Earthing?

Thank you, Neil, I'm with you. Though in my head I am initially thinking that it may not be so easy to implement on a vertical mill, say, the X axis, sensor somewhere in the middle, hitting targets at either extreme...
I can see the opposite working, i.e. sensor stationary in the middle and triggers at the extreme ends moving.

Edward

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Originally Posted by Edward

I can see the opposite working, i.e. sensor stationary in the middle and triggers at the extreme ends moving.

Edward

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Neil answered for me but no difference if sensor moves or Target moves. Infact it's common on mills for the Switch to be stationery and the targets or Ramps if mechaincal type Switch to move with table or saddle. See pic.
Attachment 20385

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Originally Posted by Robin Hewitt

Edward
You do whatever seems best to you, you cannot actually go far wrong. Don't worry about me an Jazz, I like winding him up and he likes screaming obscenities at his computer, it's a match made in heaven, no lasting damage has been done.

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Robin you don't whind me up and believe it or not don't curse you to the PC, like you it wouldn't listen.! . . . You do Piss me off with the one line sarcastic unhelpful replys and excrament which comes from your fingers.

However much as I'd like to go at it with you decided In the interest of not hi-jacking (more) Edwards thread and fact can't be arsed after long day I'm not going to endulge your delusion of whinding me up by replying to your challenge regards Screening and Metal enclosures.

Anyone who want's to follow your Stupid approach is very welcome to go for it.!! . . . . They will soon see who was correct.

Thank you, Dean. The picture says it all. Not only do you save on wiring, but you save on sensors too! I think I will implement something like this.

Edward

A couple of questions regarding earthing in a control box
I'm going to run the screened 4 core wire from steppers to sockets on the metal case and run the screened wire from the inside of the the case (soldered pins on the stepper connector insulated with heat shrink) is it sensible to cover the inside of the socket with copper tape as a screen and to continue the screen continuity? Would I be right in thinking that as the case is earthed I won't need an extra wire from the connector to the bus bar ? I'm going to use a bus bar to connect the earth wires (star earthing) should I bolt the bus bar to the case or insulate it? The switching power supply has a metal case I assume as it will be bolted to the case it doesn't need an extra earth wire. I assume all metal cased items such as stepper drivers are earthed by the mounting bolts, or is it better to insulate them and run extra earths to the bus bar. One last thing is that the boxes holding the connections from the steppers are plastic. Is it worth screening the inside of the boxes but having no electrical contact to the machine frame so that the earthing is only connected at the busbar. I hope this makes sense.

Cheers

Andrew

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Originally Posted by the great waldo

A couple of questions regarding earthing in a control box
I'm going to run the screened 4 core wire from steppers to sockets on the metal case and run the screened wire from the inside of the the case (soldered pins on the stepper connector insulated with heat shrink) is it sensible to cover the inside of the socket with copper tape as a screen and to continue the screen continuity?

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It's not that critical really but won't hurt if you want to go to that much trouble.

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Originally Posted by the great waldo

Would I be right in thinking that as the case is earthed I won't need an extra wire from the connector to the bus bar ? I'm going to use a bus bar to connect the earth wires (star earthing) should I bolt the bus bar to the case or insulate it?

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Bolt the Bus bar to Cabinet and run all screen wires back to this. Because case is Earth via bus bar then won't need wire from connector body if that's what you mean.

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Originally Posted by the great waldo

The switching power supply has a metal case I assume as it will be bolted to the case it doesn't need an extra earth wire. I assume all metal cased items such as stepper drivers are earthed by the mounting bolts, or is it better to insulate them and run extra earths to the bus bar.

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Just bolt them down to the case.

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Originally Posted by the great waldo

One last thing is that the boxes holding the connections from the steppers are plastic. Is it worth screening the inside of the boxes but having no electrical contact to the machine frame so that the earthing is only connected at the busbar. I hope this makes sense.

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No they will be fine. Don't over complicate things because you can easily introduce problems in your attempts to avoid issues. All you need to do is run all Screens and Earth's back to Star point. If you introduce extra Earth wires etc you can easily create ground loops.

Mains things are.
Shields & earths back to Star point.
Stepper sheilds Earthed at star point only not motor end.
Run all signals wires far away from Mains voltage wires as possible.

Thanks Jazz
As the screen for the steppers is connected at the socket via the chassis should I leave both ends of the screen unconnected or is it better to run the driver end of the screen to the bus bar?
Thanks again
Andrew

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Originally Posted by the great waldo

Thanks Jazz
As the screen for the steppers is connected at the socket via the chassis should I leave both ends of the screen unconnected or is it better to run the driver end of the screen to the bus bar?
Thanks again
Andrew

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Others might have a different view but I have done it like you and grounded the screens at the sockets and the plugs. But then I connected a ground wire bolted to the panel close to the sockets and ran that to the star point.

Then you don't ground the other ends of the cable ie at the driver or motors

Thanks Clive.
Just for other forumites make sure there is continuity on the chassis holes for the sockets. On my box only one socket made a connection, all the others were insulated by the case coating/finish. This needs to be corrected.
Cheers.
Andrew

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Originally Posted by the great waldo

Thanks Clive.
Just for other forumites make sure there is continuity on the chassis holes for the sockets. On my box only one socket made a connection, all the others were insulated by the case coating/finish. This needs to be corrected.
Cheers.
Andrew

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I'm also using an epoxy finish steel cabinet, and don't trust any mounting bolts to earth to the cabinet. I've used ground wires from sockets back to the star point, which is a stud welded to the inside of the cabinet.

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Originally Posted by Neale

I'm also using an epoxy finish steel cabinet, and don't trust any mounting bolts to earth to the cabinet. I've used ground wires from sockets back to the star point, which is a stud welded to the inside of the cabinet.

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Yes I should have said that as I have also done the same thing with the mains earth to the star point.