magic.

BOB too close to relay and power wires.

tommylight wrote:

use short cables

 
 

Just noticed this. It is the answer. I think.

Move VFD much closer to motor. Shorter cable from vfd to motor.
That by itself probably fix everything without doing anything else.

Also keep all DC wires far away from AC wires.

In terms of interference, the wires going from vfd to the motor are the baddest. The longer the badder. To a lesser degree all the AC wires are bad when so close to BOB and all. Contactors are also very bad the instant they open/close.

Sorry, I tried uploading pictures of my BOB several times, but it wouldn't do it. I think I got it to work finally.

NWE, even though I have the BOB right next to the contactor and 12v/24v power supplies, I have never had any issues from those. I have consistently been able to run programs without issue with everything except the VFD on. The contactor is part of my Estop circuit, and it only gets turned on before I run a program or off if I hit the Estop. I have only ever experienced issues when the VFD is on.

I experimented yesterday and learned some. I tried connecting it to earth ground, but that did nothing. I tried disconnecting everything from the BOB except for the 24v coming in and the parallel port and USB from the PC (I switched the VFD to manual control). LinuxCNC ran the program with out any trips even though the VFD was running, so the BOB itself can't be the issue. I tried reconnecting one of the stepper driver pulse/direction signal wires (the steppers were completely off) and ran the program again, and it did trip, even though that wire is shielded and grounded.

I will disconnect the second shielding grounding at the motor. I will also try adding ferrites on the VFD wires first. I think we have a couple lying around that we also pulled from other things.

I forgot to mention, VFDs radiate interference out of both incoming and outgoing power wires. Outgoing is by far the worst, but incoming side also quite bad. Thanks for the BOB picture. I circled the power wires going past BOB. Those certainly radiate interference when the VFD is running, everything all the way back to the breaker panel and beyond is affected to a certain extent. I prefer to keep all that AC wiring a minimum of 12" from the BOB.

How long is your parallel port cable? Is it shielded? The longer it is, the more interference it can collect. If it is shielded then I would think no worry.