Help please. Dip switches and mach 3 settings

[Radu_Andrei]

The mains is of 3 wires, live. neutral and earth, the earth going to the utility pole as well.
I did run a separate earth metal rod, because it said in the vfd manual to avoid having the same ground with a welder, and I do weld quite a bit these days.
From what I understand so far, I.ll unite all shieldings from all components in the utility box, and only at that end, and run everything into an earth, be it back in the mains or the metal rod.
If I got it right, I.ll do so in the next days and come back with the results.

Thank you.

[Clive S]

From what I understand so far, I.ll unite all shieldings from all components in the utility box,

By utility box do you mean where your incoming mains is or your control box?

The star point should be in the control box and then connected to your incoming mains earth.

There are plenty of people that use welders without problems ( it is possible that the ground rod is creating a loop)

I use cat5 cable for signals as it has twisted pairs, but you can use any small screened cable

edit: there are other methods to get rid of EMI using ferrite rings on the incoming mains to the VFD

Good look with the mods

[Radu_Andrei]

Sorry, my mistake. I meant the box where all drivers and sources are, I assume control box it.s the name for that.

[Clive S]

Sorry, my mistake. I meant the box where all drivers and sources are, I assume control box it.s the name for that.

Yes.

[Radu_Andrei]

Hi Clive,
I did what you said with the shieldings and it works. Almost perfect. The only thing left, is that my pc behaves a bit weird sometimes, for a few seconds, when I turn off the vfd, weird meaning the cursor is dancing on my screen for apx 10-15 sec and them returns to normal.
I'll try to use a ferrite ring as you mentioned, for the vfd mains, as that cable is not shielded.
The motors are working fine so far.
So THANK YOU!

I.ll keep in mind your suggestion about a double ballscrew drive and one motor, if any issues will come up with this design. This change on it.s own takes a long time, as I.ll need to build and buy a quite a few extra parts to make it work, so maybe wishful thinking might work this time and function ok as it is.
Even if I have the hardware to add two motors, I.ll avoid this method, as in this last problem I had with noise, the motors were spinning in random ways, not to mention other possible hardware failures which might get them out of sync, and it looks problematic to a point of damaging some expensive parts.
A 5 feet belt might cause some trouble as well, but with enough patience I think I can make it work.
So once again thank you.


As for the second issue, with the limit switches, any idea what I.m doing wrong?
All 6 limits are wired in pairs of two, in series like in the photo, NC, where one wire goes into a numbered pin, and the other into the ground pin. P10 to 12 being used in this case for limits. How should I set this in mach3?

I.m new to this forum and not sure what.s the proper way to post questions. Should I separate the questions and post them in certain categories or ask all the quesions in one thread?

[Clive S]

Ok I would keep all the questions in one thread as it helps to see the history.

Re the twin screws I use two motors with out issue. I think it is about half and half ie some use two and others one motor. There are pro's and con's for both.

Do you have homing switches ? generally on the Z axis it only needs a switch at the top. I would set that up as a combined home and limit switch .

You can wire all the limits in series to one pin. ( set that up in ports and pins in Mach) and also set up soft limits as the machine when homed should never hit a limit.

There are plenty of vids on the net:- https://www.youtube.com/watch?v=ma7lMocQbv0 if that helps

[cropwell]

As for the second issue, with the limit switches, any idea what I.m doing wrong?
All 6 limits are wired in pairs of two, in series like in the photo, NC, where one wire goes into a numbered pin, and the other into the ground pin. P10 to 12 being used in this case for limits. How should I set this in mach3?

In Mach3, Go into Config, - Ports and Pins, - Input Signals, - Automated Setup of Inputs and follow the instructions.

If you don't get a response from the change of state of the switch, then you have a wiring problem. If you get a response it sets the input for you.

[Radu_Andrei]

Hi again.

I wired the switches and e stop did the setup as cropwell said. All fine until I power up the steppers, and then I get noise problems again, limit switches triggered, external estop requested message which sometime does not reset.
I disconnected the vfd and still no good.

As adviced by Clive S, I did more research on this topic, and ironically, that raised more questions.
1. is it a bad grounding practice to pigtail for example the stepper shieldings, and then run a ground wire to the mains earth, or should I run a separate ground wire from each shield to the earth. Does it make a difference?
2. as the spindle is set on conductive material, it.s ground wire becomes the framework.s ground as well, and running another ground for the frame will only create a ground loop. is that correct?
3. does the fact that having all components in one enclosure, raise this kind of problems, even if all wiring and grounding is done correct? should I have 3 separate ones, pc, stepper control, and vfd?
4. all wires run in the cable drag chain, meaning I have low and high voltage right next to each other. so from all I found online, the easiest way in my opinion is to add a relay next to the breakout board, and have the limit switch wires at 12 or 24 v. or should i physically separate them a couple inches apart, or improvise a separate carrier for the low voltage wires?
5. for estops and limits, I have an "hardware" and a "software" estop, one to a contactor, one to mach3, is it useful or necessary to approach the limit switches in a mechanical way? (like some relay which kills the power to the driver, or source)
6. in the vfd manual it says that you should not use a contactor as a switch for the vfd. So i use a cam switch to turn it on, but wired after the contactor, so hitting the "hardware" estop, will kill power to everything, turning just in this cases the contactor into a switch. The I reset the cam switch to zero, power up the contactor again, and turn on and off the vfd from this cam switch. Is there any problem in this wiring method?
7. except the vfd main, where else should ferrite accessories be used? sources mains, between sourced and drivers, breakout board 5v wires.
8. does the breakout board, being close to the drivers and/or vfd, can cause noise issues?


I.m considering taking all the electronics apart and start from scratch, a better cleaner design, easier to troubleshoot, and would appreciate very much an advice on how you would do it. Assuming you have in front of you all the parts involved, how would you design it, in order to never, or at least most of the time, not encounter this kind of problems.

[cropwell]

Hi,

Having typed a long and laborious answer to some of your points, I then lost it all because this forum software is crap.

Here we go again :-----

1. a: Pigtailing - no problem, just remember shields should only be earthed at one end or you may get earth currents to make your shield as the primary in a transformer with the secondaries as your signal wires.

1. b: Single earth point in control box, all earths and shields and mains earth to it. Topographically, earth connections are a star, however spur connection is allowed as long as it is a single line spur chain earthed at one end only at the star point.



2. Yes.

3. The VFD is usually the main culprit in creating electrical noise and it is common practice to keep it out of the main enclosure (which should be an earthed, shielded box I.E. not plastic).

4. DC voltage supply lines are normally no problem in a steady state, switching transients can be a nuisance, but these would only be when there is an inductive load, like a pump motor, so these are best shielded. Homes and limit switches are normally in a steady state, but it wouldn't hurt to shield them against stray EM crap.

5 and 6 - whatever !

7. I hate ferrites and their nasty little cousins - slugs. Design out the problem if you can.

8. Noise from the BoB, not usually (only when it gets drunk on a Saturday night) but seriously - I refer you back to 3 above.

You should test each earth connection by continuity checking from the central earth point to the earthed appliance. Disconnect the appliance earth and check that the continuity between the earth point and the appliance then disappears. If it doesn't - you had a loop.

Hope this helps !

[Clive S]

As Rob said. But I hate timber boxes and think of the fire hazard. If you can go with a metal box with the VFD external to it.

edit: something like this could help https://www.jaycar.com.au/iec-emi-po...6-amp/p/MS4003